The following commit has been merged into the x86/asm branch of tip:
Commit-ID: dc8bd769e70ecae0916bf1b05acad6120c6bd6f0
Gitweb: https://git.kernel.org/tip/dc8bd769e70ecae0916bf1b05acad6120c6bd6f0
Author: Uros Bizjak <ubizjak@xxxxxxxxx>
AuthorDate: Sun, 23 Feb 2025 17:13:38 +01:00
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Sun, 23 Feb 2025 19:18:18 +01:00
x86/ioperm: Use atomic64_inc_return() in ksys_ioperm()
Use atomic64_inc_return(&ref) instead of atomic64_add_return(1, &ref)
to use optimized implementation on targets that define
atomic_inc_return() and to remove now unneeded initialization of the
%eax/%edx register pair before the call to atomic64_inc_return().
On x86_32 the code improves from:
1b0: b9 00 00 00 00 mov $0x0,%ecx
1b1: R_386_32 .bss
1b5: 89 43 0c mov %eax,0xc(%ebx)
1b8: 31 d2 xor %edx,%edx
1ba: b8 01 00 00 00 mov $0x1,%eax
1bf: e8 fc ff ff ff call 1c0 <ksys_ioperm+0xa8>
1c0: R_386_PC32 atomic64_add_return_cx8
1c4: 89 03 mov %eax,(%ebx)
1c6: 89 53 04 mov %edx,0x4(%ebx)
to:
1b0: be 00 00 00 00 mov $0x0,%esi
1b1: R_386_32 .bss
1b5: 89 43 0c mov %eax,0xc(%ebx)
1b8: e8 fc ff ff ff call 1b9 <ksys_ioperm+0xa1>
1b9: R_386_PC32 atomic64_inc_return_cx8
1bd: 89 03 mov %eax,(%ebx)
1bf: 89 53 04 mov %edx,0x4(%ebx)
Signed-off-by: Uros Bizjak <ubizjak@xxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20250223161355.3607-1-ubizjak@xxxxxxxxx
---
arch/x86/kernel/ioport.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kernel/ioport.c b/arch/x86/kernel/ioport.c
index e2fab3c..6290dd1 100644
--- a/arch/x86/kernel/ioport.c
+++ b/arch/x86/kernel/ioport.c
@@ -144,7 +144,7 @@ long ksys_ioperm(unsigned long from, unsigned long num, int turn_on)
* Update the sequence number to force a TSS update on return to
* user mode.
*/
- iobm->sequence = atomic64_add_return(1, &io_bitmap_sequence);
+ iobm->sequence = atomic64_inc_return(&io_bitmap_sequence);
return 0;
}
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