From 8118c247a75ae95169f0a9a539dfc661ffda8bc5 Mon Sep 17 00:00:00 2001 From: Mathias Krause Date: Tue, 6 Jul 2021 15:27:14 +0200 Subject: crypto: curve25519-x86_64: solve register constraints with reserved registers The register constraints for the inline assembly in fsqr() and fsqr2() are pretty tight on what the compiler may assign to the remaining three register variables. The clobber list only allows the following to be used: RDI, RSI, RBP and R12. With RAP reserving R12 and a kernel having CONFIG_FRAME_POINTER=y, claiming RBP, there are only two registers left so the compiler rightfully complains about impossible constraints. Provide alternatives that'll allow a memory reference for 'out' to solve the allocation constraint dilemma for this configuration. Signed-off-by: Mathias Krause Signed-off-by: Jason A. Donenfeld --- src/crypto/zinc/curve25519/curve25519-x86_64.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/src/crypto/zinc/curve25519/curve25519-x86_64.c b/src/crypto/zinc/curve25519/curve25519-x86_64.c index 79716c4..67f55af 100644 --- a/src/crypto/zinc/curve25519/curve25519-x86_64.c +++ b/src/crypto/zinc/curve25519/curve25519-x86_64.c @@ -581,7 +581,7 @@ static inline void fsqr(u64 *out, const u64 *f, u64 *tmp) " cmovc %%rdx, %%rax;" " add %%rax, %%r8;" " movq %%r8, 0(%0);" - : "+&r" (tmp), "+&r" (f), "+&r" (out) + : "+&r,&r" (tmp), "+&r,&r" (f), "+&r,m" (out) : : "%rax", "%rcx", "%rdx", "%r8", "%r9", "%r10", "%r11", "%rbx", "%r13", "%r14", "%r15", "memory", "cc" ); @@ -743,7 +743,7 @@ static inline void fsqr2(u64 *out, const u64 *f, u64 *tmp) " cmovc %%rdx, %%rax;" " add %%rax, %%r8;" " movq %%r8, 32(%0);" - : "+&r" (tmp), "+&r" (f), "+&r" (out) + : "+&r,&r" (tmp), "+&r,&r" (f), "+&r,m" (out) : : "%rax", "%rcx", "%rdx", "%r8", "%r9", "%r10", "%r11", "%rbx", "%r13", "%r14", "%r15", "memory", "cc" ); -- cgit v1.2.3