Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 9417cd1c authored by Eric Biggers's avatar Eric Biggers Committed by Herbert Xu
Browse files

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



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: default avatarEric Biggers <ebiggers@google.com>
Reviewed-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent 248c6505

arch/x86/crypto/aes-x86_64-asm_64.S

+22 −25
Original line number Diff line number Diff line
@@ -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) \