Since commit 85e031154c ("powerpc/bpf: Perform complete extra passes
to update addresses"), two additional passes are performed to avoid
space and CPU time wastage on powerpc. But these extra passes led to
WARN_ON_ONCE() hits in bpf_add_extable_entry() as extable entries are
populated again, during the extra pass, without resetting the index.
Fix it by resetting entry index before repopulating extable entries,
if and when there is an additional pass.
Fixes: 85e031154c ("powerpc/bpf: Perform complete extra passes to update addresses")
Cc: stable@vger.kernel.org # v6.3+
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Reviewed-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230425065829.18189-1-hbathini@linux.ibm.com
PC-Relative or PCREL addressing is an extension to the ELF ABI which
uses Power ISA v3.1 PC-relative instructions to calculate addresses,
rather than the traditional TOC scheme.
Add an option to build vmlinux using pcrel addressing. Modules continue
to use TOC addressing.
- TOC address helpers and r2 are poisoned with -1 when running vmlinux.
r2 could be used for something useful once things are ironed out.
- Assembly must call C functions with @notoc annotation, or the linker
complains aobut a missing nop after the call. This is done with the
CFUNC macro introduced earlier.
- Boot: with the exception of prom_init, the execution branches to the
kernel virtual address early in boot, before any addresses are
generated, which ensures 34-bit pcrel addressing does not miss the
high PAGE_OFFSET bits. TOC relative addressing has a similar
requirement. prom_init does not go to the virtual address and its
addresses should not carry over to the post-prom kernel.
- Ftrace trampolines are converted from TOC addressing to pcrel
addressing, including module ftrace trampolines that currently use the
kernel TOC to find ftrace target functions.
- BPF function prologue and function calling generation are converted
from TOC to pcrel.
- copypage_64.S has an interesting problem, prefixed instructions have
alignment restrictions so the linker can add padding, which makes the
assembler treat the difference between two local labels as
non-constant even if alignment is arranged so padding is not required.
This may need toolchain help to solve nicely, for now move the prefix
instruction out of the alternate patch section to work around it.
This reduces kernel text size by about 6%.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230408021752.862660-6-npiggin@gmail.com
When an ALU instruction is preceded by a MOV instruction
that just moves a source register into the destination register of
the ALU, replace that MOV+ALU instructions by an ALU operation
taking the source of the MOV as second source instead of using its
destination.
Before the change, code could look like the following, with
superfluous separate register move (mr) instructions.
70: 7f c6 f3 78 mr r6,r30
74: 7f a5 eb 78 mr r5,r29
78: 30 c6 ff f4 addic r6,r6,-12
7c: 7c a5 01 d4 addme r5,r5
With this commit, addition instructions take r30 and r29 directly.
70: 30 de ff f4 addic r6,r30,-12
74: 7c bd 01 d4 addme r5,r29
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/b6719beaf01f9dcbcdbb787ef67c4a2f8e3a4cb6.1675245773.git.christophe.leroy@csgroup.eu
At the time being, all ALU operation are performed with same L-source
and destination, requiring the L-source to be moved into destination via
a separate register move, like:
70: 7f c6 f3 78 mr r6,r30
74: 7f a5 eb 78 mr r5,r29
78: 30 c6 ff f4 addic r6,r6,-12
7c: 7c a5 01 d4 addme r5,r5
Introduce a second source register to all ALU operations. For the time
being that second source register is made equal to the destination
register.
That change will allow, via following patch, to optimise the generated
code as:
70: 30 de ff f4 addic r6,r30,-12
74: 7c bd 01 d4 addme r5,r29
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/d5aaaba50d9d6b4a0e9f0cd4a5e34101aca1e247.1675245773.git.christophe.leroy@csgroup.eu
Now that two real additional passes are performed in case of extra pass
requested by BPF core, padding is not needed anymore except during
initial pass done before memory allocation to count maximum possible
program size.
So, only do the padding when 'image' is NULL.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/921851d6577badc1e6b08b270a0ced80a6a26d03.1675245773.git.christophe.leroy@csgroup.eu
BPF core calls the jit compiler again for an extra pass in order
to properly set subprog addresses.
Unlike other architectures, powerpc only updates the addresses
during that extra pass. It means that holes must have been left
in the code in order to enable the maximum possible instruction
size.
In order to avoid waste of space, and waste of CPU time on powerpc
processors on which the NOP instruction is not 0-cycle, perform
two real additional passes.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/d484a4ac95949ff55fc4344b674e7c0d3ddbfcd5.1675245773.git.christophe.leroy@csgroup.eu
BPF progs are never called with more than one argument, plus the
tail call count as a second argument when needed.
So, no need to retrieve 9th and 10th argument (5th 64 bits argument)
from the stack in prologue.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/89a200fb45048601475c092c5775294dee3886de.1675245773.git.christophe.leroy@csgroup.eu
Until now a stack frame was set at all time due to the need
to keep tail call counter in the stack.
But since commit 89d21e259a ("powerpc/bpf/32: Fix Oops on tail call
tests") the tail call counter is passed via register r4. It is therefore
not necessary anymore to have a stack frame for that.
Just like PPC64, implement bpf_has_stack_frame() and only sets the frame
when needed.
The difference with PPC64 is that PPC32 doesn't have a redzone, so
the stack is required as soon as non volatile registers are used or
when tail call count is set up.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
[mpe: Fix commit reference in change log]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/62d7b654a3cfe73d998697cb29bbc5ffd89bfdb1.1675245773.git.christophe.leroy@csgroup.eu
test_bpf tail call tests end up as:
test_bpf: #0 Tail call leaf jited:1 85 PASS
test_bpf: #1 Tail call 2 jited:1 111 PASS
test_bpf: #2 Tail call 3 jited:1 145 PASS
test_bpf: #3 Tail call 4 jited:1 170 PASS
test_bpf: #4 Tail call load/store leaf jited:1 190 PASS
test_bpf: #5 Tail call load/store jited:1
BUG: Unable to handle kernel data access on write at 0xf1b4e000
Faulting instruction address: 0xbe86b710
Oops: Kernel access of bad area, sig: 11 [#1]
BE PAGE_SIZE=4K MMU=Hash PowerMac
Modules linked in: test_bpf(+)
CPU: 0 PID: 97 Comm: insmod Not tainted 6.1.0-rc4+ #195
Hardware name: PowerMac3,1 750CL 0x87210 PowerMac
NIP: be86b710 LR: be857e88 CTR: be86b704
REGS: f1b4df20 TRAP: 0300 Not tainted (6.1.0-rc4+)
MSR: 00009032 <EE,ME,IR,DR,RI> CR: 28008242 XER: 00000000
DAR: f1b4e000 DSISR: 42000000
GPR00: 00000001 f1b4dfe0 c11d2280 00000000 00000000 00000000 00000002 00000000
GPR08: f1b4e000 be86b704 f1b4e000 00000000 00000000 100d816a f2440000 fe73baa8
GPR16: f2458000 00000000 c1941ae4 f1fe2248 00000045 c0de0000 f2458030 00000000
GPR24: 000003e8 0000000f f2458000 f1b4dc90 3e584b46 00000000 f24466a0 c1941a00
NIP [be86b710] 0xbe86b710
LR [be857e88] __run_one+0xec/0x264 [test_bpf]
Call Trace:
[f1b4dfe0] [00000002] 0x2 (unreliable)
Instruction dump:
XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX
XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX
---[ end trace 0000000000000000 ]---
This is a tentative to write above the stack. The problem is encoutered
with tests added by commit 38608ee7b6 ("bpf, tests: Add load store
test case for tail call")
This happens because tail call is done to a BPF prog with a different
stack_depth. At the time being, the stack is kept as is when the caller
tail calls its callee. But at exit, the callee restores the stack based
on its own properties. Therefore here, at each run, r1 is erroneously
increased by 32 - 16 = 16 bytes.
This was done that way in order to pass the tail call count from caller
to callee through the stack. As powerpc32 doesn't have a red zone in
the stack, it was necessary the maintain the stack as is for the tail
call. But it was not anticipated that the BPF frame size could be
different.
Let's take a new approach. Use register r4 to carry the tail call count
during the tail call, and save it into the stack at function entry if
required. This means the input parameter must be in r3, which is more
correct as it is a 32 bits parameter, then tail call better match with
normal BPF function entry, the down side being that we move that input
parameter back and forth between r3 and r4. That can be optimised later.
Doing that also has the advantage of maximising the common parts between
tail calls and a normal function exit.
With the fix, tail call tests are now successfull:
test_bpf: #0 Tail call leaf jited:1 53 PASS
test_bpf: #1 Tail call 2 jited:1 115 PASS
test_bpf: #2 Tail call 3 jited:1 154 PASS
test_bpf: #3 Tail call 4 jited:1 165 PASS
test_bpf: #4 Tail call load/store leaf jited:1 101 PASS
test_bpf: #5 Tail call load/store jited:1 141 PASS
test_bpf: #6 Tail call error path, max count reached jited:1 994 PASS
test_bpf: #7 Tail call count preserved across function calls jited:1 140975 PASS
test_bpf: #8 Tail call error path, NULL target jited:1 110 PASS
test_bpf: #9 Tail call error path, index out of range jited:1 69 PASS
test_bpf: test_tail_calls: Summary: 10 PASSED, 0 FAILED, [10/10 JIT'ed]
Suggested-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Fixes: 51c66ad849 ("powerpc/bpf: Implement extended BPF on PPC32")
Cc: stable@vger.kernel.org
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Tested-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/757acccb7fbfc78efa42dcf3c974b46678198905.1669278887.git.christophe.leroy@csgroup.eu
This adds two atomic opcodes BPF_XCHG and BPF_CMPXCHG on ppc32, both
of which include the BPF_FETCH flag. The kernel's atomic_cmpxchg
operation fundamentally has 3 operands, but we only have two register
fields. Therefore the operand we compare against (the kernel's API
calls it 'old') is hard-coded to be BPF_REG_R0. Also, kernel's
atomic_cmpxchg returns the previous value at dst_reg + off. JIT the
same for BPF too with return value put in BPF_REG_0.
BPF_REG_R0 = atomic_cmpxchg(dst_reg + off, BPF_REG_R0, src_reg);
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Tested-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> (ppc64le)
Reviewed-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220610155552.25892-6-hbathini@linux.ibm.com
This adds two atomic opcodes BPF_XCHG and BPF_CMPXCHG on ppc64, both
of which include the BPF_FETCH flag. The kernel's atomic_cmpxchg
operation fundamentally has 3 operands, but we only have two register
fields. Therefore the operand we compare against (the kernel's API
calls it 'old') is hard-coded to be BPF_REG_R0. Also, kernel's
atomic_cmpxchg returns the previous value at dst_reg + off. JIT the
same for BPF too with return value put in BPF_REG_0.
BPF_REG_R0 = atomic_cmpxchg(dst_reg + off, BPF_REG_R0, src_reg);
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Tested-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> (ppc64le)
Reviewed-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220610155552.25892-4-hbathini@linux.ibm.com
Adding instructions for ppc64 for
atomic[64]_fetch_add
atomic[64]_fetch_and
atomic[64]_fetch_or
atomic[64]_fetch_xor
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Tested-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> (ppc64le)
Reviewed-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220610155552.25892-3-hbathini@linux.ibm.com
Adding instructions for ppc64 for
atomic[64]_and
atomic[64]_or
atomic[64]_xor
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Tested-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> (ppc64le)
Reviewed-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220610155552.25892-2-hbathini@linux.ibm.com
- Enforce kernel RO, and implement STRICT_MODULE_RWX for 603.
- Add support for livepatch to 32-bit.
- Implement CONFIG_DYNAMIC_FTRACE_WITH_ARGS.
- Merge vdso64 and vdso32 into a single directory.
- Fix build errors with newer binutils.
- Add support for UADDR64 relocations, which are emitted by some toolchains. This allows
powerpc to build with the latest lld.
- Fix (another) potential userspace r13 corruption in transactional memory handling.
- Cleanups of function descriptor handling & related fixes to LKDTM.
Thanks to: Abdul Haleem, Alexey Kardashevskiy, Anders Roxell, Aneesh Kumar K.V, Anton
Blanchard, Arnd Bergmann, Athira Rajeev, Bhaskar Chowdhury, Cédric Le Goater, Chen
Jingwen, Christophe JAILLET, Christophe Leroy, Corentin Labbe, Daniel Axtens, Daniel
Henrique Barboza, David Dai, Fabiano Rosas, Ganesh Goudar, Guo Zhengkui, Hangyu Hua, Haren
Myneni, Hari Bathini, Igor Zhbanov, Jakob Koschel, Jason Wang, Jeremy Kerr, Joachim
Wiberg, Jordan Niethe, Julia Lawall, Kajol Jain, Kees Cook, Laurent Dufour, Madhavan
Srinivasan, Mamatha Inamdar, Maxime Bizon, Maxim Kiselev, Maxim Kochetkov, Michal
Suchanek, Nageswara R Sastry, Nathan Lynch, Naveen N. Rao, Nicholas Piggin, Nour-eddine
Taleb, Paul Menzel, Ping Fang, Pratik R. Sampat, Randy Dunlap, Ritesh Harjani, Rohan
McLure, Russell Currey, Sachin Sant, Segher Boessenkool, Shivaprasad G Bhat, Sourabh Jain,
Thierry Reding, Tobias Waldekranz, Tyrel Datwyler, Vaibhav Jain, Vladimir Oltean, Wedson
Almeida Filho, YueHaibing.
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Merge tag 'powerpc-5.18-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux
Pull powerpc updates from Michael Ellerman:
"Livepatch support for 32-bit is probably the standout new feature,
otherwise mostly just lots of bits and pieces all over the board.
There's a series of commits cleaning up function descriptor handling,
which touches a few other arches as well as LKDTM. It has acks from
Arnd, Kees and Helge.
Summary:
- Enforce kernel RO, and implement STRICT_MODULE_RWX for 603.
- Add support for livepatch to 32-bit.
- Implement CONFIG_DYNAMIC_FTRACE_WITH_ARGS.
- Merge vdso64 and vdso32 into a single directory.
- Fix build errors with newer binutils.
- Add support for UADDR64 relocations, which are emitted by some
toolchains. This allows powerpc to build with the latest lld.
- Fix (another) potential userspace r13 corruption in transactional
memory handling.
- Cleanups of function descriptor handling & related fixes to LKDTM.
Thanks to Abdul Haleem, Alexey Kardashevskiy, Anders Roxell, Aneesh
Kumar K.V, Anton Blanchard, Arnd Bergmann, Athira Rajeev, Bhaskar
Chowdhury, Cédric Le Goater, Chen Jingwen, Christophe JAILLET,
Christophe Leroy, Corentin Labbe, Daniel Axtens, Daniel Henrique
Barboza, David Dai, Fabiano Rosas, Ganesh Goudar, Guo Zhengkui, Hangyu
Hua, Haren Myneni, Hari Bathini, Igor Zhbanov, Jakob Koschel, Jason
Wang, Jeremy Kerr, Joachim Wiberg, Jordan Niethe, Julia Lawall, Kajol
Jain, Kees Cook, Laurent Dufour, Madhavan Srinivasan, Mamatha Inamdar,
Maxime Bizon, Maxim Kiselev, Maxim Kochetkov, Michal Suchanek,
Nageswara R Sastry, Nathan Lynch, Naveen N. Rao, Nicholas Piggin,
Nour-eddine Taleb, Paul Menzel, Ping Fang, Pratik R. Sampat, Randy
Dunlap, Ritesh Harjani, Rohan McLure, Russell Currey, Sachin Sant,
Segher Boessenkool, Shivaprasad G Bhat, Sourabh Jain, Thierry Reding,
Tobias Waldekranz, Tyrel Datwyler, Vaibhav Jain, Vladimir Oltean,
Wedson Almeida Filho, and YueHaibing"
* tag 'powerpc-5.18-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (179 commits)
powerpc/pseries: Fix use after free in remove_phb_dynamic()
powerpc/time: improve decrementer clockevent processing
powerpc/time: Fix KVM host re-arming a timer beyond decrementer range
powerpc/tm: Fix more userspace r13 corruption
powerpc/xive: fix return value of __setup handler
powerpc/64: Add UADDR64 relocation support
powerpc: 8xx: fix a return value error in mpc8xx_pic_init
powerpc/ps3: remove unneeded semicolons
powerpc/64: Force inlining of prevent_user_access() and set_kuap()
powerpc/bitops: Force inlining of fls()
powerpc: declare unmodified attribute_group usages const
powerpc/spufs: Fix build warning when CONFIG_PROC_FS=n
powerpc/secvar: fix refcount leak in format_show()
powerpc/64e: Tie PPC_BOOK3E_64 to PPC_FSL_BOOK3E
powerpc: Move C prototypes out of asm-prototypes.h
powerpc/kexec: Declare kexec_paca static
powerpc/smp: Declare current_set static
powerpc: Cleanup asm-prototypes.c
powerpc/ftrace: Use STK_GOT in ftrace_mprofile.S
powerpc/ftrace: Regroup PPC64 specific operations in ftrace_mprofile.S
...
In bpf_jit_build_body(), the mapping of TMP_REG_1 and TMP_REG_2's bpf
register to ppc register is evalulated at every use despite not
changing. Instead, determine the ppc register once and store the result.
Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
[Rebased, converted additional usage sites]
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/0944e2f0fa6dd254ea401f1c946fb6c9a5294278.1644834730.git.naveen.n.rao@linux.vnet.ibm.com
When calling BPF helpers, we load the function address to call into a
register. This can result in upto 5 instructions. Optimize this by
instead using the kernel toc in r2 and adjusting offset to the BPF
helper. This works since all BPF helpers are part of kernel text, and
all BPF programs/functions utilize the kernel TOC.
Further more:
- load the actual function entry address in elf v1, rather than loading
it through the function descriptor address.
- load the Local Entry Point (LEP) in elf v2 skipping TOC setup.
- consolidate code across elf abi v1 and v2 by using r12 on both.
Reported-by: Anton Blanchard <anton@ozlabs.org>
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1233c7544e60dcb021c52b1f840b0f21a87b33ed.1644834730.git.naveen.n.rao@linux.vnet.ibm.com
BPF helpers always reside in core kernel and all BPF programs use the
kernel TOC. As such, there is no need to load the TOC before calling
helpers or other BPF functions. Drop code to do the same.
Add a check to ensure we don't proceed if this assumption ever changes
in future.
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/a3cd3da4d24d95d845cd10382b1af083600c9074.1644834730.git.naveen.n.rao@linux.vnet.ibm.com
In preparation for using kernel TOC, load the same in r2 on entry. With
elfv1, the kernel TOC is already setup by our caller.
We adjust the number of instructions to skip on a tail call accordingly.
We get rid of the #ifdef in bpf_jit_emit_tail_call() since
FUNCTION_DESCR_SIZE is itself under a #ifdef.
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/18a05a4ceec14a8617c9dd4b7128d0afa83fd14e.1644834730.git.naveen.n.rao@linux.vnet.ibm.com
In preparation for preserving kernel toc in r2, switch BPF_REG_AX from
r2 to r12. r12 is not used by bpf JIT except during external helper/bpf
calls, or with BPF_NOSPEC. These sequences aren't emitted when
BPF_REG_AX is used for constant blinding and other purposes.
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/e109f98617eacb4512c17a48525e94eda42889e6.1644834730.git.naveen.n.rao@linux.vnet.ibm.com
In some scenarios, it is possible that the program epilogue is outside
the branch range for a BPF_EXIT instruction. Instead of rejecting such
programs, emit epilogue as an alternate exit point from the program.
Track the location of the same so that subsequent exits can take either
of the two paths.
Reported-by: Jordan Niethe <jniethe5@gmail.com>
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/33aa2e92645a92712be23b18035a2c6dcb92ff8d.1644834730.git.naveen.n.rao@linux.vnet.ibm.com
PPC_BCC() emits two instructions to accommodate scenarios where we need
to branch outside the range of a conditional branch. PPC_BCC_SHORT()
emits a single branch instruction and can be used when the branch is
known to be within a conditional branch range.
Convert some of the uses of PPC_BCC() in the powerpc BPF JIT over to
PPC_BCC_SHORT() where we know the branch range.
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/edbca01377d1d5f472868bf6d8962b0a0d85b96f.1644834730.git.naveen.n.rao@linux.vnet.ibm.com
During the first pass, addrs[] is still being populated. So, all
branches to following instructions will appear to be going to the start
of the JIT program. Ignore branch range validation for such instructions
and assume those to be in range. Branch range validation will happen
during the second pass after addrs[] is setup properly.
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/bc517413d11636e20dbfc88503dad14bcbe391e2.1644834730.git.naveen.n.rao@linux.vnet.ibm.com
BPF_REG_5, BPF_REG_AX and TMP_REG are mapped on non volatile registers
because there are not enough volatile registers, but they don't need
to be preserved on function calls.
So when some volatile registers become available, those registers can
always be reallocated regardless of whether SEEN_FUNC is set or not.
Suggested-by: Naveen N. Rao <naveen.n.rao@linux.ibm.com>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/b04c246874b716911139c04bc004b3b14eed07ef.1641817763.git.christophe.leroy@csgroup.eu
Daniel Borkmann says:
====================
pull-request: bpf-next 2022-02-09
We've added 126 non-merge commits during the last 16 day(s) which contain
a total of 201 files changed, 4049 insertions(+), 2215 deletions(-).
The main changes are:
1) Add custom BPF allocator for JITs that pack multiple programs into a huge
page to reduce iTLB pressure, from Song Liu.
2) Add __user tagging support in vmlinux BTF and utilize it from BPF
verifier when generating loads, from Yonghong Song.
3) Add per-socket fast path check guarding from cgroup/BPF overhead when
used by only some sockets, from Pavel Begunkov.
4) Continued libbpf deprecation work of APIs/features and removal of their
usage from samples, selftests, libbpf & bpftool, from Andrii Nakryiko
and various others.
5) Improve BPF instruction set documentation by adding byte swap
instructions and cleaning up load/store section, from Christoph Hellwig.
6) Switch BPF preload infra to light skeleton and remove libbpf dependency
from it, from Alexei Starovoitov.
7) Fix architecture-agnostic macros in libbpf for accessing syscall
arguments from BPF progs for non-x86 architectures,
from Ilya Leoshkevich.
8) Rework port members in struct bpf_sk_lookup and struct bpf_sock to be
of 16-bit field with anonymous zero padding, from Jakub Sitnicki.
9) Add new bpf_copy_from_user_task() helper to read memory from a different
task than current. Add ability to create sleepable BPF iterator progs,
from Kenny Yu.
10) Implement XSK batching for ice's zero-copy driver used by AF_XDP and
utilize TX batching API from XSK buffer pool, from Maciej Fijalkowski.
11) Generate temporary netns names for BPF selftests to avoid naming
collisions, from Hangbin Liu.
12) Implement bpf_core_types_are_compat() with limited recursion for
in-kernel usage, from Matteo Croce.
13) Simplify pahole version detection and finally enable CONFIG_DEBUG_INFO_DWARF5
to be selected with CONFIG_DEBUG_INFO_BTF, from Nathan Chancellor.
14) Misc minor fixes to libbpf and selftests from various folks.
* https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (126 commits)
selftests/bpf: Cover 4-byte load from remote_port in bpf_sk_lookup
bpf: Make remote_port field in struct bpf_sk_lookup 16-bit wide
libbpf: Fix compilation warning due to mismatched printf format
selftests/bpf: Test BPF_KPROBE_SYSCALL macro
libbpf: Add BPF_KPROBE_SYSCALL macro
libbpf: Fix accessing the first syscall argument on s390
libbpf: Fix accessing the first syscall argument on arm64
libbpf: Allow overriding PT_REGS_PARM1{_CORE}_SYSCALL
selftests/bpf: Skip test_bpf_syscall_macro's syscall_arg1 on arm64 and s390
libbpf: Fix accessing syscall arguments on riscv
libbpf: Fix riscv register names
libbpf: Fix accessing syscall arguments on powerpc
selftests/bpf: Use PT_REGS_SYSCALL_REGS in bpf_syscall_macro
libbpf: Add PT_REGS_SYSCALL_REGS macro
selftests/bpf: Fix an endianness issue in bpf_syscall_macro test
bpf: Fix bpf_prog_pack build HPAGE_PMD_SIZE
bpf: Fix leftover header->pages in sparc and powerpc code.
libbpf: Fix signedness bug in btf_dump_array_data()
selftests/bpf: Do not export subtest as standalone test
bpf, x86_64: Fail gracefully on bpf_jit_binary_pack_finalize failures
...
====================
Link: https://lore.kernel.org/r/20220209210050.8425-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Replace header->pages * PAGE_SIZE with new header->size.
Fixes: ed2d9e1a26 ("bpf: Use size instead of pages in bpf_binary_header")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Song Liu <song@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220208220509.4180389-2-song@kernel.org
Johan reported the below crash with test_bpf on ppc64 e5500:
test_bpf: #296 ALU_END_FROM_LE 64: 0x0123456789abcdef -> 0x67452301 jited:1
Oops: Exception in kernel mode, sig: 4 [#1]
BE PAGE_SIZE=4K SMP NR_CPUS=24 QEMU e500
Modules linked in: test_bpf(+)
CPU: 0 PID: 76 Comm: insmod Not tainted 5.14.0-03771-g98c2059e008a-dirty #1
NIP: 8000000000061c3c LR: 80000000006dea64 CTR: 8000000000061c18
REGS: c0000000032d3420 TRAP: 0700 Not tainted (5.14.0-03771-g98c2059e008a-dirty)
MSR: 0000000080089000 <EE,ME> CR: 88002822 XER: 20000000 IRQMASK: 0
<...>
NIP [8000000000061c3c] 0x8000000000061c3c
LR [80000000006dea64] .__run_one+0x104/0x17c [test_bpf]
Call Trace:
.__run_one+0x60/0x17c [test_bpf] (unreliable)
.test_bpf_init+0x6a8/0xdc8 [test_bpf]
.do_one_initcall+0x6c/0x28c
.do_init_module+0x68/0x28c
.load_module+0x2460/0x2abc
.__do_sys_init_module+0x120/0x18c
.system_call_exception+0x110/0x1b8
system_call_common+0xf0/0x210
--- interrupt: c00 at 0x101d0acc
<...>
---[ end trace 47b2bf19090bb3d0 ]---
Illegal instruction
The illegal instruction turned out to be 'ldbrx' emitted for
BPF_FROM_[L|B]E, which was only introduced in ISA v2.06. Guard use of
the same and implement an alternative approach for older processors.
Fixes: 156d0e290e ("powerpc/ebpf/jit: Implement JIT compiler for extended BPF")
Reported-by: Johan Almbladh <johan.almbladh@anyfinetworks.com>
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Tested-by: Johan Almbladh <johan.almbladh@anyfinetworks.com>
Acked-by: Johan Almbladh <johan.almbladh@anyfinetworks.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/d1e51c6fdf572062cf3009a751c3406bda01b832.1641468127.git.naveen.n.rao@linux.vnet.ibm.com
Pad instructions emitted for BPF_CALL so that the number of instructions
generated does not change for different function addresses. This is
especially important for calls to other bpf functions, whose address
will only be known during extra pass.
Fixes: 51c66ad849 ("powerpc/bpf: Implement extended BPF on PPC32")
Cc: stable@vger.kernel.org # v5.13+
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/52d8fe51f7620a6f27f377791564d79d75463576.1641468127.git.naveen.n.rao@linux.vnet.ibm.com
- Optimise radix KVM guest entry/exit by 2x on Power9/Power10.
- Allow firmware to tell us whether to disable the entry and uaccess flushes on Power10
or later CPUs.
- Add BPF_PROBE_MEM support for 32 and 64-bit BPF jits.
- Several fixes and improvements to our hard lockup watchdog.
- Activate HAVE_DYNAMIC_FTRACE_WITH_REGS on 32-bit.
- Allow building the 64-bit Book3S kernel without hash MMU support, ie. Radix only.
- Add KUAP (SMAP) support for 40x, 44x, 8xx, Book3E (64-bit).
- Add new encodings for perf_mem_data_src.mem_hops field, and use them on Power10.
- A series of small performance improvements to 64-bit interrupt entry.
- Several commits fixing issues when building with the clang integrated assembler.
- Many other small features and fixes.
Thanks to: Alan Modra, Alexey Kardashevskiy, Ammar Faizi, Anders Roxell, Arnd Bergmann,
Athira Rajeev, Cédric Le Goater, Christophe JAILLET, Christophe Leroy, Christoph Hellwig,
Daniel Axtens, David Yang, Erhard Furtner, Fabiano Rosas, Greg Kroah-Hartman, Guo Ren,
Hari Bathini, Jason Wang, Joel Stanley, Julia Lawall, Kajol Jain, Kees Cook, Laurent
Dufour, Madhavan Srinivasan, Mark Brown, Minghao Chi, Nageswara R Sastry, Naresh Kamboju,
Nathan Chancellor, Nathan Lynch, Nicholas Piggin, Nick Child, Oliver O'Halloran, Peiwei
Hu, Randy Dunlap, Ravi Bangoria, Rob Herring, Russell Currey, Sachin Sant, Sean
Christopherson, Segher Boessenkool, Thadeu Lima de Souza Cascardo, Tyrel Datwyler, Xiang
wangx, Yang Guang.
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Merge tag 'powerpc-5.17-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux
Pull powerpc updates from Michael Ellerman:
- Optimise radix KVM guest entry/exit by 2x on Power9/Power10.
- Allow firmware to tell us whether to disable the entry and uaccess
flushes on Power10 or later CPUs.
- Add BPF_PROBE_MEM support for 32 and 64-bit BPF jits.
- Several fixes and improvements to our hard lockup watchdog.
- Activate HAVE_DYNAMIC_FTRACE_WITH_REGS on 32-bit.
- Allow building the 64-bit Book3S kernel without hash MMU support, ie.
Radix only.
- Add KUAP (SMAP) support for 40x, 44x, 8xx, Book3E (64-bit).
- Add new encodings for perf_mem_data_src.mem_hops field, and use them
on Power10.
- A series of small performance improvements to 64-bit interrupt entry.
- Several commits fixing issues when building with the clang integrated
assembler.
- Many other small features and fixes.
Thanks to Alan Modra, Alexey Kardashevskiy, Ammar Faizi, Anders Roxell,
Arnd Bergmann, Athira Rajeev, Cédric Le Goater, Christophe JAILLET,
Christophe Leroy, Christoph Hellwig, Daniel Axtens, David Yang, Erhard
Furtner, Fabiano Rosas, Greg Kroah-Hartman, Guo Ren, Hari Bathini, Jason
Wang, Joel Stanley, Julia Lawall, Kajol Jain, Kees Cook, Laurent Dufour,
Madhavan Srinivasan, Mark Brown, Minghao Chi, Nageswara R Sastry, Naresh
Kamboju, Nathan Chancellor, Nathan Lynch, Nicholas Piggin, Nick Child,
Oliver O'Halloran, Peiwei Hu, Randy Dunlap, Ravi Bangoria, Rob Herring,
Russell Currey, Sachin Sant, Sean Christopherson, Segher Boessenkool,
Thadeu Lima de Souza Cascardo, Tyrel Datwyler, Xiang wangx, and Yang
Guang.
* tag 'powerpc-5.17-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (240 commits)
powerpc/xmon: Dump XIVE information for online-only processors.
powerpc/opal: use default_groups in kobj_type
powerpc/cacheinfo: use default_groups in kobj_type
powerpc/sched: Remove unused TASK_SIZE_OF
powerpc/xive: Add missing null check after calling kmalloc
powerpc/floppy: Remove usage of the deprecated "pci-dma-compat.h" API
selftests/powerpc: Add a test of sigreturning to an unaligned address
powerpc/64s: Use EMIT_WARN_ENTRY for SRR debug warnings
powerpc/64s: Mask NIP before checking against SRR0
powerpc/perf: Fix spelling of "its"
powerpc/32: Fix boot failure with GCC latent entropy plugin
powerpc/code-patching: Replace patch_instruction() by ppc_inst_write() in selftests
powerpc/code-patching: Move code patching selftests in its own file
powerpc/code-patching: Move instr_is_branch_{i/b}form() in code-patching.h
powerpc/code-patching: Move patch_exception() outside code-patching.c
powerpc/code-patching: Use test_trampoline for prefixed patch test
powerpc/code-patching: Fix patch_branch() return on out-of-range failure
powerpc/code-patching: Reorganise do_patch_instruction() to ease error handling
powerpc/code-patching: Fix unmap_patch_area() error handling
powerpc/code-patching: Fix error handling in do_patch_instruction()
...
With KUAP enabled, any kernel code which wants to access userspace
needs to be surrounded by disable-enable KUAP. But that is not
happening for BPF_PROBE_MEM load instruction. Though PPC32 does not
support read protection, considering the fact that PTR_TO_BTF_ID
(which uses BPF_PROBE_MEM mode) could either be a valid kernel pointer
or NULL but should never be a pointer to userspace address, execute
BPF_PROBE_MEM load only if addr is kernel address, otherwise set
dst_reg=0 and move on.
This will catch NULL, valid or invalid userspace pointers. Only bad
kernel pointer will be handled by BPF exception table.
[Alexei suggested for x86]
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211012123056.485795-9-hbathini@linux.ibm.com
BPF load instruction with BPF_PROBE_MEM mode can cause a fault
inside kernel. Append exception table for such instructions
within BPF program.
Unlike other archs which uses extable 'fixup' field to pass dest_reg
and nip, BPF exception table on PowerPC follows the generic PowerPC
exception table design, where it populates both fixup and extable
sections within BPF program. fixup section contains 3 instructions,
first 2 instructions clear dest_reg (lower & higher 32-bit registers)
and last instruction jumps to next instruction in the BPF code.
extable 'insn' field contains relative offset of the instruction and
'fixup' field contains relative offset of the fixup entry. Example
layout of BPF program with extable present:
+------------------+
| |
| |
0x4020 -->| lwz r28,4(r4) |
| |
| |
0x40ac -->| lwz r3,0(r24) |
| lwz r4,4(r24) |
| |
| |
|------------------|
0x4278 -->| li r28,0 | \
| li r27,0 | | fixup entry
| b 0x4024 | /
0x4284 -->| li r4,0 |
| li r3,0 |
| b 0x40b4 |
|------------------|
0x4290 -->| insn=0xfffffd90 | \ extable entry
| fixup=0xffffffe4 | /
0x4298 -->| insn=0xfffffe14 |
| fixup=0xffffffe8 |
+------------------+
(Addresses shown here are chosen random, not real)
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211012123056.485795-8-hbathini@linux.ibm.com
On PPC64 with KUAP enabled, any kernel code which wants to
access userspace needs to be surrounded by disable-enable KUAP.
But that is not happening for BPF_PROBE_MEM load instruction.
So, when BPF program tries to access invalid userspace address,
page-fault handler considers it as bad KUAP fault:
Kernel attempted to read user page (d0000000) - exploit attempt? (uid: 0)
Considering the fact that PTR_TO_BTF_ID (which uses BPF_PROBE_MEM
mode) could either be a valid kernel pointer or NULL but should
never be a pointer to userspace address, execute BPF_PROBE_MEM load
only if addr is kernel address, otherwise set dst_reg=0 and move on.
This will catch NULL, valid or invalid userspace pointers. Only bad
kernel pointer will be handled by BPF exception table.
[Alexei suggested for x86]
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211012123056.485795-7-hbathini@linux.ibm.com
BPF load instruction with BPF_PROBE_MEM mode can cause a fault
inside kernel. Append exception table for such instructions
within BPF program.
Unlike other archs which uses extable 'fixup' field to pass dest_reg
and nip, BPF exception table on PowerPC follows the generic PowerPC
exception table design, where it populates both fixup and extable
sections within BPF program. fixup section contains two instructions,
first instruction clears dest_reg and 2nd jumps to next instruction
in the BPF code. extable 'insn' field contains relative offset of
the instruction and 'fixup' field contains relative offset of the
fixup entry. Example layout of BPF program with extable present:
+------------------+
| |
| |
0x4020 -->| ld r27,4(r3) |
| |
| |
0x40ac -->| lwz r3,0(r4) |
| |
| |
|------------------|
0x4280 -->| li r27,0 | \ fixup entry
| b 0x4024 | /
0x4288 -->| li r3,0 |
| b 0x40b0 |
|------------------|
0x4290 -->| insn=0xfffffd90 | \ extable entry
| fixup=0xffffffec | /
0x4298 -->| insn=0xfffffe14 |
| fixup=0xffffffec |
+------------------+
(Addresses shown here are chosen random, not real)
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211012123056.485795-6-hbathini@linux.ibm.com
Define and use PPC_RAW_BRANCH() macro instead of open coding it. This
macro is used while adding BPF_PROBE_MEM support.
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211012123056.485795-5-hbathini@linux.ibm.com
In case of extra_pass, usual JIT passes are always skipped. So,
extra_pass is always false while calling bpf_jit_build_body() and
can be removed.
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211012123056.485795-3-hbathini@linux.ibm.com
