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| author |   Rohan McLure <rmclure@linux.ibm.com> | 2022-09-21 16:55:42 +1000 |
|---|---|---|
| committer |   Michael Ellerman <mpe@ellerman.id.au> | 2022-09-26 23:00:14 +1000 |
| commit | 2c27d4a419f627636b8c6038e55acb26df05c391 (patch) | |
| tree | 72ab274a06583565a00c0f757160d1042116b747 /arch/powerpc/include/asm/ppc_asm.h | |
| parent | powerpc: Remove asmlinkage from syscall handler definitions (diff) | |
| download | linux-dev-2c27d4a419f627636b8c6038e55acb26df05c391.tar.xz linux-dev-2c27d4a419f627636b8c6038e55acb26df05c391.zip | |
powerpc: Save caller r3 prior to system_call_exception
This reverts commit 8875f47b7681 ("powerpc/syscall: Save r3 in regs->orig_r3
").
Save caller's original r3 state to the kernel stackframe before entering
system_call_exception. This allows for user registers to be cleared by
the time system_call_exception is entered, reducing the influence of
user registers on speculation within the kernel.
Prior to this commit, orig_r3 was saved at the beginning of
system_call_exception. Instead, save orig_r3 while the user value is
still live in r3.
Also replicate this early save in 32-bit. A similar save was removed in
commit 6f76a01173cc ("powerpc/syscall: implement system call entry/exit
logic in C for PPC32") when 32-bit adopted system_call_exception. Revert
its removal of orig_r3 saves.
Signed-off-by: Rohan McLure <rmclure@linux.ibm.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220921065605.1051927-3-rmclure@linux.ibm.com
Diffstat (limited to 'arch/powerpc/include/asm/ppc_asm.h')
0 files changed, 0 insertions, 0 deletions