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crypto: x86/aes - Don't use %rbp as temporary register

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When using the "aes-asm" implementation of AES (*not* the AES-NI
implementation) on an x86_64, v4.12-rc1 kernel with lockdep enabled, the
following warning was reported, along with a long unwinder dump:

	WARNING: kernel stack regs at ffffc90000643558 in kworker/u4:2:155 has bad 'bp' value 000000000000001c

The problem is that aes_enc_block() and aes_dec_block() use %rbp as a
temporary register, which breaks stack traces if an interrupt occurs.

Fix this by replacing %rbp with %r9, which was being used to hold the
saved value of %rbp.  This required rearranging the AES round macro
slightly since %r9d cannot be used as the target of a move from %ah-%dh.

Performance is essentially unchanged --- actually about 0.2% faster than
before.  Interestingly, I also measured aes-generic as being nearly 7%
faster than aes-asm, so perhaps aes-asm has outlived its usefulness...

Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Eric Biggers 2017-05-16 21:03:08 -07:00 committed by Herbert Xu
parent 248c65056c
commit 9417cd1c51
1 changed files with 22 additions and 25 deletions
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47
arch/x86/crypto/aes-x86_64-asm_64.S
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@ -42,17 +42,15 @@
#define R5E %esi
#define R6 %rdi
#define R6E %edi
#define R7 %rbp
#define R7E %ebp
#define R7 %r9 /* don't use %rbp; it breaks stack traces */
#define R7E %r9d
#define R8 %r8
#define R9 %r9
#define R10 %r10
#define R11 %r11
#define prologue(FUNC,KEY,B128,B192,r1,r2,r3,r4,r5,r6,r7,r8,r9,r10,r11) \
#define prologue(FUNC,KEY,B128,B192,r1,r2,r5,r6,r7,r8,r9,r10,r11) \
ENTRY(FUNC); \
movq r1,r2; \
movq r3,r4; \
leaq KEY+48(r8),r9; \
movq r10,r11; \
movl (r7),r5 ## E; \
@ -70,9 +68,8 @@
je B192; \
leaq 32(r9),r9;
#define epilogue(FUNC,r1,r2,r3,r4,r5,r6,r7,r8,r9) \
#define epilogue(FUNC,r1,r2,r5,r6,r7,r8,r9) \
movq r1,r2; \
movq r3,r4; \
movl r5 ## E,(r9); \
movl r6 ## E,4(r9); \
movl r7 ## E,8(r9); \
@ -88,12 +85,12 @@
movl TAB(,r6,4),r6 ## E; \
roll $16,r2 ## E; \
shrl $16,r4 ## E; \
movzbl r4 ## H,r7 ## E; \
movzbl r4 ## L,r4 ## E; \
movzbl r4 ## L,r7 ## E; \
movzbl r4 ## H,r4 ## E; \
xorl OFFSET(r8),ra ## E; \
xorl OFFSET+4(r8),rb ## E; \
xorl TAB+3072(,r7,4),r5 ## E;\
xorl TAB+2048(,r4,4),r6 ## E;\
xorl TAB+3072(,r4,4),r5 ## E;\
xorl TAB+2048(,r7,4),r6 ## E;\
movzbl r1 ## L,r7 ## E; \
movzbl r1 ## H,r4 ## E; \
movl TAB+1024(,r4,4),r4 ## E;\
@ -101,19 +98,19 @@
roll $16,r1 ## E; \
shrl $16,r3 ## E; \
xorl TAB(,r7,4),r5 ## E; \
movzbl r3 ## H,r7 ## E; \
movzbl r3 ## L,r3 ## E; \
xorl TAB+3072(,r7,4),r4 ## E;\
xorl TAB+2048(,r3,4),r5 ## E;\
movzbl r1 ## H,r7 ## E; \
movzbl r1 ## L,r3 ## E; \
movzbl r3 ## L,r7 ## E; \
movzbl r3 ## H,r3 ## E; \
xorl TAB+3072(,r3,4),r4 ## E;\
xorl TAB+2048(,r7,4),r5 ## E;\
movzbl r1 ## L,r7 ## E; \
movzbl r1 ## H,r3 ## E; \
shrl $16,r1 ## E; \
xorl TAB+3072(,r7,4),r6 ## E;\
movl TAB+2048(,r3,4),r3 ## E;\
movzbl r1 ## H,r7 ## E; \
movzbl r1 ## L,r1 ## E; \
xorl TAB+1024(,r7,4),r6 ## E;\
xorl TAB(,r1,4),r3 ## E; \
xorl TAB+3072(,r3,4),r6 ## E;\
movl TAB+2048(,r7,4),r3 ## E;\
movzbl r1 ## L,r7 ## E; \
movzbl r1 ## H,r1 ## E; \
xorl TAB+1024(,r1,4),r6 ## E;\
xorl TAB(,r7,4),r3 ## E; \
movzbl r2 ## H,r1 ## E; \
movzbl r2 ## L,r7 ## E; \
shrl $16,r2 ## E; \
@ -131,9 +128,9 @@
movl r4 ## E,r2 ## E;
#define entry(FUNC,KEY,B128,B192) \
prologue(FUNC,KEY,B128,B192,R2,R8,R7,R9,R1,R3,R4,R6,R10,R5,R11)
prologue(FUNC,KEY,B128,B192,R2,R8,R1,R3,R4,R6,R10,R5,R11)
#define return(FUNC) epilogue(FUNC,R8,R2,R9,R7,R5,R6,R3,R4,R11)
#define return(FUNC) epilogue(FUNC,R8,R2,R5,R6,R3,R4,R11)
#define encrypt_round(TAB,OFFSET) \
round(TAB,OFFSET,R1,R2,R3,R4,R5,R6,R7,R10,R5,R6,R3,R4) \