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lib/crypto: x86/sha1: Follow the normal %rbp convention

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Some of the SHA-1 assembly functions push callee-save GPRs to the stack
*before* they set up the frame pointer (%rbp).  (They are leaf
functions, but they need to set up a frame pointer anyway because they
allocate a 16- or 32-byte-aligned buffer on the stack.)

As a result, during these functions, 8(%rbp) doesn't contain a return
address like it is supposed to.

This differs from the convention used by C code, and it interferes with
the frame pointer unwinder (CONFIG_UNWINDER_FRAME_POINTER=y).
Specifically, if a call trace is dumped in these functions, then all
entries are populated purely from the fallback scan of the entire stack:

    RIP: 0010:sha1_transform_avx2+0x1921/0x1ea0
    [...]
    Call Trace:
     <TASK>
     ? sha1_transform_avx+0x2a9/0xc90
     ? sha1_blocks_avx2+0x78/0x140
     ? kernel_fpu_end+0x2d/0x40
     ? sha1_blocks_avx2+0x52/0x140
     ? sha1_update+0x77/0x220
     [...]
     ? do_syscall_64+0x6f/0x3e0

With this fix to follow the normal %rbp convention, the call trace is
generated reliably:

    RIP: 0010:sha1_transform_avx2+0x66e/0x1ea0
    [...]
    Call Trace:
     <TASK>
     sha1_blocks_avx2+0x78/0x140
     sha1_update+0x77/0x220
     [...]
     do_syscall_64+0x6f/0x3e0

Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://patch.msgid.link/20261011134843.166585-2-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
This commit is contained in:
Eric Biggers 2026-10-11 15:48:41 +02:00
parent 6a50ce0af5
commit 0b173877fb
2 changed files with 10 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
lib/crypto/x86/sha1-avx2-asm.S
View File

@ -622,6 +622,9 @@
.macro SHA1_VECTOR_ASM name
SYM_FUNC_START(\name)
push %rbp
mov %rsp, %rbp
push %rbx
push %r12
push %r13
@ -631,8 +634,6 @@
RESERVE_STACK = (W_SIZE*4 + 8+24)
/* Align stack */
push %rbp
mov %rsp, %rbp
and $~(0x20-1), %rsp
sub $RESERVE_STACK, %rsp
@ -651,14 +652,13 @@
avx2_zeroupper
mov %rbp, %rsp
pop %rbp
lea -40(%rbp), %rsp
pop %r15
pop %r14
pop %r13
pop %r12
pop %rbx
pop %rbp
RET

9
lib/crypto/x86/sha1-ssse3-and-avx.S
View File

@ -69,11 +69,12 @@
.macro SHA1_VECTOR_ASM name
SYM_FUNC_START(\name)
push %rbx
push %r12
push %rbp
mov %rsp, %rbp
push %rbx
push %r12
sub $64, %rsp # allocate workspace
and $~15, %rsp # align stack
@ -95,10 +96,10 @@
xor %eax, %eax
rep stosq
mov %rbp, %rsp # deallocate workspace
pop %rbp
lea -16(%rbp), %rsp # deallocate workspace
pop %r12
pop %rbx
pop %rbp
RET
SYM_FUNC_END(\name)