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MIPS: Remove open-coded cmpxchg() in set_pte() 

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>
Cc: linux-mips@vger.kernel.org
This commit is contained in:
Paul Burton 2019-02-02 02:01:02 +00:00
parent c8790d657b
commit 82f4f66ddf
No known key found for this signature in database
GPG Key ID: 3EA79FACB57500DD
1 changed files with 2 additions and 43 deletions
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45
arch/mips/include/asm/pgtable.h
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@ -17,6 +17,7 @@
#include <asm/pgtable-64.h> #include <asm/pgtable-64.h>
#endif #endif
#include <asm/cmpxchg.h>
#include <asm/io.h> #include <asm/io.h>
#include <asm/pgtable-bits.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, * Make sure the buddy is global too (if it's !none,
* it better already be global) * it better already be global)
*/ */
#ifdef CONFIG_SMP cmpxchg(&buddy->pte, 0, _PAGE_GLOBAL);
/*
* 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 */
} }
#endif #endif
} }