diff options
| author | Andi Kleen <ak@suse.de> | 2006-09-26 10:52:28 +0200 |
|---|---|---|
| committer | Andi Kleen <andi@basil.nowhere.org> | 2006-09-26 10:52:28 +0200 |
| commit | 9a0b26e6bc4ae1979d9bcc6194e57a71b2b5cac6 (patch) | |
| tree | 01601a502007b85d4fc88f79de7a93c257ef9d97 /arch/x86_64/lib/rwlock.S | |
| parent | b4062b16094038334d9bbadac0397a3fc9e981b0 (diff) | |
[PATCH] Clean up read write lock assembly
- Move the slow path fallbacks to their own assembly files
This makes them much easier to read and is needed for the next change.
- Add CFI annotations for unwinding (XXX need review)
- Remove constant case which can never happen with out of line spinlocks
- Use patchable LOCK prefixes
- Don't use lock sections anymore for inline code because they can't
be expressed by the unwinder (this adds one taken jump to the lock
fast path)
Cc: jbeulich@novell.com
Signed-off-by: Andi Kleen <ak@suse.de>
Diffstat (limited to 'arch/x86_64/lib/rwlock.S')
| -rw-r--r-- | arch/x86_64/lib/rwlock.S | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/arch/x86_64/lib/rwlock.S b/arch/x86_64/lib/rwlock.S new file mode 100644 index 00000000000..0cde1f80731 --- /dev/null +++ b/arch/x86_64/lib/rwlock.S @@ -0,0 +1,38 @@ +/* Slow paths of read/write spinlocks. */ + +#include <linux/linkage.h> +#include <asm/rwlock.h> +#include <asm/alternative-asm.i> +#include <asm/dwarf2.h> + +/* rdi: pointer to rwlock_t */ +ENTRY(__write_lock_failed) + CFI_STARTPROC + LOCK_PREFIX + addl $RW_LOCK_BIAS,(%rdi) +1: rep + nop + cmpl $RW_LOCK_BIAS,(%rdi) + jne 1b + LOCK_PREFIX + subl $RW_LOCK_BIAS,(%rdi) + jnz __write_lock_failed + ret + CFI_ENDPROC +END(__write_lock_failed) + +/* rdi: pointer to rwlock_t */ +ENTRY(__read_lock_failed) + CFI_STARTPROC + LOCK_PREFIX + incl (%rdi) +1: rep + nop + cmpl $1,(%rdi) + js 1b + LOCK_PREFIX + decl (%rdi) + js __read_lock_failed + ret + CFI_ENDPROC +END(__read_lock_failed) |