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lib/crypto: x86/sha256: Follow the normal %rbp convention

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Some of the SHA-256 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:sha256_transform_rorx+0xd78/0x1120
    [...]
    Call Trace:
     <TASK>
     ? sha256_blocks_avx2+0x37/0x70
     ? __sha256_update+0x77/0x220
     ? sha256+0x9d/0x110
     [...]
     ? do_syscall_64+0x6f/0x3e0

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

    RIP: 0010:sha256_transform_rorx+0xdae/0x1120
    [...]
    Call Trace:
     <TASK>
     sha256_blocks_avx2+0x37/0x70
     __sha256_update+0x77/0x220
     sha256+0x9d/0x110
     [...]
     do_syscall_64+0x6f/0x3e0

Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://patch.msgid.link/20261011134843.166585-3-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
This commit is contained in:
Eric Biggers 2026-10-11 15:48:42 +02:00
parent 0b173877fb
commit cc76c9b82b
4 changed files with 18 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
lib/crypto/x86/sha256-avx-asm.S
View File

@ -345,13 +345,13 @@ a = TMP_
########################################################################
.text
SYM_FUNC_START(sha256_transform_avx)
pushq %rbp
movq %rsp, %rbp
pushq %rbx
pushq %r12
pushq %r13
pushq %r14
pushq %r15
pushq %rbp
movq %rsp, %rbp
subq $STACK_SIZE, %rsp # allocate stack space
and $~15, %rsp # align stack pointer
@ -445,13 +445,13 @@ SYM_FUNC_START(sha256_transform_avx)
cmp _INP_END(%rsp), INP
jne .Lloop0
mov %rbp, %rsp
popq %rbp
lea -40(%rbp), %rsp
popq %r15
popq %r14
popq %r13
popq %r12
popq %r12
popq %rbx
popq %rbp
RET
SYM_FUNC_END(sha256_transform_avx)

10
lib/crypto/x86/sha256-avx2-asm.S
View File

@ -522,15 +522,14 @@ STACK_SIZE = _CTX + _CTX_SIZE
########################################################################
.text
SYM_FUNC_START(sha256_transform_rorx)
pushq %rbp
mov %rsp, %rbp
pushq %rbx
pushq %r12
pushq %r13
pushq %r14
pushq %r15
push %rbp
mov %rsp, %rbp
subq $STACK_SIZE, %rsp
and $-32, %rsp # align rsp to 32 byte boundary
@ -704,14 +703,13 @@ SYM_FUNC_START(sha256_transform_rorx)
.Ldone_hash:
mov %rbp, %rsp
pop %rbp
lea -40(%rbp), %rsp
popq %r15
popq %r14
popq %r13
popq %r12
popq %rbx
popq %rbp
vzeroupper
RET
SYM_FUNC_END(sha256_transform_rorx)

9
lib/crypto/x86/sha256-ni-asm.S
View File

@ -276,10 +276,11 @@ SYM_FUNC_END(sha256_ni_transform)
// to taking better advantage of the CPU's SHA-256 and SIMD throughput.
//
SYM_FUNC_START(sha256_ni_finup2x)
// Allocate 128 bytes of stack space, 16-byte aligned.
push %rbx
push %rbp
mov %rsp, %rbp
push %rbx
// Allocate 128 bytes of stack space, 16-byte aligned.
sub $128, %rsp
and $~15, %rsp
@ -527,9 +528,9 @@ SYM_FUNC_START(sha256_ni_finup2x)
movdqu STATE1_A, 0*16(OUT1)
movdqu STATE1_B, 0*16(OUT2)
mov %rbp, %rsp
pop %rbp
lea -8(%rbp), %rsp
pop %rbx
pop %rbp
RET
SYM_FUNC_END(sha256_ni_finup2x)

8
lib/crypto/x86/sha256-ssse3-asm.S
View File

@ -352,13 +352,13 @@ a = TMP_
########################################################################
.text
SYM_FUNC_START(sha256_transform_ssse3)
pushq %rbp
mov %rsp, %rbp
pushq %rbx
pushq %r12
pushq %r13
pushq %r14
pushq %r15
pushq %rbp
mov %rsp, %rbp
subq $STACK_SIZE, %rsp
and $~15, %rsp
@ -456,13 +456,13 @@ SYM_FUNC_START(sha256_transform_ssse3)
cmp _INP_END(%rsp), INP
jne .Lloop0
mov %rbp, %rsp
popq %rbp
lea -40(%rbp), %rsp
popq %r15
popq %r14
popq %r13
popq %r12
popq %rbx
popq %rbp
RET
SYM_FUNC_END(sha256_transform_ssse3)