* [PATCH] MIPS: Remove open-coded cmpxchg() in set_pte()
@ 2019-02-02 2:01 Paul Burton
2019-02-04 21:18 ` Paul Burton
0 siblings, 1 reply; 2+ messages in thread
From: Paul Burton @ 2019-02-02 2:01 UTC (permalink / raw)
To: linux-mips; +Cc: Paul Burton
set_pte() contains an open coded version of cmpxchg() - it atomically
replaces the buddy pte's value if it is currently zero. Simplify the
code considerably by just using cmpxchg() instead of reinventing it.
Signed-off-by: Paul Burton <paul.burton@mips.com>
---
arch/mips/include/asm/pgtable.h | 45 ++-------------------------------
1 file changed, 2 insertions(+), 43 deletions(-)
diff --git a/arch/mips/include/asm/pgtable.h b/arch/mips/include/asm/pgtable.h
index 57933fc8fd98..6c13c1d44045 100644
--- a/arch/mips/include/asm/pgtable.h
+++ b/arch/mips/include/asm/pgtable.h
@@ -17,6 +17,7 @@
#include <asm/pgtable-64.h>
#endif
+#include <asm/cmpxchg.h>
#include <asm/io.h>
#include <asm/pgtable-bits.h>
@@ -204,49 +205,7 @@ static inline void set_pte(pte_t *ptep, pte_t pteval)
* Make sure the buddy is global too (if it's !none,
* it better already be global)
*/
-#ifdef CONFIG_SMP
- /*
- * For SMP, multiple CPUs can race, so we need to do
- * this atomically.
- */
- unsigned long page_global = _PAGE_GLOBAL;
- unsigned long tmp;
-
- if (kernel_uses_llsc && R10000_LLSC_WAR) {
- __asm__ __volatile__ (
- " .set push \n"
- " .set arch=r4000 \n"
- " .set noreorder \n"
- "1:" __LL "%[tmp], %[buddy] \n"
- " bnez %[tmp], 2f \n"
- " or %[tmp], %[tmp], %[global] \n"
- __SC "%[tmp], %[buddy] \n"
- " beqzl %[tmp], 1b \n"
- " nop \n"
- "2: \n"
- " .set pop \n"
- : [buddy] "+m" (buddy->pte), [tmp] "=&r" (tmp)
- : [global] "r" (page_global));
- } else if (kernel_uses_llsc) {
- __asm__ __volatile__ (
- " .set push \n"
- " .set "MIPS_ISA_ARCH_LEVEL" \n"
- " .set noreorder \n"
- "1:" __LL "%[tmp], %[buddy] \n"
- " bnez %[tmp], 2f \n"
- " or %[tmp], %[tmp], %[global] \n"
- __SC "%[tmp], %[buddy] \n"
- " beqz %[tmp], 1b \n"
- " nop \n"
- "2: \n"
- " .set pop \n"
- : [buddy] "+m" (buddy->pte), [tmp] "=&r" (tmp)
- : [global] "r" (page_global));
- }
-#else /* !CONFIG_SMP */
- if (pte_none(*buddy))
- pte_val(*buddy) = pte_val(*buddy) | _PAGE_GLOBAL;
-#endif /* CONFIG_SMP */
+ cmpxchg(&buddy->pte, 0, _PAGE_GLOBAL);
}
#endif
}
--
2.20.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] MIPS: Remove open-coded cmpxchg() in set_pte()
2019-02-02 2:01 [PATCH] MIPS: Remove open-coded cmpxchg() in set_pte() Paul Burton
@ 2019-02-04 21:18 ` Paul Burton
0 siblings, 0 replies; 2+ messages in thread
From: Paul Burton @ 2019-02-04 21:18 UTC (permalink / raw)
To: Paul Burton; +Cc: linux-mips, Paul Burton, linux-mips
Hello,
Paul Burton wrote:
> set_pte() contains an open coded version of cmpxchg() - it atomically
> replaces the buddy pte's value if it is currently zero. Simplify the
> code considerably by just using cmpxchg() instead of reinventing it.
>
> Signed-off-by: Paul Burton <paul.burton@mips.com>
Applied to mips-next.
Thanks,
Paul
[ This message was auto-generated; if you believe anything is incorrect
then please email paul.burton@mips.com to report it. ]
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