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| author | John David Anglin <dave.anglin@bell.net> | 2019-04-14 19:20:40 -0400 |
|---|---|---|
| committer | Helge Deller <deller@gmx.de> | 2019-05-03 23:47:40 +0200 |
| commit | 9e5c602186a692a7e848c0da17aed40f49d30519 (patch) | |
| tree | 845499e6cc5d1ee17c786233d9a427ab44c2bb6b /arch/parisc/kernel/syscall.S | |
| parent | 6c63ef80014b60ab13bee7e683d0a95521bb7fdd (diff) | |
| download | linux-9e5c602186a692a7e848c0da17aed40f49d30519.tar.bz2 | |
parisc: Use ldcw instruction for SMP spinlock release barrier
There are only a couple of instructions that can function as a memory
barrier on parisc. Currently, we use the sync instruction as a memory
barrier when releasing a spinlock. However, the ldcw instruction is a
better barrier when we have a handy memory location since it operates in
the cache on coherent machines.
This patch updates the spinlock release code to use ldcw. I also
changed the "stw,ma" instructions to "stw" instructions as it is not an
adequate barrier.
Signed-off-by: John David Anglin <dave.anglin@bell.net>
Signed-off-by: Helge Deller <deller@gmx.de>
Diffstat (limited to 'arch/parisc/kernel/syscall.S')
| -rw-r--r-- | arch/parisc/kernel/syscall.S | 16 |
1 files changed, 12 insertions, 4 deletions
diff --git a/arch/parisc/kernel/syscall.S b/arch/parisc/kernel/syscall.S index 4f77bd9be66b..e2b4c8d81275 100644 --- a/arch/parisc/kernel/syscall.S +++ b/arch/parisc/kernel/syscall.S @@ -640,7 +640,9 @@ cas_action: sub,<> %r28, %r25, %r0 2: stw %r24, 0(%r26) /* Free lock */ - sync +#ifdef CONFIG_SMP + LDCW 0(%sr2,%r20), %r1 /* Barrier */ +#endif stw %r20, 0(%sr2,%r20) #if ENABLE_LWS_DEBUG /* Clear thread register indicator */ @@ -655,7 +657,9 @@ cas_action: 3: /* Error occurred on load or store */ /* Free lock */ - sync +#ifdef CONFIG_SMP + LDCW 0(%sr2,%r20), %r1 /* Barrier */ +#endif stw %r20, 0(%sr2,%r20) #if ENABLE_LWS_DEBUG stw %r0, 4(%sr2,%r20) @@ -857,7 +861,9 @@ cas2_action: cas2_end: /* Free lock */ - sync +#ifdef CONFIG_SMP + LDCW 0(%sr2,%r20), %r1 /* Barrier */ +#endif stw %r20, 0(%sr2,%r20) /* Enable interrupts */ ssm PSW_SM_I, %r0 @@ -868,7 +874,9 @@ cas2_end: 22: /* Error occurred on load or store */ /* Free lock */ - sync +#ifdef CONFIG_SMP + LDCW 0(%sr2,%r20), %r1 /* Barrier */ +#endif stw %r20, 0(%sr2,%r20) ssm PSW_SM_I, %r0 ldo 1(%r0),%r28 |