The end goal of the current buffer overflow detection work[0] is to gain
full compile-time and run-time coverage of all detectable buffer overflows
seen via array indexing or memcpy(), memmove(), and memset(). The str*()
family of functions already have full coverage.
While much of the work for these changes have been on-going for many
releases (i.e. 0-element and 1-element array replacements, as well as
avoiding false positives and fixing discovered overflows[1]), this series
contains the foundational elements of several related buffer overflow
detection improvements by providing new common helpers and FORTIFY_SOURCE
changes needed to gain the introspection required for compiler visibility
into array sizes. Also included are a handful of already Acked instances
using the helpers (or related clean-ups), with many more waiting at the
ready to be taken via subsystem-specific trees[2]. The new helpers are:
- struct_group() for gaining struct member range introspection.
- memset_after() and memset_startat() for clearing to the end of structures.
- DECLARE_FLEX_ARRAY() for using flex arrays in unions or alone in structs.
Also included is the beginning of the refactoring of FORTIFY_SOURCE to
support memcpy() introspection, fix missing and regressed coverage under
GCC, and to prepare to fix the currently broken Clang support. Finishing
this work is part of the larger series[0], but depends on all the false
positives and buffer overflow bug fixes to have landed already and those
that depend on this series to land.
As part of the FORTIFY_SOURCE refactoring, a set of both a compile-time
and run-time tests are added for FORTIFY_SOURCE and the mem*()-family
functions respectively. The compile time tests have found a legitimate
(though corner-case) bug[6] already.
Please note that the appearance of "panic" and "BUG" in the
FORTIFY_SOURCE refactoring are the result of relocating existing code,
and no new use of those code-paths are expected nor desired.
Finally, there are two tree-wide conversions for 0-element arrays and
flexible array unions to gain sane compiler introspection coverage that
result in no known object code differences.
After this series (and the changes that have now landed via netdev
and usb), we are very close to finally being able to build with
-Warray-bounds and -Wzero-length-bounds. However, due corner cases in
GCC[3] and Clang[4], I have not included the last two patches that turn
on these options, as I don't want to introduce any known warnings to
the build. Hopefully these can be solved soon.
[0] https://lore.kernel.org/lkml/20210818060533.3569517-1-keescook@chromium.org/
[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/log/?qt=grep&q=FORTIFY_SOURCE
[2] https://lore.kernel.org/lkml/202108220107.3E26FE6C9C@keescook/
[3] https://lore.kernel.org/lkml/3ab153ec-2798-da4c-f7b1-81b0ac8b0c5b@roeck-us.net/
[4] https://bugs.llvm.org/show_bug.cgi?id=51682
[5] https://lore.kernel.org/lkml/202109051257.29B29745C0@keescook/
[6] https://lore.kernel.org/lkml/20211020200039.170424-1-keescook@chromium.org/
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Merge tag 'overflow-v5.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull overflow updates from Kees Cook:
"The end goal of the current buffer overflow detection work[0] is to
gain full compile-time and run-time coverage of all detectable buffer
overflows seen via array indexing or memcpy(), memmove(), and
memset(). The str*() family of functions already have full coverage.
While much of the work for these changes have been on-going for many
releases (i.e. 0-element and 1-element array replacements, as well as
avoiding false positives and fixing discovered overflows[1]), this
series contains the foundational elements of several related buffer
overflow detection improvements by providing new common helpers and
FORTIFY_SOURCE changes needed to gain the introspection required for
compiler visibility into array sizes. Also included are a handful of
already Acked instances using the helpers (or related clean-ups), with
many more waiting at the ready to be taken via subsystem-specific
trees[2].
The new helpers are:
- struct_group() for gaining struct member range introspection
- memset_after() and memset_startat() for clearing to the end of
structures
- DECLARE_FLEX_ARRAY() for using flex arrays in unions or alone in
structs
Also included is the beginning of the refactoring of FORTIFY_SOURCE to
support memcpy() introspection, fix missing and regressed coverage
under GCC, and to prepare to fix the currently broken Clang support.
Finishing this work is part of the larger series[0], but depends on
all the false positives and buffer overflow bug fixes to have landed
already and those that depend on this series to land.
As part of the FORTIFY_SOURCE refactoring, a set of both a
compile-time and run-time tests are added for FORTIFY_SOURCE and the
mem*()-family functions respectively. The compile time tests have
found a legitimate (though corner-case) bug[6] already.
Please note that the appearance of "panic" and "BUG" in the
FORTIFY_SOURCE refactoring are the result of relocating existing code,
and no new use of those code-paths are expected nor desired.
Finally, there are two tree-wide conversions for 0-element arrays and
flexible array unions to gain sane compiler introspection coverage
that result in no known object code differences.
After this series (and the changes that have now landed via netdev and
usb), we are very close to finally being able to build with
-Warray-bounds and -Wzero-length-bounds.
However, due corner cases in GCC[3] and Clang[4], I have not included
the last two patches that turn on these options, as I don't want to
introduce any known warnings to the build. Hopefully these can be
solved soon"
Link: https://lore.kernel.org/lkml/20210818060533.3569517-1-keescook@chromium.org/ [0]
Link: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/log/?qt=grep&q=FORTIFY_SOURCE [1]
Link: https://lore.kernel.org/lkml/202108220107.3E26FE6C9C@keescook/ [2]
Link: https://lore.kernel.org/lkml/3ab153ec-2798-da4c-f7b1-81b0ac8b0c5b@roeck-us.net/ [3]
Link: https://bugs.llvm.org/show_bug.cgi?id=51682 [4]
Link: https://lore.kernel.org/lkml/202109051257.29B29745C0@keescook/ [5]
Link: https://lore.kernel.org/lkml/20211020200039.170424-1-keescook@chromium.org/ [6]
* tag 'overflow-v5.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: (30 commits)
fortify: strlen: Avoid shadowing previous locals
compiler-gcc.h: Define __SANITIZE_ADDRESS__ under hwaddress sanitizer
treewide: Replace 0-element memcpy() destinations with flexible arrays
treewide: Replace open-coded flex arrays in unions
stddef: Introduce DECLARE_FLEX_ARRAY() helper
btrfs: Use memset_startat() to clear end of struct
string.h: Introduce memset_startat() for wiping trailing members and padding
xfrm: Use memset_after() to clear padding
string.h: Introduce memset_after() for wiping trailing members/padding
lib: Introduce CONFIG_MEMCPY_KUNIT_TEST
fortify: Add compile-time FORTIFY_SOURCE tests
fortify: Allow strlen() and strnlen() to pass compile-time known lengths
fortify: Prepare to improve strnlen() and strlen() warnings
fortify: Fix dropped strcpy() compile-time write overflow check
fortify: Explicitly disable Clang support
fortify: Move remaining fortify helpers into fortify-string.h
lib/string: Move helper functions out of string.c
compiler_types.h: Remove __compiletime_object_size()
cm4000_cs: Use struct_group() to zero struct cm4000_dev region
can: flexcan: Use struct_group() to zero struct flexcan_regs regions
...
Both the decompressor code and the kasan logic try to override
the memcpy() and memmove() definitions, which leading to a clash
in a KASAN-enabled kernel with XZ decompression:
arch/arm/boot/compressed/decompress.c:50:9: error: 'memmove' macro redefined [-Werror,-Wmacro-redefined]
#define memmove memmove
^
arch/arm/include/asm/string.h:59:9: note: previous definition is here
#define memmove(dst, src, len) __memmove(dst, src, len)
^
arch/arm/boot/compressed/decompress.c:51:9: error: 'memcpy' macro redefined [-Werror,-Wmacro-redefined]
#define memcpy memcpy
^
arch/arm/include/asm/string.h:58:9: note: previous definition is here
#define memcpy(dst, src, len) __memcpy(dst, src, len)
^
Here we want the set of functions from the decompressor, so undefine
the other macros before the override.
Link: https://lore.kernel.org/linux-arm-kernel/CACRpkdZYJogU_SN3H9oeVq=zJkRgRT1gDz3xp59gdqWXxw-B=w@mail.gmail.com/
Link: https://lore.kernel.org/lkml/202105091112.F5rmd4By-lkp@intel.com/
Fixes: d6d51a96c7 ("ARM: 9014/2: Replace string mem* functions for KASan")
Fixes: a7f464f3db ("ARM: 7001/2: Wire up support for the XZ decompressor")
Reported-by: kernel test robot <lkp@intel.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Add support for parsing the "linux,usable-memory-range" DT property.
This property is used to describe the usable memory reserved for the
crash dump kernel, and thus makes the memory reservation explicit.
If present, Linux no longer needs to mask the program counter, and rely
on the "mem=" kernel parameter to obtain the start and size of usable
memory.
For backwards compatibility, the traditional method to derive the start
of memory is still used if "linux,usable-memory-range" is absent.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
The core functions of string.c are those that may be implemented by
per-architecture functions, or overloaded by FORTIFY_SOURCE. As a
result, it needs to be built with __NO_FORTIFY. Without this, macros
will collide with function declarations. This was accidentally working
due to -ffreestanding (on some architectures). Make this deterministic
by explicitly setting __NO_FORTIFY and move all the helper functions
into string_helpers.c so that they gain the fortification coverage they
had been missing.
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Andy Lavr <andy.lavr@gmail.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
The merge_fdt_bootargs() function by definition consumes more than 1024
bytes of stack because it has a 1024 byte command line on the stack,
meaning that we always get a warning when building this file:
arch/arm/boot/compressed/atags_to_fdt.c: In function 'merge_fdt_bootargs':
arch/arm/boot/compressed/atags_to_fdt.c:98:1: warning: the frame size of 1032 bytes is larger than 1024 bytes [-Wframe-larger-than=]
However, as this is the decompressor and we know that it has a very shallow
call chain, and we do not actually risk overflowing the kernel stack
at runtime here.
This just shuts up the warning by disabling the warning flag for this
file.
Tested on Nexus 7 2012 builds.
Acked-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: David Heidelberg <david@ixit.cz>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Kbuild cleans up files listed in 'targets'.
'piggy_data' is already added to 'targets' a few lines above.
Adding it to 'clean-files' is redundant.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
- Convert sh and sparc to use generic shell scripts to generate the
syscall headers
- refactor .gitignore files
- Update kernel/config_data.gz only when the content of the .config is
really changed, which avoids the unneeded re-link of vmlinux
- move "remove stale files" workarounds to scripts/remove-stale-files
- suppress unused-but-set-variable warnings by default for Clang as well
- fix locale setting LANG=C to LC_ALL=C
- improve 'make distclean'
- always keep intermediate objects from scripts/link-vmlinux.sh
- move IF_ENABLED out of <linux/kconfig.h> to make it self-contained
- misc cleanups
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Merge tag 'kbuild-v5.13-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Pull more Kbuild updates from Masahiro Yamada:
- Convert sh and sparc to use generic shell scripts to generate the
syscall headers
- refactor .gitignore files
- Update kernel/config_data.gz only when the content of the .config
is really changed, which avoids the unneeded re-link of vmlinux
- move "remove stale files" workarounds to scripts/remove-stale-files
- suppress unused-but-set-variable warnings by default for Clang
as well
- fix locale setting LANG=C to LC_ALL=C
- improve 'make distclean'
- always keep intermediate objects from scripts/link-vmlinux.sh
- move IF_ENABLED out of <linux/kconfig.h> to make it self-contained
- misc cleanups
* tag 'kbuild-v5.13-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (25 commits)
linux/kconfig.h: replace IF_ENABLED() with PTR_IF() in <linux/kernel.h>
kbuild: Don't remove link-vmlinux temporary files on exit/signal
kbuild: remove the unneeded comments for external module builds
kbuild: make distclean remove tag files in sub-directories
kbuild: make distclean work against $(objtree) instead of $(srctree)
kbuild: refactor modname-multi by using suffix-search
kbuild: refactor fdtoverlay rule
kbuild: parameterize the .o part of suffix-search
arch: use cross_compiling to check whether it is a cross build or not
kbuild: remove ARCH=sh64 support from top Makefile
.gitignore: prefix local generated files with a slash
kbuild: replace LANG=C with LC_ALL=C
Makefile: Move -Wno-unused-but-set-variable out of GCC only block
kbuild: add a script to remove stale generated files
kbuild: update config_data.gz only when the content of .config is changed
.gitignore: ignore only top-level modules.builtin
.gitignore: move tags and TAGS close to other tag files
kernel/.gitgnore: remove stale timeconst.h and hz.bc
usr/include: refactor .gitignore
genksyms: fix stale comment
...
We maintain .gitignore and Makefiles so build artifacts are properly
ignored by Git, and cleaned up by 'make clean'. However, the code is
always changing; generated files are often moved to another directory,
or removed when they become unnecessary. Such garbage files tend to be
left over in the source tree because people usually git-pull without
cleaning the tree.
This is not only the noise for 'git status', but also a build issue
in some cases.
One solution is to remove a stale file like commit 223c24a7db ("kbuild:
Automatically remove stale <linux/version.h> file") did. Such workaround
should be removed after a while, but we forget about that if we scatter
the workaround code in random places.
So, this commit adds a new script to collect cleanings of stale files.
As a start point, move the code in arch/arm/boot/compressed/Makefile
into this script.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
The LLVM ld.lld linker uses a different symbol type for __bss_start,
resulting in the calculation of KBSS_SZ to be thrown off. Up until now,
this has gone unnoticed as it only affects the appended DTB case, but
pending changes for ARM in the way the decompressed kernel is cleaned
from the caches has uncovered this problem.
On a ld.lld build:
$ nm vmlinux |grep bss_
c1c22034 D __bss_start
c1c86e98 B __bss_stop
resulting in
$ readelf -s arch/arm/boot/compressed/vmlinux | grep bss_size
433: c1c86e98 0 NOTYPE GLOBAL DEFAULT ABS _kernel_bss_size
which is obviously incorrect, and may cause the cache clean to access
unmapped memory, or cause the size calculation to wrap, resulting in no
cache clean to be performed at all.
Fix this by updating the sed regex to take D type symbols into account.
Link: https://lore.kernel.org/linux-arm-kernel/6c65bcef-d4e7-25fa-43cf-2c435bb61bb9@collabora.com/
Link: https://lore.kernel.org/linux-arm-kernel/20210205085220.31232-1-ardb@kernel.org/
Cc: <stable@vger.kernel.org> # v4.19+
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Reported-by: Guillaume Tucker <guillaume.tucker@collabora.com>
Reported-by: "kernelci.org bot" <bot@kernelci.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
- Generalise byte swapping assembly
- Update debug addresses for STI
- Validate start of physical memory with DTB
- Do not clear SCTLR.nTLSMD in decompressor
- amba/locomo/sa1111 devices remove method return type is void
- address markers for KASAN in page table dump
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Merge tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm
Pull ARM updates from Russell King:
- Generalise byte swapping assembly
- Update debug addresses for STI
- Validate start of physical memory with DTB
- Do not clear SCTLR.nTLSMD in decompressor
- amba/locomo/sa1111 devices remove method return type is void
- address markers for KASAN in page table dump
* tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm:
ARM: 9065/1: OABI compat: fix build when EPOLL is not enabled
ARM: 9055/1: mailbox: arm_mhuv2: make remove callback return void
amba: Make use of bus_type functions
amba: Make the remove callback return void
vfio: platform: simplify device removal
amba: reorder functions
amba: Fix resource leak for drivers without .remove
ARM: 9054/1: arch/arm/mm/mmu.c: Remove duplicate header
ARM: 9053/1: arm/mm/ptdump:Add address markers for KASAN regions
ARM: 9051/1: vdso: remove unneded extra-y addition
ARM: 9050/1: Kconfig: Select ARCH_HAVE_NMI_SAFE_CMPXCHG where possible
ARM: 9049/1: locomo: make locomo bus's remove callback return void
ARM: 9048/1: sa1111: make sa1111 bus's remove callback return void
ARM: 9047/1: smp: remove unused variable
ARM: 9046/1: decompressor: Do not clear SCTLR.nTLSMD for ARMv7+ cores
ARM: 9045/1: uncompress: Validate start of physical memory against passed DTB
ARM: 9042/1: debug: no uncompress debugging while semihosting
ARM: 9041/1: sti LL_UART: add STiH418 SBC UART0 support
ARM: 9040/1: use DEBUG_UART_PHYS and DEBUG_UART_VIRT for sti LL_UART
ARM: 9039/1: assembler: generalize byte swapping macro into rev_l
It was observed that decompressor running on hardware implementing ARM v8.2
Load/Store Multiple Atomicity and Ordering Control (LSMAOC), say, as guest,
would stuck just after:
Uncompressing Linux... done, booting the kernel.
The reason is that it clears nTLSMD bit when disabling caches:
nTLSMD, bit [3]
When ARMv8.2-LSMAOC is implemented:
No Trap Load Multiple and Store Multiple to
Device-nGRE/Device-nGnRE/Device-nGnRnE memory.
0b0 All memory accesses by A32 and T32 Load Multiple and Store
Multiple at EL1 or EL0 that are marked at stage 1 as
Device-nGRE/Device-nGnRE/Device-nGnRnE memory are trapped and
generate a stage 1 Alignment fault.
0b1 All memory accesses by A32 and T32 Load Multiple and Store
Multiple at EL1 or EL0 that are marked at stage 1 as
Device-nGRE/Device-nGnRE/Device-nGnRnE memory are not trapped.
This bit is permitted to be cached in a TLB.
This field resets to 1.
Otherwise:
Reserved, RES1
So as effect we start getting traps we are not quite ready for.
Looking into history it seems that mask used for SCTLR clear came from
the similar code for ARMv4, where bit[3] is the enable/disable bit for
the write buffer. That not applicable to ARMv7 and onwards, so retire
that bit from the masks.
Fixes: 7d09e85448 ("[ARM] 4393/2: ARMv7: Add uncompressing code for the new CPU Id format")
Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Currently, the start address of physical memory is obtained by masking
the program counter with a fixed mask of 0xf8000000. This mask value
was chosen as a balance between the requirements of different platforms.
However, this does require that the start address of physical memory is
a multiple of 128 MiB, precluding booting Linux on platforms where this
requirement is not fulfilled.
Fix this limitation by validating the masked address against the memory
information in the passed DTB. Only use the start address
from DTB when masking would yield an out-of-range address, prefer the
traditional method in all other cases. Note that this applies only to the
explicitly passed DTB on modern systems, and not to a DTB appended to
the kernel, or to ATAGS. The appended DTB may need to be augmented by
information from ATAGS, which may need to rely on knowledge of the start
address of physical memory itself.
This allows to boot Linux on r7s9210/rza2mevb using the 64 MiB of SDRAM
on the RZA2MEVB sub board, which is located at 0x0C000000 (CS3 space),
i.e. not at a multiple of 128 MiB.
Suggested-by: Nicolas Pitre <nico@fluxnic.net>
Suggested-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Take the 4 instruction byte swapping sequence from the decompressor's
head.S, and turn it into a rev_l GAS macro for general use. While
at it, make it use the 'rev' instruction when compiling for v6 or
later.
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Commit 7536c7e03e ("of/fdt: Remove redundant kbasename function
call") exposed a bug creating DT nodes in the ATAGS to DT fixup code.
Non-existent nodes would mistaken get created with a leading '/'. The
problem was fdt_path_offset() takes a full path while creating a node
with fdt_add_subnode() takes just the basename.
Since this we only add root child nodes, we can just skip over the '/'.
Fixes: 7536c7e03e ("of/fdt: Remove redundant kbasename function call")
Reported-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Cc: Qi Zheng <arch0.zheng@gmail.com>
Cc: Russell King <linux@armlinux.org.uk>
Signed-off-by: Rob Herring <robh@kernel.org>
Tested-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Link: https://lore.kernel.org/r/20210126023905.1631161-1-robh@kernel.org
- Rework phys/virt translation
- Add KASan support
- Move DT out of linear map region
- Use more PC-relative addressing in assembly
- Remove FP emulation handling while in kernel mode
- Link with '-z norelro'
- remove old check for GCC <= 4.2 in ARM unwinder code
- disable big endian if using clang's linker
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Merge tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux
Pull ARM updates from Russell King:
- Rework phys/virt translation
- Add KASan support
- Move DT out of linear map region
- Use more PC-relative addressing in assembly
- Remove FP emulation handling while in kernel mode
- Link with '-z norelro'
- remove old check for GCC <= 4.2 in ARM unwinder code
- disable big endian if using clang's linker
* tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm: (46 commits)
ARM: 9027/1: head.S: explicitly map DT even if it lives in the first physical section
ARM: 9038/1: Link with '-z norelro'
ARM: 9037/1: uncompress: Add OF_DT_MAGIC macro
ARM: 9036/1: uncompress: Fix dbgadtb size parameter name
ARM: 9035/1: uncompress: Add be32tocpu macro
ARM: 9033/1: arm/smp: Drop the macro S(x,s)
ARM: 9032/1: arm/mm: Convert PUD level pgtable helper macros into functions
ARM: 9031/1: hyp-stub: remove unused .L__boot_cpu_mode_offset symbol
ARM: 9044/1: vfp: use undef hook for VFP support detection
ARM: 9034/1: __div64_32(): straighten up inline asm constraints
ARM: 9030/1: entry: omit FP emulation for UND exceptions taken in kernel mode
ARM: 9029/1: Make iwmmxt.S support Clang's integrated assembler
ARM: 9028/1: disable KASAN in call stack capturing routines
ARM: 9026/1: unwind: remove old check for GCC <= 4.2
ARM: 9025/1: Kconfig: CPU_BIG_ENDIAN depends on !LD_IS_LLD
ARM: 9024/1: Drop useless cast of "u64" to "long long"
ARM: 9023/1: Spelling s/mmeory/memory/
ARM: 9022/1: Change arch/arm/lib/mem*.S to use WEAK instead of .weak
ARM: kvm: replace open coded VA->PA calculations with adr_l call
ARM: head.S: use PC relative insn sequence to calculate PHYS_OFFSET
...
The DTB magic marker is stored as a 32-bit big-endian value, and thus
depends on the CPU's endianness. Add a macro to define this value in
native endianness, to reduce #ifdef clutter and (future) duplication.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
The dbgadtb macro is passed the size of the appended DTB, not the end
address.
Fixes: c03e41470e ("ARM: 9010/1: uncompress: Print the location of appended DTB")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
DTB stores all values as 32-bit big-endian integers.
Add a macro to convert such values to native CPU endianness, to reduce
duplication.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Currently, '--orphan-handling=warn' is spread out across four different
architectures in their respective Makefiles, which makes it a little
unruly to deal with in case it needs to be disabled for a specific
linker version (in this case, ld.lld 10.0.1).
To make it easier to control this, hoist this warning into Kconfig and
the main Makefile so that disabling it is simpler, as the warning will
only be enabled in a couple places (main Makefile and a couple of
compressed boot folders that blow away LDFLAGS_vmlinx) and making it
conditional is easier due to Kconfig syntax. One small additional
benefit of this is saving a call to ld-option on incremental builds
because we will have already evaluated it for CONFIG_LD_ORPHAN_WARN.
To keep the list of supported architectures the same, introduce
CONFIG_ARCH_WANT_LD_ORPHAN_WARN, which an architecture can select to
gain this automatically after all of the sections are specified and size
asserted. A special thanks to Kees Cook for the help text on this
config.
Link: https://github.com/ClangBuiltLinux/linux/issues/1187
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Replace the open coded calculations of the actual physical address
of the KVM stub vector table with a single adr_l invocation.
Reviewed-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
The ARM 'adrl' pseudo instruction is a bit problematic, as it does not
exist in Thumb mode, and it is not implemented by Clang either. Since
the Thumb variant has a slightly bigger range, it is sometimes necessary
to emit the 'adrl' variant in ARM mode where Thumb mode can use adr just
fine. However, that still leaves the Clang issue, which does not appear
to be supporting this any time soon.
So let's switch to the adr_l macro, which works for both ARM and Thumb,
and has unlimited range.
Reviewed-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Functions like memset()/memmove()/memcpy() do a lot of memory
accesses.
If a bad pointer is passed to one of these functions it is important
to catch this. Compiler instrumentation cannot do this since these
functions are written in assembly.
KASan replaces these memory functions with instrumented variants.
The original functions are declared as weak symbols so that
the strong definitions in mm/kasan/kasan.c can replace them.
The original functions have aliases with a '__' prefix in their
name, so we can call the non-instrumented variant if needed.
We must use __memcpy()/__memset() in place of memcpy()/memset()
when we copy .data to RAM and when we clear .bss, because
kasan_early_init cannot be called before the initialization of
.data and .bss.
For the kernel compression and EFI libstub's custom string
libraries we need a special quirk: even if these are built
without KASan enabled, they rely on the global headers for their
custom string libraries, which means that e.g. memcpy()
will be defined to __memcpy() and we get link failures.
Since these implementations are written i C rather than
assembly we use e.g. __alias(memcpy) to redirected any
users back to the local implementation.
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: kasan-dev@googlegroups.com
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Ard Biesheuvel <ardb@kernel.org> # QEMU/KVM/mach-virt/LPAE/8G
Tested-by: Florian Fainelli <f.fainelli@gmail.com> # Brahma SoCs
Tested-by: Ahmad Fatoum <a.fatoum@pengutronix.de> # i.MX6Q
Reported-by: Russell King - ARM Linux <rmk+kernel@armlinux.org.uk>
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Abbott Liu <liuwenliang@huawei.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Disable instrumentation for arch/arm/boot/compressed/*
since that code is executed before the kernel has even
set up its mappings and definately out of scope for
KASan.
Disable instrumentation of arch/arm/vdso/* because that code
is not linked with the kernel image, so the KASan management
code would fail to link.
Disable instrumentation of arch/arm/mm/physaddr.c. See commit
ec6d06efb0 ("arm64: Add support for CONFIG_DEBUG_VIRTUAL")
for more details.
Disable kasan check in the function unwind_pop_register because
it does not matter that kasan checks failed when unwind_pop_register()
reads the stack memory of a task.
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: kasan-dev@googlegroups.com
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Ard Biesheuvel <ardb@kernel.org> # QEMU/KVM/mach-virt/LPAE/8G
Tested-by: Florian Fainelli <f.fainelli@gmail.com> # Brahma SoCs
Tested-by: Ahmad Fatoum <a.fatoum@pengutronix.de> # i.MX6Q
Reported-by: Florian Fainelli <f.fainelli@gmail.com>
Reported-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Abbott Liu <liuwenliang@huawei.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Commit
db227c19e6 ("ARM: 8985/1: efi/decompressor: deal with HYP mode boot gracefully")
updated the EFI entry code to permit firmware to invoke the EFI stub
loader in HYP mode, with the MMU either enabled or disabled, neither
of which is permitted by the EFI spec, but which does happen in the
field.
In the MMU on case, we remain in HYP mode as configured by the firmware,
and rely on the fact that any HVC instruction issued in this mode will
be dispatched via the SVC slot in the HYP vector table. However, this
slot will point to a Thumb2 symbol if the kernel is built in Thumb2
mode, and so we have to configure HSCTLR to ensure that the exception
handlers are invoked in Thumb2 mode as well.
Fixes: db227c19e6 ("ARM: 8985/1: efi/decompressor: deal with HYP mode boot gracefully")
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Add the TEXT_OFFSET to the decompressor's kexec image structure to
kexec knows what offset to use.
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
When using the kernel with an appended DTB it is useful to
know where this will end up in the physical memory at the
time the kernel boots.
We add a debug print macro that will help out with this.
Here is a sample debug print after passing -DDEBUG to head.S
during compilation:
DTB:0x40CEBA70 (0x000051B5)
C:0x402080C0-0x40CF0CE0->0x41801D00-0x422EA920
DTB:0x422E56B0 (0x00005262)
This means that the appended DTB is first found after the
compressed kernel at 0x40CEBA70 of size 0x51B5 and then
after the compressed kernel is moved to 0x41801D00
it is found again at 0x422E56B0 and is there size 0x5262.
The growth in size of the FDT is due to the call to
atags_to_fdt() that augments the DTB with ATAG information.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
The assembly file head.S includes some debug code that does
not get enabled when we select CONFIG_DEBUG_UNCOMPRESS.
The debug in head.S relies on the user tagging on -DDEBUG
on the compilation command line.
To simplify debugging, tag on -DDEBUG so that we also get
these debug messages when selecting CONFIG_DEBUG_UNCOMPRESS.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
This drops some whitespace from the debug message about
where we move the compressed kernel: r after the message
is completely surplus since the putc routine will anyway
add r after n, and the initial linefeed just assumes
that this will always be the first message on the console,
which is not certain to be true.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
For some platforms such as Qualcomm we need to wait for the
UART to be ready before writing characters to the UART
in the same manner as the macro in debug.S used with the
main "Uncompressing Linux ..." text. Pass an extra temporary
variable to writeb and make it call waituarttxrdy and
busyuart just like the other decomression messages.
Optionally it will also call waituartcts if and only if
CONFIG_DEBUG_UART_FLOW_CONTROL is selected.
After this the decompression debug messages work fine on
Qualcomm platforms if you compile head.S with -DDEBUG.
Cc: Nicolas Pitre <nico@fluxnic.net>
Cc: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Instead of a flow control selection mechanism specifically for
8250, make this available for all debug UARTs. If the debug
UART supports waiting for CTS to be asserted, then this code
can be activated for terminals that need it.
We keep the defaults for EBSA110, Footbridge, Gemini and RPC
so that this still works as expected for these older platforms:
they assume that flow control shall be enabled for debug
prints.
I switch the location of the check for
ifdef CONFIG_DEBUG_UART_FLOW_CONTROL from the actual debug
UART drivers: the code would get compiled-out for 8250 and
Tegra unless their custom config (or passing -DFLOW_CONTROL
in the Tegra case) was not set. Instead this is conditional
at the three places where we print debug messages. The idea
is that debug UARTs can be implemented without this ifdef
boilerplate so they look cleaner, alas the ifdef has to be
somewhere.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
This patch was triggered by a remark from Russell that
introducing a call to the waituart (needed to fix debug prints
on the Qualcomm platforms) was dangerous because in some cases
this will involve waiting for a modem CTS (clear to send)
signal, and debug messages would maybe not work on platforms
with no modem connected to the UART port: they will just
hang waiting for the modem to assert CTS and this might never
happen.
Looking through all UART debug drivers implementing the waituart
macro I discovered that all users except two actually use this
macro to check if the UART is ready for TX, let's call this
TXRDY.
Only two debug UART drivers actually check for CTS:
- arch/arm/include/debug/8250.S
- arch/arm/include/debug/tegra.S
The former is very significant since the 8250 is possibly
the most common UART on the planet.
We have the following problem: the semantics of waituart are
ambiguous making it dangerous to introduce the macro to debug
code fixing debug prints for Qualcomm. To start to pry this
problem apart, this patch does the following:
- Convert all debug UART drivers to define two macros:
- waituartcts with the clear semantic to wait for CTS
to be asserted
- waituarttxrdy with the clear semantic to wait for the TX
capability of the UART to be ready
- When doing this take care to assign the right function to
each drivers macro, so they now do exactly the above.
- Update the three sites in the kernel invoking the waituart
macro to call waituartcts/waituarttxrdy in sequence, so that
the functional impact on the kernel should be zero.
After this we can start to change the code sites using this
code to do the right thing.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
The debug macros debug_reloc_start and debug_reloc_end were
rendered unused in commit 6d7d0ae515
"ARM: 6750/1: improvements to compressed/head.S".
Later on a different debug macro named dbgkc was introduced
in commit f3c899927e
"ARM: 8786/1: Debug kernel copy by printing".
Delete the dead debug code.
Cc: Nicolas Pitre <nico@fluxnic.net>
Cc: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
We don't want to depend on the linker's orphan section placement
heuristics as these can vary between linkers, and may change between
versions. All sections need to be explicitly handled in the linker script.
With all sections now handled, enable orphan section warning.
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lore.kernel.org/r/20200902025347.2504702-4-keescook@chromium.org
In preparation for warning on orphan sections, use common macros for
debug sections, discards, and text stubs. Add discards for unwanted .note,
and .rel sections.
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Russell King <linux@armlinux.org.uk>
Link: https://lore.kernel.org/r/20200821194310.3089815-21-keescook@chromium.org
CFLAGS_REMOVE_<file>.o filters out flags when compiling a particular
object, but there is no convenient way to do that for every object in
a directory.
Add ccflags-remove-y and asflags-remove-y to make it easily.
Use ccflags-remove-y to clean up some Makefiles.
The add/remove order works as follows:
[1] KBUILD_CFLAGS specifies compiler flags used globally
[2] ccflags-y adds compiler flags for all objects in the
current Makefile
[3] ccflags-remove-y removes compiler flags for all objects in the
current Makefile (New feature)
[4] CFLAGS_<file> adds compiler flags per file.
[5] CFLAGS_REMOVE_<file> removes compiler flags per file.
Having [3] before [4] allows us to remove flags from most (but not all)
objects in the current Makefile.
For example, kernel/trace/Makefile removes $(CC_FLAGS_FTRACE)
from all objects in the directory, then adds it back to
trace_selftest_dynamic.o and CFLAGS_trace_kprobe_selftest.o
The same applies to lib/livepatch/Makefile.
Please note ccflags-remove-y has no effect to the sub-directories.
In contrast, the previous notation got rid of compiler flags also from
all the sub-directories.
The following are not affected because they have no sub-directories:
arch/arm/boot/compressed/
arch/powerpc/xmon/
arch/sh/
kernel/trace/
However, lib/ has several sub-directories.
To keep the behavior, I added ccflags-remove-y to all Makefiles
in subdirectories of lib/, except the following:
lib/vdso/Makefile - Kbuild does not descend into this Makefile
lib/raid/test/Makefile - This is not used for the kernel build
I think commit 2464a609de ("ftrace: do not trace library functions")
excluded too much. In the next commit, I will remove ccflags-remove-y
from the sub-directories of lib/.
Suggested-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Acked-by: Brendan Higgins <brendanhiggins@google.com> (KUnit)
Tested-by: Anders Roxell <anders.roxell@linaro.org>
Some Makefiles already pass -fno-stack-protector unconditionally.
For example, arch/arm64/kernel/vdso/Makefile, arch/x86/xen/Makefile.
No problem report so far about hard-coding this option. So, we can
assume all supported compilers know -fno-stack-protector.
GCC 4.8 and Clang support this option (https://godbolt.org/z/_HDGzN)
Get rid of cc-option from -fno-stack-protector.
Remove CONFIG_CC_HAS_STACKPROTECTOR_NONE, which is always 'y'.
Note:
arch/mips/vdso/Makefile adds -fno-stack-protector twice, first
unconditionally, and second conditionally. I removed the second one.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
EFI on ARM only supports short descriptors, and given that it mandates
that the MMU and caches are on, it is implied that booting in HYP mode
is not supported.
However, implementations of EFI exist (i.e., U-Boot) that ignore this
requirement, which is not entirely unreasonable, given that it makes
HYP mode inaccessible to the operating system.
So let's make sure that we can deal with this condition gracefully.
We already tolerate booting the EFI stub with the caches off (even
though this violates the EFI spec as well), and so we should deal
with HYP mode boot with MMU and caches either on or off.
- When the MMU and caches are on, we can ignore the HYP stub altogether,
since we can carry on executing at HYP. We do need to ensure that we
disable the MMU at HYP before entering the kernel proper.
- When the MMU and caches are off, we have to drop to SVC mode so that
we can set up the page tables using short descriptors. In this case,
we need to install the HYP stub as usual, so that we can return to HYP
mode before handing over to the kernel proper.
Tested-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
- remove a now unnecessary usage of the KERNEL_DS for
sys_oabi_epoll_ctl()
- update my email address in a number of drivers
- decompressor EFI updates from Ard Biesheuvel
- module unwind section handling updates
- sparsemem Kconfig cleanups
- make act_mm macro respect THREAD_SIZE
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Merge tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm
Pull ARM updates from Russell King:
- remove a now unnecessary usage of the KERNEL_DS for
sys_oabi_epoll_ctl()
- update my email address in a number of drivers
- decompressor EFI updates from Ard Biesheuvel
- module unwind section handling updates
- sparsemem Kconfig cleanups
- make act_mm macro respect THREAD_SIZE
* tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm:
ARM: 8980/1: Allow either FLATMEM or SPARSEMEM on the multiplatform build
ARM: 8979/1: Remove redundant ARCH_SPARSEMEM_DEFAULT setting
ARM: 8978/1: mm: make act_mm() respect THREAD_SIZE
ARM: decompressor: run decompressor in place if loaded via UEFI
ARM: decompressor: move GOT into .data for EFI enabled builds
ARM: decompressor: defer loading of the contents of the LC0 structure
ARM: decompressor: split off _edata and stack base into separate object
ARM: decompressor: move headroom variable out of LC0
ARM: 8976/1: module: allow arch overrides for .init section names
ARM: 8975/1: module: fix handling of unwind init sections
ARM: 8974/1: use SPARSMEM_STATIC when SPARSEMEM is enabled
ARM: 8971/1: replace the sole use of a symbol with its definition
ARM: 8969/1: decompressor: simplify libfdt builds
Update rmk's email address in various drivers
ARM: compat: remove KERNEL_DS usage in sys_oabi_epoll_ctl()
- preliminary changes for RISC-V
- Add support for setting the resolution on the EFI framebuffer
- Simplify kernel image loading for arm64
- Move .bss into .data via the linker script instead of relying on symbol
annotations.
- Get rid of __pure getters to access global variables
- Clean up the config table matching arrays
- Rename pr_efi/pr_efi_err to efi_info/efi_err, and use them consistently
- Simplify and unify initrd loading
- Parse the builtin command line on x86 (if provided)
- Implement printk() support, including support for wide character strings
- Simplify GDT handling in early mixed mode thunking code
- Some other minor fixes and cleanups
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'efi-core-2020-06-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull EFI updates from Ingo Molnar:
"The EFI changes for this cycle are:
- preliminary changes for RISC-V
- Add support for setting the resolution on the EFI framebuffer
- Simplify kernel image loading for arm64
- Move .bss into .data via the linker script instead of relying on
symbol annotations.
- Get rid of __pure getters to access global variables
- Clean up the config table matching arrays
- Rename pr_efi/pr_efi_err to efi_info/efi_err, and use them
consistently
- Simplify and unify initrd loading
- Parse the builtin command line on x86 (if provided)
- Implement printk() support, including support for wide character
strings
- Simplify GDT handling in early mixed mode thunking code
- Some other minor fixes and cleanups"
* tag 'efi-core-2020-06-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (79 commits)
efi/x86: Don't blow away existing initrd
efi/x86: Drop the special GDT for the EFI thunk
efi/libstub: Add missing prototype for PE/COFF entry point
efi/efivars: Add missing kobject_put() in sysfs entry creation error path
efi/libstub: Use pool allocation for the command line
efi/libstub: Don't parse overlong command lines
efi/libstub: Use snprintf with %ls to convert the command line
efi/libstub: Get the exact UTF-8 length
efi/libstub: Use %ls for filename
efi/libstub: Add UTF-8 decoding to efi_puts
efi/printf: Add support for wchar_t (UTF-16)
efi/gop: Add an option to list out the available GOP modes
efi/libstub: Add definitions for console input and events
efi/libstub: Implement printk-style logging
efi/printf: Turn vsprintf into vsnprintf
efi/printf: Abort on invalid format
efi/printf: Refactor code to consolidate padding and output
efi/printf: Handle null string input
efi/printf: Factor out integer argument retrieval
efi/printf: Factor out width/precision parsing
...
- correct value of decompressor tag size in header
- fix DACR value when we have nested exceptions
- fix a missing newline on a kernel message
- fix mask for ptrace thumb breakpoint hook
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Merge tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm
Pull ARM fixes from Russell King:
- correct value of decompressor tag size in header
- fix DACR value when we have nested exceptions
- fix a missing newline on a kernel message
- fix mask for ptrace thumb breakpoint hook
* tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm:
ARM: 8977/1: ptrace: Fix mask for thumb breakpoint hook
ARM: 8973/1: Add missing newline terminator to kernel message
ARM: uaccess: fix DACR mismatch with nested exceptions
ARM: uaccess: integrate uaccess_save and uaccess_restore
ARM: uaccess: consolidate uaccess asm to asm/uaccess-asm.h
ARM: 8970/1: decompressor: increase tag size
Fix a missing prototype warning by adding a forward declaration
for the PE/COFF entrypoint, and while at it, align the function
name between the x86 and ARM versions of the stub.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
The decompressor can load from anywhere in memory, and the only reason
the EFI stub code relocates it is to ensure it appears within the first
128 MiB of memory, so that the uncompressed kernel ends up at the right
offset in memory.
We can short circuit this, and simply jump into the decompressor startup
code at the point where it knows where the base of memory lives. This
also means there is no need to disable the MMU and caches, create new
page tables and re-enable them.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Nicolas Pitre <nico@fluxnic.net>
We will be running the decompressor in place after a future patch,
instead of copying it around first. This means we no longer have to
disable and re-enable the MMU and caches either. However, this means
we will be loaded with the restricted permissions set by the UEFI
firmware, which means that we have to move the GOT table into the
data section in order for the contents to be writable by the code
itself.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Nicolas Pitre <nico@fluxnic.net>
The remaining contents of LC0 are only used after the point in the
decompressor startup code where we enter via 'wont_overwrite'. So
move the loading of the LC0 structure after it. This will allow us
to jump to wont_overwrite directly from the EFI stub, and execute
the decompressor in place at the offset it was loaded by the UEFI
firmware.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Nicolas Pitre <nico@fluxnic.net>
