Commit Graph

59 Commits

Author SHA1 Message Date
Charlie Jenkins
4525462dd0
riscv: lib: Check if output in asm goto supported
The output field of an asm goto statement is not supported by all
compilers. If it is not supported, fallback to the non-optimized code.

Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>
Fixes: a04c192eab ("riscv: Add checksum library")
Link: https://lore.kernel.org/r/20240118-csum_remove_output_operands_asm_goto-v2-1-5d1b73cf93d4@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-01-18 14:41:38 -08:00
Palmer Dabbelt
c640868491
Merge patch series "riscv: Add fine-tuned checksum functions"
Charlie Jenkins <charlie@rivosinc.com> says:

Each architecture generally implements fine-tuned checksum functions to
leverage the instruction set. This patch adds the main checksum
functions that are used in networking. Tested on QEMU, this series
allows the CHECKSUM_KUNIT tests to complete an average of 50.9% faster.

This patch takes heavy use of the Zbb extension using alternatives
patching.

To test this patch, enable the configs for KUNIT, then CHECKSUM_KUNIT.

I have attempted to make these functions as optimal as possible, but I
have not ran anything on actual riscv hardware. My performance testing
has been limited to inspecting the assembly, running the algorithms on
x86 hardware, and running in QEMU.

ip_fast_csum is a relatively small function so even though it is
possible to read 64 bits at a time on compatible hardware, the
bottleneck becomes the clean up and setup code so loading 32 bits at a
time is actually faster.

* b4-shazam-merge:
  kunit: Add tests for csum_ipv6_magic and ip_fast_csum
  riscv: Add checksum library
  riscv: Add checksum header
  riscv: Add static key for misaligned accesses
  asm-generic: Improve csum_fold

Link: https://lore.kernel.org/r/20240108-optimize_checksum-v15-0-1c50de5f2167@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-01-17 18:07:11 -08:00
Charlie Jenkins
a04c192eab
riscv: Add checksum library
Provide a 32 and 64 bit version of do_csum. When compiled for 32-bit
will load from the buffer in groups of 32 bits, and when compiled for
64-bit will load in groups of 64 bits.

Additionally provide riscv optimized implementation of csum_ipv6_magic.

Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Xiao Wang <xiao.w.wang@intel.com>
Link: https://lore.kernel.org/r/20240108-optimize_checksum-v15-4-1c50de5f2167@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-01-17 17:52:32 -08:00
Palmer Dabbelt
a894e8ed09
Merge patch series "riscv: support kernel-mode Vector"
Andy Chiu <andy.chiu@sifive.com> says:

This series provides support running Vector in kernel mode.
Additionally, kernel-mode Vector can be configured to run without
turnning off preemption on a CONFIG_PREEMPT kernel. Along with the
suport, we add Vector optimized copy_{to,from}_user. And provide a
simple threshold to decide when to run the vectorized functions.

We decided to drop vectorized memcpy/memset/memmove for the moment due
to the concern of memory side-effect in kernel_vector_begin(). The
detailed description can be found at v9[0]

This series is composed by 4 parts:
 patch 1-4: adds basic support for kernel-mode Vector
 patch 5: includes vectorized copy_{to,from}_user into the kernel
 patch 6: refactor context switch code in fpu [1]
 patch 7-10: provides some code refactors and support for preemptible
             kernel-mode Vector.

This series can be merged if we feel any part of {1~4, 5, 6, 7~10} is
mature enough.

This patch is tested on a QEMU with V and verified that booting, normal
userspace operations all work as usual with thresholds set to 0. Also,
we test by launching multiple kernel threads which continuously executes
and verifies Vector operations in the background. The module that tests
these operation is expected to be upstream later.

* b4-shazam-merge:
  riscv: vector: allow kernel-mode Vector with preemption
  riscv: vector: use kmem_cache to manage vector context
  riscv: vector: use a mask to write vstate_ctrl
  riscv: vector: do not pass task_struct into riscv_v_vstate_{save,restore}()
  riscv: fpu: drop SR_SD bit checking
  riscv: lib: vectorize copy_to_user/copy_from_user
  riscv: sched: defer restoring Vector context for user
  riscv: Add vector extension XOR implementation
  riscv: vector: make Vector always available for softirq context
  riscv: Add support for kernel mode vector

Link: https://lore.kernel.org/r/20240115055929.4736-1-andy.chiu@sifive.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-01-16 07:14:04 -08:00
Andy Chiu
c2a658d419
riscv: lib: vectorize copy_to_user/copy_from_user
This patch utilizes Vector to perform copy_to_user/copy_from_user. If
Vector is available and the size of copy is large enough for Vector to
perform better than scalar, then direct the kernel to do Vector copies
for userspace. Though the best programming practice for users is to
reduce the copy, this provides a faster variant when copies are
inevitable.

The optimal size for using Vector, copy_to_user_thres, is only a
heuristic for now. We can add DT parsing if people feel the need of
customizing it.

The exception fixup code of the __asm_vector_usercopy must fallback to
the scalar one because accessing user pages might fault, and must be
sleepable. Current kernel-mode Vector does not allow tasks to be
preemptible, so we must disactivate Vector and perform a scalar fallback
in such case.

The original implementation of Vector operations comes from
https://github.com/sifive/sifive-libc, which we agree to contribute to
Linux kernel.

Co-developed-by: Jerry Shih <jerry.shih@sifive.com>
Signed-off-by: Jerry Shih <jerry.shih@sifive.com>
Co-developed-by: Nick Knight <nick.knight@sifive.com>
Signed-off-by: Nick Knight <nick.knight@sifive.com>
Suggested-by: Guo Ren <guoren@kernel.org>
Signed-off-by: Andy Chiu <andy.chiu@sifive.com>
Tested-by: Björn Töpel <bjorn@rivosinc.com>
Tested-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Link: https://lore.kernel.org/r/20240115055929.4736-6-andy.chiu@sifive.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-01-16 07:13:57 -08:00
Greentime Hu
c5674d00ca
riscv: Add vector extension XOR implementation
This patch adds support for vector optimized XOR and it is tested in
qemu.

Co-developed-by: Han-Kuan Chen <hankuan.chen@sifive.com>
Signed-off-by: Han-Kuan Chen <hankuan.chen@sifive.com>
Signed-off-by: Greentime Hu <greentime.hu@sifive.com>
Signed-off-by: Andy Chiu <andy.chiu@sifive.com>
Tested-by: Björn Töpel <bjorn@rivosinc.com>
Tested-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Link: https://lore.kernel.org/r/20240115055929.4736-4-andy.chiu@sifive.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-01-16 07:13:55 -08:00
Al Viro
62694797f5
use linux/export.h rather than asm-generic/export.h
asm-generic/export.h is a wrapper for linux/export.h, with explicit request
to use linux/export.h directly.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Link: https://lore.kernel.org/r/20231214191922.GQ1674809@ZenIV
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-01-09 20:10:40 -08:00
Clément Léger
76329c6939
riscv: Use SYM_*() assembly macros instead of deprecated ones
ENTRY()/END()/WEAK() macros are deprecated and we should make use of the
new SYM_*() macros [1] for better annotation of symbols. Replace the
deprecated ones with the new ones and fix wrong usage of END()/ENDPROC()
to correctly describe the symbols.

[1] https://docs.kernel.org/core-api/asm-annotations.html

Signed-off-by: Clément Léger <cleger@rivosinc.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20231024132655.730417-3-cleger@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2023-11-06 09:42:47 -08:00
Clément Léger
b18f7296fb
riscv: use ".L" local labels in assembly when applicable
For the sake of coherency, use local labels in assembly when
applicable. This also avoid kprobes being confused when applying a
kprobe since the size of function is computed by checking where the
next visible symbol is located. This might end up in computing some
function size to be way shorter than expected and thus failing to apply
kprobes to the specified offset.

Signed-off-by: Clément Léger <cleger@rivosinc.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20231024132655.730417-2-cleger@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2023-11-06 09:42:05 -08:00
Conor Dooley
d3eabf2f2c
RISC-V: capitalise CMO op macros
The CMO op macros initially used lower case, as the original iteration
of the ALT_CMO_OP alternative stringified the first parameter to
finalise the assembly for the standard variant.
As a knock-on, the T-Head versions of these CMOs had to use mixed case
defines. Commit dd23e95358 ("RISC-V: replace cbom instructions with
an insn-def") removed the asm construction with stringify, replacing it
an insn-def macro, rending the lower-case surplus to requirements.
As far as I can tell from a brief check, CBO_zero does not see similar
use and didn't require the mixed case define in the first place.
Replace the lower case characters now for consistency with other
insn-def macros in the standard and T-Head forms, and adjust the
callsites.

Suggested-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20230915-aloe-dollar-994937477776@spud
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2023-11-05 09:11:23 -08:00
Alexandre Ghiti
4b05b99390
riscv: uaccess: Return the number of bytes effectively not copied
It was reported that the riscv kernel hangs while executing the test
in [1].

Indeed, the test hangs when trying to write a buffer to a file. The
problem is that the riscv implementation of raw_copy_from_user() does not
return the correct number of bytes not written when an exception happens
and is fixed up, instead it always returns the initial size to copy,
even if some bytes were actually copied.

generic_perform_write() pre-faults the user pages and bails out if nothing
can be written, otherwise it will access the userspace buffer: here the
riscv implementation keeps returning it was not able to copy any byte
though the pre-faulting indicates otherwise. So generic_perform_write()
keeps retrying to access the user memory and ends up in an infinite
loop.

Note that before the commit mentioned in [1] that introduced this
regression, it worked because generic_perform_write() would bail out if
only one byte could not be written.

So fix this by returning the number of bytes effectively not written in
__asm_copy_[to|from]_user() and __clear_user(), as it is expected.

Link: https://lore.kernel.org/linux-riscv/20230309151841.bomov6hq3ybyp42a@debian/ [1]
Fixes: ebcbd75e39 ("riscv: Fix the bug in memory access fixup code")
Reported-by: Bo YU <tsu.yubo@gmail.com>
Closes: https://lore.kernel.org/linux-riscv/20230309151841.bomov6hq3ybyp42a@debian/#t
Reported-by: Aurelien Jarno <aurelien@aurel32.net>
Closes: https://lore.kernel.org/linux-riscv/ZNOnCakhwIeue3yr@aurel32.net/
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Reviewed-by: Björn Töpel <bjorn@rivosinc.com>
Tested-by: Aurelien Jarno <aurelien@aurel32.net>
Reviewed-by: Aurelien Jarno <aurelien@aurel32.net>
Link: https://lore.kernel.org/r/20230811150604.1621784-1-alexghiti@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2023-08-16 07:30:06 -07:00
Alexandre Ghiti
26e7aacb83
riscv: Allow to downgrade paging mode from the command line
Add 2 early command line parameters that allow to downgrade satp mode
(using the same naming as x86):
- "no5lvl": use a 4-level page table (down from sv57 to sv48)
- "no4lvl": use a 3-level page table (down from sv57/sv48 to sv39)

Note that going through the device tree to get the kernel command line
works with ACPI too since the efi stub creates a device tree anyway with
the command line.

In KASAN kernels, we can't use the libfdt that early in the boot process
since we are not ready to execute instrumented functions. So instead of
using the "generic" libfdt, we compile our own versions of those functions
that are not instrumented and that are prefixed so that they do not
conflict with the generic ones. We also need the non-instrumented versions
of the string functions and the prefixed versions of memcpy/memmove.

This is largely inspired by commit aacd149b62 ("arm64: head: avoid
relocating the kernel twice for KASLR") from which I removed compilation
flags that were not relevant to RISC-V at the moment (LTO, SCS). Also
note that we have to link with -z norelro to avoid ld.lld to throw a
warning with the new .got sections, like in commit 311bea3cb9 ("arm64:
link with -z norelro for LLD or aarch64-elf").

Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Tested-by: Björn Töpel <bjorn@rivosinc.com>
Reviewed-by: Björn Töpel <bjorn@rivosinc.com>
Link: https://lore.kernel.org/r/20230424092313.178699-2-alexghiti@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2023-04-26 07:30:52 -07:00
Andrew Jones
ab0f77465e
RISC-V: Use Zicboz in clear_page when available
Using memset() to zero a 4K page takes 563 total instructions, where
20 are branches. clear_page(), with Zicboz and a 64 byte block size,
takes 169 total instructions, where 4 are branches and 33 are nops.
Even though the block size is a variable, thanks to alternatives, we
can still implement a Duff device without having to do any preliminary
calculations. This is achieved by using the alternatives' cpufeature
value (the upper 16 bits of patch_id). The value used is the maximum
zicboz block size order accepted at the patch site. This enables us
to stop patching / unrolling when 4K bytes have been zeroed (we would
loop and continue after 4K if the page size would be larger)

For 4K pages, unrolling 16 times allows block sizes of 64 and 128 to
only loop a few times and larger block sizes to not loop at all. Since
cbo.zero doesn't take an offset, we also need an 'add' after each
instruction, making the loop body 112 to 160 bytes. Hopefully this
is small enough to not cause icache misses.

Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230224162631.405473-7-ajones@ventanamicro.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2023-03-14 21:26:06 -07:00
Andrew Jones
28ea374da1
riscv: lib: Include hwcap.h directly
When using alternatives for cpufeatures we should include hwcap.h
directly, rather than through errata_list.h. Opportunistically drop
an unused include too.

Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Heiko Stuebner <heiko.stuebner@vrull.eu>
Link: https://lore.kernel.org/r/20230224154601.88163-6-ajones@ventanamicro.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2023-03-14 20:51:24 -07:00
Björn Töpel
81a1dd10b0
riscv, lib: Fix Zbb strncmp
The Zbb optimized strncmp has two parts; a fast path that does XLEN/8B
per iteration, and a slow that does one byte per iteration.

The idea is to compare aligned XLEN chunks for most of strings, and do
the remainder tail in the slow path.

The Zbb strncmp has two issues in the fast path:

Incorrect remainder handling (wrong compare): Assume that the string
length is 9. On 64b systems, the fast path should do one iteration,
and one iteration in the slow path. Instead, both were done in the
fast path, which lead to incorrect results. An example:

  strncmp("/dev/vda", "/dev/", 5);

Correct by changing "bgt" to "bge".

Missing NULL checks in the second string: This could lead to incorrect
results for:

  strncmp("/dev/vda", "/dev/vda\0", 8);

Correct by adding an additional check.

Fixes: b6fcdb191e ("RISC-V: add zbb support to string functions")
Suggested-by: Heiko Stuebner <heiko.stuebner@vrull.eu>
Signed-off-by: Björn Töpel <bjorn@rivosinc.com>
Tested-by: Conor Dooley <conor.dooley@microchip.com>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20230228184211.1585641-1-bjorn@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2023-02-28 18:42:38 -08:00
Heiko Stuebner
6934cf8a3e
RISC-V: improve string-function assembly
Adapt the suggestions for the assembly string functions that Andrew
suggested but that I didn't manage to include into the series that
got applied.

This includes improvements to two comments, removal of unneeded labels
and moving one instruction slightly higher to contradict an
explanatory comment.

Suggested-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Heiko Stuebner <heiko.stuebner@vrull.eu>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Tested-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230208225328.1636017-3-heiko@sntech.de
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2023-02-28 08:00:34 -08:00
Samuel Holland
d5a7fab785
riscv: Fix Zbb alternative IDs
Commit 4bf8860760 ("riscv: cpufeature: extend
riscv_cpufeature_patch_func to all ISA extensions") switched ISA
extension alternatives to use the RISCV_ISA_EXT_* macros instead of
CPUFEATURE_*. This was mismerged when applied on top of the Zbb series,
so the Zbb alternatives referenced the wrong errata ID values.

Fixes: 9daca9a5b9 ("Merge patch series "riscv: improve boot time isa extensions handling"")
Signed-off-by: Samuel Holland <samuel@sholland.org>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Guo Ren <guoren@kernel.org>
Tested-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230212021534.59121-3-samuel@sholland.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2023-02-14 16:10:36 -08:00
Heiko Stuebner
b6fcdb191e
RISC-V: add zbb support to string functions
Add handling for ZBB extension and add support for using it as a
variant for optimized string functions.

Support for the Zbb-str-variants is limited to the GNU-assembler
for now, as LLVM has not yet acquired the functionality to
selectively change the arch option in assembler code.
This is still under review at
    https://reviews.llvm.org/D123515

Co-developed-by: Christoph Muellner <christoph.muellner@vrull.eu>
Signed-off-by: Christoph Muellner <christoph.muellner@vrull.eu>
Signed-off-by: Heiko Stuebner <heiko.stuebner@vrull.eu>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230113212301.3534711-3-heiko@sntech.de
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2023-01-31 11:43:24 -08:00
Heiko Stuebner
56e0790c7f
RISC-V: add infrastructure to allow different str* implementations
Depending on supported extensions on specific RISC-V cores,
optimized str* functions might make sense.

This adds basic infrastructure to allow patching the function calls
via alternatives later on.

The Linux kernel provides standard implementations for string functions
but when architectures want to extend them, they need to provide their
own.

The added generic string functions are done in assembler (taken from
disassembling the main-kernel functions for now) to allow us to control
the used registers and extend them with optimized variants.

This doesn't override the compiler's use of builtin replacements. So still
first of all the compiler will select if a builtin will be better suitable
i.e. for known strings. For all regular cases we will want to later
select possible optimized variants and in the worst case fall back to the
generic implemention added with this change.

Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Heiko Stuebner <heiko.stuebner@vrull.eu>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230113212301.3534711-2-heiko@sntech.de
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2023-01-31 11:43:23 -08:00
Chen Lifu
c08b4848f5
riscv: lib: uaccess: fix CSR_STATUS SR_SUM bit
Since commit 5d8544e2d0 ("RISC-V: Generic library routines and assembly")
and commit ebcbd75e39 ("riscv: Fix the bug in memory access fixup code"),
if __clear_user and __copy_user return from an fixup branch,
CSR_STATUS SR_SUM bit will be set, it is a vulnerability, so that
S-mode memory accesses to pages that are accessible by U-mode will success.
Disable S-mode access to U-mode memory should clear SR_SUM bit.

Fixes: 5d8544e2d0 ("RISC-V: Generic library routines and assembly")
Fixes: ebcbd75e39 ("riscv: Fix the bug in memory access fixup code")
Signed-off-by: Chen Lifu <chenlifu@huawei.com>
Reviewed-by: Ben Dooks <ben.dooks@codethink.co.uk>
Link: https://lore.kernel.org/r/20220615014714.1650349-1-chenlifu@huawei.com
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2022-08-10 14:06:31 -07:00
Michael T. Kloos
9d1f0ec9f7
riscv: Fixed misaligned memory access. Fixed pointer comparison.
Rewrote the RISC-V memmove() assembly implementation.  The
previous implementation did not check memory alignment and it
compared 2 pointers with a signed comparison.  The misaligned
memory access would cause the kernel to crash on systems that
did not emulate it in firmware and did not support it in hardware.
Firmware emulation is slow and may not exist.  The RISC-V spec
does not guarantee that support for misaligned memory accesses
will exist.  It should not be depended on.

This patch now checks for XLEN granularity of co-alignment between
the pointers.  Failing that, copying is done by loading from the 2
contiguous and naturally aligned XLEN memory locations containing
the overlapping XLEN sized data to be copied.  The data is shifted
into the correct place and binary or'ed together on each
iteration.  The result is then stored into the corresponding
naturally aligned XLEN sized location in the destination.  For
unaligned data at the terminations of the regions to be copied
or for copies less than (2 * XLEN) in size, byte copy is used.

This patch also now uses unsigned comparison for the pointers and
migrates to the newer assembler annotations from the now deprecated
ones.

Signed-off-by: Michael T. Kloos <michael@michaelkloos.com>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2022-03-10 10:24:04 -08:00
Jisheng Zhang
6dd10d9166
riscv: extable: consolidate definitions
This is a riscv port of commit 819771cc28 ("arm64: extable:
consolidate definitions").

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2022-01-05 17:52:47 -08:00
Jisheng Zhang
9d504f9aa5
riscv: lib: uaccess: fold fixups into body
uaccess functions such __asm_copy_to_user(),  __arch_copy_from_user()
and __clear_user() place their exception fixups in the `.fixup` section
without any clear association with themselves. If we backtrace the
fixup code, it will be symbolized as an offset from the nearest prior
symbol.

Similar as arm64 does, we must move fixups into the body of the
functions themselves, after the usual fast-path returns.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2022-01-05 17:52:39 -08:00
Jisheng Zhang
bb1f85d604
riscv: switch to relative exception tables
Similar as other architectures such as arm64, x86 and so on, use
offsets relative to the exception table entry values rather than
absolute addresses for both the exception locationand the fixup.

However, RISCV label difference will actually produce two relocations,
a pair of R_RISCV_ADD32 and R_RISCV_SUB32. Take below simple code for
example:

$ cat test.S
.section .text
1:
        nop
.section __ex_table,"a"
        .balign 4
        .long (1b - .)
.previous

$ riscv64-linux-gnu-gcc -c test.S
$ riscv64-linux-gnu-readelf -r test.o
Relocation section '.rela__ex_table' at offset 0x100 contains 2 entries:
  Offset          Info           Type           Sym. Value    Sym. Name + Addend
000000000000  000600000023 R_RISCV_ADD32     0000000000000000 .L1^B1 + 0
000000000000  000500000027 R_RISCV_SUB32     0000000000000000 .L0  + 0

The modpost will complain the R_RISCV_SUB32 relocation, so we need to
patch modpost.c to skip this relocation for .rela__ex_table section.

After this patch, the __ex_table section size of defconfig vmlinux is
reduced from 7072 Bytes to 3536 Bytes.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2022-01-05 17:52:20 -08:00
Andy Shevchenko
5f6286a608 include/linux/delay.h: replace kernel.h with the necessary inclusions
When kernel.h is used in the headers it adds a lot into dependency hell,
especially when there are circular dependencies are involved.

Replace kernel.h inclusion with the list of what is really being used.

[akpm@linux-foundation.org: cxd2880_common.h needs bits.h for GENMASK()]
[andriy.shevchenko@linux.intel.com: delay.h: fix for removed kernel.h]
  Link: https://lkml.kernel.org/r/20211028170143.56523-1-andriy.shevchenko@linux.intel.com
[akpm@linux-foundation.org: include/linux/fwnode.h needs bits.h for BIT()]

Link: https://lkml.kernel.org/r/20211027150324.79827-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-09 10:02:49 -08:00
Akira Tsukamoto
ea196c548c
riscv: __asm_copy_to-from_user: Fix: Typos in comments
Fixing typos and grammar mistakes and using more intuitive label
name.

Signed-off-by: Akira Tsukamoto <akira.tsukamoto@gmail.com>
Fixes: ca6eaaa210 ("riscv: __asm_copy_to-from_user: Optimize unaligned memory access and pipeline stall")
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
2021-07-23 17:49:12 -07:00
Akira Tsukamoto
d4b3e0105e
riscv: __asm_copy_to-from_user: Remove unnecessary size check
Clean up:

The size of 0 will be evaluated in the next step. Not
required here.

Signed-off-by: Akira Tsukamoto <akira.tsukamoto@gmail.com>
Fixes: ca6eaaa210 ("riscv: __asm_copy_to-from_user: Optimize unaligned memory access and pipeline stall")
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
2021-07-23 17:49:07 -07:00
Akira Tsukamoto
22b5f16ffe
riscv: __asm_copy_to-from_user: Fix: fail on RV32
Had a bug when converting bytes to bits when the cpu was rv32.

The a3 contains the number of bytes and multiple of 8
would be the bits. The LGREG is holding 2 for RV32 and 3 for
RV32, so to achieve multiple of 8 it must always be constant 3.
The 2 was mistakenly used for rv32.

Signed-off-by: Akira Tsukamoto <akira.tsukamoto@gmail.com>
Fixes: ca6eaaa210 ("riscv: __asm_copy_to-from_user: Optimize unaligned memory access and pipeline stall")
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
2021-07-23 17:49:01 -07:00
Akira Tsukamoto
6010d300f9
riscv: __asm_copy_to-from_user: Fix: overrun copy
There were two causes for the overrun memory access.

The threshold size was too small.
The aligning dst require one SZREG and unrolling word copy requires
8*SZREG, total have to be at least 9*SZREG.

Inside the unrolling copy, the subtracting -(8*SZREG-1) would make
iteration happening one extra loop. Proper value is -(8*SZREG).

Signed-off-by: Akira Tsukamoto <akira.tsukamoto@gmail.com>
Fixes: ca6eaaa210 ("riscv: __asm_copy_to-from_user: Optimize unaligned memory access and pipeline stall")
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
2021-07-23 17:48:52 -07:00
Akira Tsukamoto
ca6eaaa210
riscv: __asm_copy_to-from_user: Optimize unaligned memory access and pipeline stall
This patch will reduce cpu usage dramatically in kernel space especially
for application which use sys-call with large buffer size, such as
network applications. The main reason behind this is that every
unaligned memory access will raise exceptions and switch between s-mode
and m-mode causing large overhead.

First copy in bytes until reaches the first word aligned boundary in
destination memory address. This is the preparation before the bulk
aligned word copy.

The destination address is aligned now, but oftentimes the source
address is not in an aligned boundary. To reduce the unaligned memory
access, it reads the data from source in aligned boundaries, which will
cause the data to have an offset, and then combines the data in the next
iteration by fixing offset with shifting before writing to destination.
The majority of the improving copy speed comes from this shift copy.

In the lucky situation that the both source and destination address are
on the aligned boundary, perform load and store with register size to
copy the data. Without the unrolling, it will reduce the speed since the
next store instruction for the same register using from the load will
stall the pipeline.

At last, copying the remainder in one byte at a time.

Signed-off-by: Akira Tsukamoto <akira.tsukamoto@gmail.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
2021-07-06 15:09:48 -07:00
Guo Ren
ee55ff803b
riscv: Add support for function error injection
Inspired by the commit 42d038c4fb ("arm64: Add support for function
error injection"), this patch supports function error injection for
riscv.

This patch mainly support two functions: one is regs_set_return_value()
which is used to overwrite the return value; the another function is
override_function_with_return() which is to override the probed
function returning and jump to its caller.

Test log:
 cd /sys/kernel/debug/fail_function
 echo sys_clone > inject
 echo 100 > probability
 echo 1 > interval
 ls /
[  313.176875] FAULT_INJECTION: forcing a failure.
[  313.176875] name fail_function, interval 1, probability 100, space 0, times 1
[  313.184357] CPU: 0 PID: 87 Comm: sh Not tainted 5.8.0-rc5-00007-g6a758cc #117
[  313.187616] Call Trace:
[  313.189100] [<ffffffe0002036b6>] walk_stackframe+0x0/0xc2
[  313.191626] [<ffffffe00020395c>] show_stack+0x40/0x4c
[  313.193927] [<ffffffe000556c60>] dump_stack+0x7c/0x96
[  313.194795] [<ffffffe0005522e8>] should_fail+0x140/0x142
[  313.195923] [<ffffffe000299ffc>] fei_kprobe_handler+0x2c/0x5a
[  313.197687] [<ffffffe0009e2ec4>] kprobe_breakpoint_handler+0xb4/0x18a
[  313.200054] [<ffffffe00020357e>] do_trap_break+0x36/0xca
[  313.202147] [<ffffffe000201bca>] ret_from_exception+0x0/0xc
[  313.204556] [<ffffffe000201bbc>] ret_from_syscall+0x0/0x2
-sh: can't fork: Invalid argument

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Palmer Dabbelt <palmerdabbelt@google.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
2021-01-14 15:09:09 -08:00
Nylon Chen
04091d6c05
riscv: provide memmove implementation
The memmove used by the kernel feature like KASAN.

Signed-off-by: Nick Hu <nickhu@andestech.com>
Signed-off-by: Nick Hu <nick650823@gmail.com>
Signed-off-by: Nylon Chen <nylon7@andestech.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
2020-12-10 17:27:54 -08:00
Christoph Hellwig
11129e8ed4
riscv: use memcpy based uaccess for nommu again
This reverts commit adccfb1a80.

Now that the generic uaccess by mempcy code handles unaligned addresses
the generic code can be used for all RISC-V CPUs.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
2020-10-04 10:27:07 -07:00
Linus Torvalds
eab4002660 RISC-V Patches for the 5.7 Merge Window, Part 1
This tag contains the patches I'd like to target for 5.7.  It has a handful of
 new features:
 
 * Partial support for the Kendryte K210.  There are still a few outstanding
   issues that I have patches for, but I don't actually have a board to test
   them so they're not included yet.
 * SBI v0.2 support.
 * Fixes to support for building with LLVM-based toolchains.  The resulting
   images are known not to boot yet.
 
 This builds and boots for me.  There is one merge conflict, it's just a Kconfig
 merge issue.  I can publish a resolved branch if you'd like.
 
 I don't anticipate a part two, but I'll probably have something early in the
 RCs to finish up the K210 support.
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Merge tag 'riscv-for-linus-5.7' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux

Pull RISC-V updates from Palmer Dabbelt:
 "This contains a handful of new features:

   - Partial support for the Kendryte K210.

     There are still a few outstanding issues that I have patches for,
     but I don't actually have a board to test them so they're not
     included yet.

   - SBI v0.2 support.

   - Fixes to support for building with LLVM-based toolchains. The
     resulting images are known not to boot yet.

  I don't anticipate a part two, but I'll probably have something early
  in the RCs to finish up the K210 support"

* tag 'riscv-for-linus-5.7' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: (38 commits)
  riscv: create a loader.bin boot image for Kendryte SoC
  riscv: Kendryte K210 default config
  riscv: Add Kendryte K210 device tree
  riscv: Select required drivers for Kendryte SOC
  riscv: Add Kendryte K210 SoC support
  riscv: Add SOC early init support
  riscv: Unaligned load/store handling for M_MODE
  RISC-V: Support cpu hotplug
  RISC-V: Add supported for ordered booting method using HSM
  RISC-V: Add SBI HSM extension definitions
  RISC-V: Export SBI error to linux error mapping function
  RISC-V: Add cpu_ops and modify default booting method
  RISC-V: Move relocate and few other functions out of __init
  RISC-V: Implement new SBI v0.2 extensions
  RISC-V: Introduce a new config for SBI v0.1
  RISC-V: Add SBI v0.2 extension definitions
  RISC-V: Add basic support for SBI v0.2
  RISC-V: Mark existing SBI as 0.1 SBI.
  riscv: Use macro definition instead of magic number
  riscv: Add support to dump the kernel page tables
  ...
2020-04-09 10:51:30 -07:00
Greentime Hu
adccfb1a80
riscv: uaccess should be used in nommu mode
It might have the unaligned access exception when trying to exchange data
with user space program. In this case, it failed in tty_ioctl(). Therefore
we should enable uaccess.S for NOMMU mode since the generic code doesn't
handle the unaligned access cases.

   0x8013a212 <tty_ioctl+462>:  ld      a5,460(s1)

[    0.115279] Oops - load address misaligned [#1]
[    0.115284] CPU: 0 PID: 29 Comm: sh Not tainted 5.4.0-rc5-00020-gb4c27160d562-dirty #36
[    0.115294] epc: 000000008013a212 ra : 000000008013a212 sp : 000000008f48dd50
[    0.115303]  gp : 00000000801cac28 tp : 000000008fb80000 t0 : 00000000000000e8
[    0.115312]  t1 : 000000008f58f108 t2 : 0000000000000009 s0 : 000000008f48ddf0
[    0.115321]  s1 : 000000008f8c6220 a0 : 0000000000000001 a1 : 000000008f48dd28
[    0.115330]  a2 : 000000008fb80000 a3 : 00000000801a7398 a4 : 0000000000000000
[    0.115339]  a5 : 0000000000000000 a6 : 000000008f58f0c6 a7 : 000000000000001d
[    0.115348]  s2 : 000000008f8c6308 s3 : 000000008f78b7c8 s4 : 000000008fb834c0
[    0.115357]  s5 : 0000000000005413 s6 : 0000000000000000 s7 : 000000008f58f2b0
[    0.115366]  s8 : 000000008f858008 s9 : 000000008f776818 s10: 000000008f776830
[    0.115375]  s11: 000000008fb840a8 t3 : 1999999999999999 t4 : 000000008f78704c
[    0.115384]  t5 : 0000000000000005 t6 : 0000000000000002
[    0.115391] status: 0000000200001880 badaddr: 000000008f8c63ec cause: 0000000000000004
[    0.115401] ---[ end trace 00d490c6a8b6c9ac ]---

This failure could be fixed after this patch applied.

[    0.002282] Run /init as init process
Initializing random number generator... [    0.005573] random: dd: uninitialized urandom read (512 bytes read)
done.

Welcome to Buildroot
buildroot login: root
Password:
Jan  1 00:00:00 login[62]: root login on 'ttySIF0'
~ #

Signed-off-by: Greentime Hu <greentime.hu@sifive.com>
Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
2020-03-18 18:44:30 -07:00
Palmer Dabbelt
abc71bf0a7
RISC-V: Stop using LOCAL for the uaccess fixups
LLVM's integrated assembler doesn't support the LOCAL directive, which we're
using when generating our uaccess fixup tables.  Luckily the table fragment is
small enough that there's only one internal symbol, so using a relative symbol
reference doesn't really complicate anything.

Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
2020-03-03 10:45:14 -08:00
Nick Hu
8ad8b72721
riscv: Add KASAN support
This patch ports the feature Kernel Address SANitizer (KASAN).

Note: The start address of shadow memory is at the beginning of kernel
space, which is 2^64 - (2^39 / 2) in SV39. The size of the kernel space is
2^38 bytes so the size of shadow memory should be 2^38 / 8. Thus, the
shadow memory would not overlap with the fixmap area.

There are currently two limitations in this port,

1. RV64 only: KASAN need large address space for extra shadow memory
region.

2. KASAN can't debug the modules since the modules are allocated in VMALLOC
area. We mapped the shadow memory, which corresponding to VMALLOC area, to
the kasan_early_shadow_page because we don't have enough physical space for
all the shadow memory corresponding to VMALLOC area.

Signed-off-by: Nick Hu <nickhu@andestech.com>
Reported-by: Greentime Hu <green.hu@gmail.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
2020-01-22 13:09:58 -08:00
Olof Johansson
fc585d4a5c riscv: Less inefficient gcc tishift helpers (and export their symbols)
The existing __lshrti3 was really inefficient, and the other two helpers
are also needed to compile some modules.

Add the missing versions, and export all of the symbols like arm64
already does.

This code is based on the assembly generated by libgcc builds.

This fixes a build break triggered by ubsan:

riscv64-unknown-linux-gnu-ld: lib/ubsan.o: in function `.L2':
ubsan.c:(.text.unlikely+0x38): undefined reference to `__ashlti3'
riscv64-unknown-linux-gnu-ld: ubsan.c:(.text.unlikely+0x42): undefined reference to `__ashrti3'

Signed-off-by: Olof Johansson <olof@lixom.net>
[paul.walmsley@sifive.com: use SYM_FUNC_{START,END} instead of
 ENTRY/ENDPROC; note libgcc origin]
Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
2020-01-18 19:13:41 -08:00
Luc Van Oostenryck
4d47ce158e riscv: fix compile failure with EXPORT_SYMBOL() & !MMU
When support for !MMU was added, the declaration of
__asm_copy_to_user() & __asm_copy_from_user() were #ifdefed
out hence their EXPORT_SYMBOL() give an error message like:
  .../riscv_ksyms.c:13:15: error: '__asm_copy_to_user' undeclared here
  .../riscv_ksyms.c:14:15: error: '__asm_copy_from_user' undeclared here

Since these symbols are not defined with !MMU it's wrong to export them.
Same for __clear_user() (even though this one is also declared in
include/asm-generic/uaccess.h and thus doesn't give an error message).

Fix this by doing the EXPORT_SYMBOL() directly where these symbols
are defined: inside lib/uaccess.S itself.

Fixes: 6bd33e1ece ("riscv: fix compile failure with EXPORT_SYMBOL() & !MMU")
Reported-by: kbuild test robot <lkp@intel.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
2019-12-27 21:44:36 -08:00
Christoph Hellwig
6bd33e1ece riscv: add nommu support
The kernel runs in M-mode without using page tables, and thus can't run
bare metal without help from additional firmware.

Most of the patch is just stubbing out code not needed without page
tables, but there is an interesting detail in the signals implementation:

 - The normal RISC-V syscall ABI only implements rt_sigreturn as VDSO
   entry point, but the ELF VDSO is not supported for nommu Linux.
   We instead copy the code to call the syscall onto the stack.

In addition to enabling the nommu code a new defconfig for a small
kernel image that can run in nommu mode on qemu is also provided, to run
a kernel in qemu you can use the following command line:

qemu-system-riscv64 -smp 2 -m 64 -machine virt -nographic \
	-kernel arch/riscv/boot/loader \
	-drive file=rootfs.ext2,format=raw,id=hd0 \
	-device virtio-blk-device,drive=hd0

Contains contributions from Damien Le Moal <Damien.LeMoal@wdc.com>.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Anup Patel <anup@brainfault.org>
[paul.walmsley@sifive.com: updated to apply; add CONFIG_MMU guards
 around PCI_IOBASE definition to fix build issues; fixed checkpatch
 issues; move the PCI_IO_* and VMEMMAP address space macros along
 with the others; resolve sparse warning]
Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
2019-11-17 15:17:39 -08:00
Christoph Hellwig
a4c3733d32 riscv: abstract out CSR names for supervisor vs machine mode
Many of the privileged CSRs exist in a supervisor and machine version
that are used very similarly.  Provide versions of the CSR names and
fields that map to either the S-mode or M-mode variant depending on
a new CONFIG_RISCV_M_MODE kconfig symbol.

Contains contributions from Damien Le Moal <Damien.LeMoal@wdc.com>
and Paul Walmsley <paul.walmsley@sifive.com>.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de> # for drivers/clocksource, drivers/irqchip
[paul.walmsley@sifive.com: updated to apply]
Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
2019-11-05 09:20:42 -08:00
Bin Meng
4f3f900846 riscv: Using CSR numbers to access CSRs
Since commit a3182c91ef ("RISC-V: Access CSRs using CSR numbers"),
we should prefer accessing CSRs using their CSR numbers, but there
are several leftovers like sstatus / sptbr we missed.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
2019-08-30 11:04:19 -07:00
Palmer Dabbelt
81a48ee417 RISC-V: Remove udivdi3
This should never have landed in the first place: it was added as part
of 64-bit divide support for 32-bit systems, but the kernel doesn't
allow this sort of division.  I must have forgotten to remove it.

This patch removes the support.  Since this routine only worked on
64-bit platforms but was only built on 32-bit platforms, it's
essentially just nonsense anyway.

Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
Acked-by: Nicolas Pitre <nico@fluxnic.net>
Link: https://lore.kernel.org/linux-riscv/nycvar.YSQ.7.76.1908061413360.19480@knanqh.ubzr/T/#t
Reported-by: Eric Lin <tesheng@andestech.com>
Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
2019-08-08 16:05:38 -07:00
Paul Walmsley
66cc016ab7 riscv: delay: use do_div() instead of __udivdi3()
In preparation for removing __udivdi3() from the RISC-V
architecture-specific files, convert its one user to use do_div().
This avoids breaking the RV32 build after __udivdi3() is removed.

This second version removes the assignment of the remainder to an
unused temporary variable.  Thanks to Nicolas Pitre <nico@fluxnic.net>
for the suggestion.

Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Nicolas Pitre <nico@fluxnic.net>
2019-08-08 16:05:38 -07:00
Linus Torvalds
eb7c825bf7 RISC-V patches for v5.2-rc6
This tag contains fixes, defconfig, and DT data changes for the v5.2-rc
 series.  The fixes are relatively straightforward:
 
 - Addition of a TLB fence in the vmalloc_fault path, so the CPU doesn't
   enter an infinite page fault loop;
 - Readdition of the pm_power_off export, so device drivers that
   reassign it can now be built as modules;
 - A udelay() fix for RV32, fixing a miscomputation of the delay time;
 - Removal of deprecated smp_mb__*() barriers.
 
 The tag also adds initial DT data infrastructure for arch/riscv, along
 with initial data for the SiFive FU540-C000 SoC and the corresponding
 HiFive Unleashed board.
 
 We also update the RV64 defconfig to include some core drivers for the
 FU540 in the build.
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Merge tag 'riscv-for-v5.2/fixes-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux

Pull RISC-V fixes from Paul Walmsley:
 "This contains fixes, defconfig, and DT data changes for the v5.2-rc
  series.

  The fixes are relatively straightforward:

   - Addition of a TLB fence in the vmalloc_fault path, so the CPU
     doesn't enter an infinite page fault loop

   - Readdition of the pm_power_off export, so device drivers that
     reassign it can now be built as modules

   - A udelay() fix for RV32, fixing a miscomputation of the delay time

   - Removal of deprecated smp_mb__*() barriers

  This also adds initial DT data infrastructure for arch/riscv, along
  with initial data for the SiFive FU540-C000 SoC and the corresponding
  HiFive Unleashed board.

  We also update the RV64 defconfig to include some core drivers for the
  FU540 in the build"

* tag 'riscv-for-v5.2/fixes-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux:
  riscv: remove unused barrier defines
  riscv: mm: synchronize MMU after pte change
  riscv: dts: add initial board data for the SiFive HiFive Unleashed
  riscv: dts: add initial support for the SiFive FU540-C000 SoC
  dt-bindings: riscv: convert cpu binding to json-schema
  dt-bindings: riscv: sifive: add YAML documentation for the SiFive FU540
  arch: riscv: add support for building DTB files from DT source data
  riscv: Fix udelay in RV32.
  riscv: export pm_power_off again
  RISC-V: defconfig: enable clocks, serial console
2019-06-17 10:34:03 -07:00
Nick Hu
d0e1f2110a riscv: Fix udelay in RV32.
In RV32, udelay would delay the wrong cycle. When it shifts right
"UDELAY_SHIFT" bits, it either delays 0 cycle or 1 cycle. It only works
correctly in RV64. Because the 'ucycles' always needs to be 64 bits
variable.

Signed-off-by: Nick Hu <nickhu@andestech.com>
Reviewed-by: Palmer Dabbelt <palmer@sifive.com>
[paul.walmsley@sifive.com: fixed minor spelling error]
Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
2019-06-11 08:04:26 -07:00
Thomas Gleixner
50acfb2b76 treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 286
Based on 1 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license as published by
  the free software foundation version 2 this program is distributed
  in the hope that it will be useful but without any warranty without
  even the implied warranty of merchantability or fitness for a
  particular purpose see the gnu general public license for more
  details

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 97 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190529141901.025053186@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-06-05 17:36:37 +02:00
Thomas Gleixner
ec8f24b7fa treewide: Add SPDX license identifier - Makefile/Kconfig
Add SPDX license identifiers to all Make/Kconfig files which:

 - Have no license information of any form

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

  GPL-2.0-only

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-21 10:50:46 +02:00
Olof Johansson
a266cdba17
RISC-V: lib: minor asm cleanup
Fix tab/space conversion and use ENTRY/ENDPROC macros.

Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
2018-12-21 08:17:02 -08:00
Olof Johansson
85d90b9180
RISC-V: lib: Fix build error for 64-bit
Fixes the following build error from tinyconfig:

riscv64-unknown-linux-gnu-ld: kernel/sched/fair.o: in function `.L8':
fair.c:(.text+0x70): undefined reference to `__lshrti3'
riscv64-unknown-linux-gnu-ld: kernel/time/clocksource.o: in function `.L0 ':
clocksource.c:(.text+0x334): undefined reference to `__lshrti3'

Fixes: 7f47c73b35 ("RISC-V: Build tishift only on 64-bit")
Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
2018-11-12 18:09:55 -08:00