crypto: x86/cast6 - Fix RBP usage

Using RBP as a temporary register breaks frame pointer convention and
breaks stack traces when unwinding from an interrupt in the crypto code.

Use R15 instead of RBP.  R15 can't be used as the RID1 register because
of x86 instruction encoding limitations.  So use R15 for CTX and RDI for
CTX.  This means that CTX is no longer an implicit function argument.
Instead it needs to be explicitly copied from RDI.

Reported-by: Eric Biggers <ebiggers@google.com>
Reported-by: Peter Zijlstra <peterz@infradead.org>
Tested-by: Eric Biggers <ebiggers@google.com>
Acked-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/arch/x86/crypto/cast6-avx-x86_64-asm_64.S b/arch/x86/crypto/cast6-avx-x86_64-asm_64.S
index 952d3156a93312ff8c5a5c2c193132a89f7413da..7f30b6f0d72c15f402a69d621ecde1c283780266 100644 (file)
--- a/arch/x86/crypto/cast6-avx-x86_64-asm_64.S
+++ b/arch/x86/crypto/cast6-avx-x86_64-asm_64.S
@@ -47,7 +47,7 @@
 /**********************************************************************
   8-way AVX cast6
  **********************************************************************/
-#define CTX %rdi
+#define CTX %r15
 
 #define RA1 %xmm0
 #define RB1 %xmm1
@@ -70,8 +70,8 @@
 
 #define RTMP %xmm15
 
-#define RID1  %rbp
-#define RID1d %ebp
+#define RID1  %rdi
+#define RID1d %edi
 #define RID2  %rsi
 #define RID2d %esi
 
@@ -264,15 +264,17 @@
 .align 8
 __cast6_enc_blk8:
        /* input:
-        *      %rdi: ctx, CTX
+        *      %rdi: ctx
         *      RA1, RB1, RC1, RD1, RA2, RB2, RC2, RD2: blocks
         * output:
         *      RA1, RB1, RC1, RD1, RA2, RB2, RC2, RD2: encrypted blocks
         */
 
-       pushq %rbp;
+       pushq %r15;
        pushq %rbx;
 
+       movq %rdi, CTX;
+
        vmovdqa .Lbswap_mask, RKM;
        vmovd .Lfirst_mask, R1ST;
        vmovd .L32_mask, R32;
@@ -297,7 +299,7 @@ __cast6_enc_blk8:
        QBAR(11);
 
        popq %rbx;
-       popq %rbp;
+       popq %r15;
 
        vmovdqa .Lbswap_mask, RKM;
 
@@ -310,15 +312,17 @@ ENDPROC(__cast6_enc_blk8)
 .align 8
 __cast6_dec_blk8:
        /* input:
-        *      %rdi: ctx, CTX
+        *      %rdi: ctx
         *      RA1, RB1, RC1, RD1, RA2, RB2, RC2, RD2: encrypted blocks
         * output:
         *      RA1, RB1, RC1, RD1, RA2, RB2, RC2, RD2: decrypted blocks
         */
 
-       pushq %rbp;
+       pushq %r15;
        pushq %rbx;
 
+       movq %rdi, CTX;
+
        vmovdqa .Lbswap_mask, RKM;
        vmovd .Lfirst_mask, R1ST;
        vmovd .L32_mask, R32;
@@ -343,7 +347,7 @@ __cast6_dec_blk8:
        QBAR(0);
 
        popq %rbx;
-       popq %rbp;
+       popq %r15;
 
        vmovdqa .Lbswap_mask, RKM;
        outunpack_blocks(RA1, RB1, RC1, RD1, RTMP, RX, RKRF, RKM);
@@ -354,12 +358,14 @@ ENDPROC(__cast6_dec_blk8)
 
 ENTRY(cast6_ecb_enc_8way)
        /* input:
-        *      %rdi: ctx, CTX
+        *      %rdi: ctx
         *      %rsi: dst
         *      %rdx: src
         */
        FRAME_BEGIN
+       pushq %r15;
 
+       movq %rdi, CTX;
        movq %rsi, %r11;
 
        load_8way(%rdx, RA1, RB1, RC1, RD1, RA2, RB2, RC2, RD2);
@@ -368,18 +374,21 @@ ENTRY(cast6_ecb_enc_8way)
 
        store_8way(%r11, RA1, RB1, RC1, RD1, RA2, RB2, RC2, RD2);
 
+       popq %r15;
        FRAME_END
        ret;
 ENDPROC(cast6_ecb_enc_8way)
 
 ENTRY(cast6_ecb_dec_8way)
        /* input:
-        *      %rdi: ctx, CTX
+        *      %rdi: ctx
         *      %rsi: dst
         *      %rdx: src
         */
        FRAME_BEGIN
+       pushq %r15;
 
+       movq %rdi, CTX;
        movq %rsi, %r11;
 
        load_8way(%rdx, RA1, RB1, RC1, RD1, RA2, RB2, RC2, RD2);
@@ -388,20 +397,22 @@ ENTRY(cast6_ecb_dec_8way)
 
        store_8way(%r11, RA1, RB1, RC1, RD1, RA2, RB2, RC2, RD2);
 
+       popq %r15;
        FRAME_END
        ret;
 ENDPROC(cast6_ecb_dec_8way)
 
 ENTRY(cast6_cbc_dec_8way)
        /* input:
-        *      %rdi: ctx, CTX
+        *      %rdi: ctx
         *      %rsi: dst
         *      %rdx: src
         */
        FRAME_BEGIN
-
        pushq %r12;
+       pushq %r15;
 
+       movq %rdi, CTX;
        movq %rsi, %r11;
        movq %rdx, %r12;
 
@@ -411,8 +422,8 @@ ENTRY(cast6_cbc_dec_8way)
 
        store_cbc_8way(%r12, %r11, RA1, RB1, RC1, RD1, RA2, RB2, RC2, RD2);
 
+       popq %r15;
        popq %r12;
-
        FRAME_END
        ret;
 ENDPROC(cast6_cbc_dec_8way)
@@ -425,9 +436,10 @@ ENTRY(cast6_ctr_8way)
         *      %rcx: iv (little endian, 128bit)
         */
        FRAME_BEGIN
-
        pushq %r12;
+       pushq %r15
 
+       movq %rdi, CTX;
        movq %rsi, %r11;
        movq %rdx, %r12;
 
@@ -438,8 +450,8 @@ ENTRY(cast6_ctr_8way)
 
        store_ctr_8way(%r12, %r11, RA1, RB1, RC1, RD1, RA2, RB2, RC2, RD2);
 
+       popq %r15;
        popq %r12;
-
        FRAME_END
        ret;
 ENDPROC(cast6_ctr_8way)
@@ -452,7 +464,9 @@ ENTRY(cast6_xts_enc_8way)
         *      %rcx: iv (t ⊕ αⁿ ∈ GF(2¹²⁸))
         */
        FRAME_BEGIN
+       pushq %r15;
 
+       movq %rdi, CTX
        movq %rsi, %r11;
 
        /* regs <= src, dst <= IVs, regs <= regs xor IVs */
@@ -464,6 +478,7 @@ ENTRY(cast6_xts_enc_8way)
        /* dst <= regs xor IVs(in dst) */
        store_xts_8way(%r11, RA1, RB1, RC1, RD1, RA2, RB2, RC2, RD2);
 
+       popq %r15;
        FRAME_END
        ret;
 ENDPROC(cast6_xts_enc_8way)
@@ -476,7 +491,9 @@ ENTRY(cast6_xts_dec_8way)
         *      %rcx: iv (t ⊕ αⁿ ∈ GF(2¹²⁸))
         */
        FRAME_BEGIN
+       pushq %r15;
 
+       movq %rdi, CTX
        movq %rsi, %r11;
 
        /* regs <= src, dst <= IVs, regs <= regs xor IVs */
@@ -488,6 +505,7 @@ ENTRY(cast6_xts_dec_8way)
        /* dst <= regs xor IVs(in dst) */
        store_xts_8way(%r11, RA1, RB1, RC1, RD1, RA2, RB2, RC2, RD2);
 
+       popq %r15;
        FRAME_END
        ret;
 ENDPROC(cast6_xts_dec_8way)