Re: [PATCH v1 01/27] x86/crypto: Adapt assembly for PIE support
From: Ingo Molnar <mingo@kernel.org>
Date: 2017-10-20 08:24:21
* Thomas Garnier [off-list ref] wrote:
Change the assembly code to use only relative references of symbols for the kernel to be PIE compatible. Position Independent Executable (PIE) support will allow to extended the KASLR randomization range below the -2G memory limit.
quoted hunk
diff --git a/arch/x86/crypto/aes-x86_64-asm_64.S b/arch/x86/crypto/aes-x86_64-asm_64.S index 8739cf7795de..86fa068e5e81 100644 --- a/arch/x86/crypto/aes-x86_64-asm_64.S +++ b/arch/x86/crypto/aes-x86_64-asm_64.S@@ -48,8 +48,12 @@ #define R10 %r10 #define R11 %r11 +/* Hold global for PIE suport */ +#define RBASE %r12 + #define prologue(FUNC,KEY,B128,B192,r1,r2,r5,r6,r7,r8,r9,r10,r11) \ ENTRY(FUNC); \ + pushq RBASE; \ movq r1,r2; \ leaq KEY+48(r8),r9; \ movq r10,r11; \@@ -74,54 +78,63 @@ movl r6 ## E,4(r9); \ movl r7 ## E,8(r9); \ movl r8 ## E,12(r9); \ + popq RBASE; \ ret; \ ENDPROC(FUNC); +#define round_mov(tab_off, reg_i, reg_o) \ + leaq tab_off(%rip), RBASE; \ + movl (RBASE,reg_i,4), reg_o; + +#define round_xor(tab_off, reg_i, reg_o) \ + leaq tab_off(%rip), RBASE; \ + xorl (RBASE,reg_i,4), reg_o; + #define round(TAB,OFFSET,r1,r2,r3,r4,r5,r6,r7,r8,ra,rb,rc,rd) \ movzbl r2 ## H,r5 ## E; \ movzbl r2 ## L,r6 ## E; \ - movl TAB+1024(,r5,4),r5 ## E;\ + round_mov(TAB+1024, r5, r5 ## E)\ movw r4 ## X,r2 ## X; \ - movl TAB(,r6,4),r6 ## E; \ + round_mov(TAB, r6, r6 ## E) \ roll $16,r2 ## E; \ shrl $16,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(,r4,4),r5 ## E;\ - xorl TAB+2048(,r7,4),r6 ## E;\ + round_xor(TAB+3072, r4, r5 ## E)\ + round_xor(TAB+2048, r7, r6 ## E)\ movzbl r1 ## L,r7 ## E; \ movzbl r1 ## H,r4 ## E; \ - movl TAB+1024(,r4,4),r4 ## E;\ + round_mov(TAB+1024, r4, r4 ## E)\ movw r3 ## X,r1 ## X; \ roll $16,r1 ## E; \ shrl $16,r3 ## E; \ - xorl TAB(,r7,4),r5 ## E; \ + round_xor(TAB, r7, r5 ## 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;\ + round_xor(TAB+3072, r3, r4 ## E)\ + round_xor(TAB+2048, r7, r5 ## E)\ movzbl r1 ## L,r7 ## E; \ movzbl r1 ## H,r3 ## E; \ shrl $16,r1 ## E; \ - xorl TAB+3072(,r3,4),r6 ## E;\ - movl TAB+2048(,r7,4),r3 ## E;\ + round_xor(TAB+3072, r3, r6 ## E)\ + round_mov(TAB+2048, r7, 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; \ + round_xor(TAB+1024, r1, r6 ## E)\ + round_xor(TAB, r7, r3 ## E) \ movzbl r2 ## H,r1 ## E; \ movzbl r2 ## L,r7 ## E; \ shrl $16,r2 ## E; \ - xorl TAB+3072(,r1,4),r3 ## E;\ - xorl TAB+2048(,r7,4),r4 ## E;\ + round_xor(TAB+3072, r1, r3 ## E)\ + round_xor(TAB+2048, r7, r4 ## E)\ movzbl r2 ## H,r1 ## E; \ movzbl r2 ## L,r2 ## E; \ xorl OFFSET+8(r8),rc ## E; \ xorl OFFSET+12(r8),rd ## E; \ - xorl TAB+1024(,r1,4),r3 ## E;\ - xorl TAB(,r2,4),r4 ## E; + round_xor(TAB+1024, r1, r3 ## E)\ + round_xor(TAB, r2, r4 ## E)
This appears to be adding unconditional overhead to a function that was moved to assembly to improve its performance. Thanks, Ingo