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- From 7c847235e8f0e0b877c505f19733b417bb65ff2e Mon Sep 17 00:00:00 2001
- From: Gilles Peskine <[email protected]>
- Date: Tue, 14 Sep 2021 00:13:05 +0200
- Subject: [PATCH] x86_64 MULADDC assembly: add missing constraints about memory
- MULADDC_CORE reads from (%%rsi) and writes to (%%rdi). This fragment is
- repeated up to 16 times, and %%rsi and %%rdi are s and d on entry
- respectively. Hence the complete asm statement reads 16 64-bit words
- from memory starting at s, and writes 16 64-bit words starting at d.
- Without any declaration of modified memory, Clang 12 and Clang 13 generated
- non-working code for mbedtls_mpi_mod_exp. The constraints make the unit
- tests pass with Clang 12.
- Signed-off-by: Gilles Peskine <[email protected]>
- ---
- include/mbedtls/bn_mul.h | 6 +++---
- 1 file changed, 3 insertions(+), 3 deletions(-)
- diff --git a/include/mbedtls/bn_mul.h b/include/mbedtls/bn_mul.h
- index 6f1201bf50a..f84f9650ddc 100644
- --- a/include/mbedtls/bn_mul.h
- +++ b/include/mbedtls/bn_mul.h
- @@ -256,9 +256,9 @@
- "addq $8, %%rdi\n"
-
- #define MULADDC_STOP \
- - : "+c" (c), "+D" (d), "+S" (s) \
- - : "b" (b) \
- - : "rax", "rdx", "r8" \
- + : "+c" (c), "+D" (d), "+S" (s), "+m" (*(uint64_t (*)[16]) d) \
- + : "b" (b), "m" (*(const uint64_t (*)[16]) s) \
- + : "rax", "rdx", "r8" \
- );
-
- #endif /* AMD64 */
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