diff options
| author | Uros Bizjak <[email protected]> | 2024-03-19 18:16:46 +0100 |
|---|---|---|
| committer | Ingo Molnar <[email protected]> | 2024-03-20 12:04:38 +0100 |
| commit | 648337147d3550c1ca3d1b500e66dbda12e2d836 (patch) | |
| tree | 3122e80d008ebea46dbe1db2c9dafd2ab58e5f07 | |
| parent | d689863c1a60b9936b47a34fa5c3330de374f4fc (diff) | |
x86/asm: Use "m" operand constraint in WRUSSQ asm template
The WRUSSQ instruction uses a memory operand, so use "m"
operand constraint instead of forcing usage of pointer
register using "r" constraint. The generated assembly
code improves from:
6ece3: 48 8d 43 f8 lea -0x8(%rbx),%rax
...
6eceb: 66 48 0f 38 f5 18 wrussq %rbx,(%rax)
to:
6ecea: 66 48 0f 38 f5 43 f8 wrussq %rax,-0x8(%rbx)
Signed-off-by: Uros Bizjak <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: Ard Biesheuvel <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
| -rw-r--r-- | arch/x86/include/asm/special_insns.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/x86/include/asm/special_insns.h b/arch/x86/include/asm/special_insns.h index 0ee2ba589492..aec6e2d3aa1d 100644 --- a/arch/x86/include/asm/special_insns.h +++ b/arch/x86/include/asm/special_insns.h @@ -205,9 +205,9 @@ static inline void clwb(volatile void *__p) #ifdef CONFIG_X86_USER_SHADOW_STACK static inline int write_user_shstk_64(u64 __user *addr, u64 val) { - asm goto("1: wrussq %[val], (%[addr])\n" + asm goto("1: wrussq %[val], %[addr]\n" _ASM_EXTABLE(1b, %l[fail]) - :: [addr] "r" (addr), [val] "r" (val) + :: [addr] "m" (*addr), [val] "r" (val) :: fail); return 0; fail: |