From: Eric Biggers <ebiggers@xxxxxxxxxx> 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@xxxxxxxxxx> --- arch/x86/crypto/aes-x86_64-asm_64.S | 47 +++++++++++++++++-------------------- 1 file changed, 22 insertions(+), 25 deletions(-) diff --git a/arch/x86/crypto/aes-x86_64-asm_64.S b/arch/x86/crypto/aes-x86_64-asm_64.S index 910565547163..8739cf7795de 100644 --- a/arch/x86/crypto/aes-x86_64-asm_64.S +++ b/arch/x86/crypto/aes-x86_64-asm_64.S @@ -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) \ -- 2.13.0
