diff options
| author | Jisheng Zhang <jszhang@kernel.org> | 2025-04-10 07:05:24 +0000 |
|---|---|---|
| committer | Palmer Dabbelt <palmer@rivosinc.com> | 2025-05-08 10:01:00 -0700 |
| commit | 62135bf660b2c3887e22f33d3adbefedb4dc9c7a (patch) | |
| tree | fb5d7d06864069075f24c8473087ffdfb2944e67 | |
| parent | 19500c6dbc5c348564a6513c801ab0889300565a (diff) | |
riscv: uaccess: use input constraints for ptr of __put_user()
Putting ptr in the inputs as opposed to output may seem incorrect but
this is done for a few reasons:
- Not having it in the output permits the use of asm goto in a
subsequent patch. There are bugs in gcc [1] which would otherwise
prevent it.
- Since the output memory is userspace there isn't any real benefit from
telling the compiler about the memory clobber.
- x86, arm and powerpc all use this technique.
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113921 # 1
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
[Cyril Bur: Rewritten commit message]
Signed-off-by: Cyril Bur <cyrilbur@tenstorrent.com>
Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Link: https://lore.kernel.org/r/20250410070526.3160847-4-cyrilbur@tenstorrent.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
| -rw-r--r-- | arch/riscv/include/asm/uaccess.h | 18 |
1 files changed, 9 insertions, 9 deletions
diff --git a/arch/riscv/include/asm/uaccess.h b/arch/riscv/include/asm/uaccess.h index c9a461467bf4..da36057847f0 100644 --- a/arch/riscv/include/asm/uaccess.h +++ b/arch/riscv/include/asm/uaccess.h @@ -219,11 +219,11 @@ do { \ __typeof__(*(ptr)) __x = x; \ __asm__ __volatile__ ( \ "1:\n" \ - " " insn " %z2, %1\n" \ + " " insn " %z1, %2\n" \ "2:\n" \ _ASM_EXTABLE_UACCESS_ERR(1b, 2b, %0) \ - : "+r" (err), "=m" (*(ptr)) \ - : "rJ" (__x)); \ + : "+r" (err) \ + : "rJ" (__x), "m"(*(ptr))); \ } while (0) #ifdef CONFIG_64BIT @@ -236,16 +236,16 @@ do { \ u64 __x = (__typeof__((x)-(x)))(x); \ __asm__ __volatile__ ( \ "1:\n" \ - " sw %z3, %1\n" \ + " sw %z1, %3\n" \ "2:\n" \ - " sw %z4, %2\n" \ + " sw %z2, %4\n" \ "3:\n" \ _ASM_EXTABLE_UACCESS_ERR(1b, 3b, %0) \ _ASM_EXTABLE_UACCESS_ERR(2b, 3b, %0) \ - : "+r" (err), \ - "=m" (__ptr[__LSW]), \ - "=m" (__ptr[__MSW]) \ - : "rJ" (__x), "rJ" (__x >> 32)); \ + : "+r" (err) \ + : "rJ" (__x), "rJ" (__x >> 32), \ + "m" (__ptr[__LSW]), \ + "m" (__ptr[__MSW])); \ } while (0) #endif /* CONFIG_64BIT */ |