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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 | |
| 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
| -rw-r--r-- | arch/powerpc/kernel/entry_32.S | 1 | ||||
| -rw-r--r-- | arch/powerpc/kernel/interrupt_64.S | 2 | ||||
| -rw-r--r-- | arch/powerpc/kernel/syscall.c | 1 |
3 files changed, 3 insertions, 1 deletions
diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S index 2b5b0677d36c..497f04cde7dc 100644 --- a/arch/powerpc/kernel/entry_32.S +++ b/arch/powerpc/kernel/entry_32.S @@ -101,6 +101,7 @@ __kuep_unlock: .globl transfer_to_syscall transfer_to_syscall: + stw r3, ORIG_GPR3(r1) stw r11, GPR1(r1) stw r11, 0(r1) mflr r12 diff --git a/arch/powerpc/kernel/interrupt_64.S b/arch/powerpc/kernel/interrupt_64.S index a2d3abb48075..9d6c8c5e5634 100644 --- a/arch/powerpc/kernel/interrupt_64.S +++ b/arch/powerpc/kernel/interrupt_64.S @@ -81,6 +81,7 @@ _ASM_NOKPROBE_SYMBOL(system_call_vectored_\name) li r11,\trapnr std r11,_TRAP(r1) std r12,_CCR(r1) + std r3,ORIG_GPR3(r1) addi r10,r1,STACK_FRAME_OVERHEAD ld r11,exception_marker@toc(r2) std r11,-16(r10) /* "regshere" marker */ @@ -265,6 +266,7 @@ END_BTB_FLUSH_SECTION std r10,_LINK(r1) std r11,_TRAP(r1) std r12,_CCR(r1) + std r3,ORIG_GPR3(r1) addi r10,r1,STACK_FRAME_OVERHEAD ld r11,exception_marker@toc(r2) std r11,-16(r10) /* "regshere" marker */ diff --git a/arch/powerpc/kernel/syscall.c b/arch/powerpc/kernel/syscall.c index 81ace9e8b72b..64102a64fd84 100644 --- a/arch/powerpc/kernel/syscall.c +++ b/arch/powerpc/kernel/syscall.c @@ -25,7 +25,6 @@ notrace long system_call_exception(long r3, long r4, long r5, kuap_lock(); add_random_kstack_offset(); - regs->orig_gpr3 = r3; if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG)) BUG_ON(irq_soft_mask_return() != IRQS_ALL_DISABLED); |