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| author | Christophe Leroy <christophe.leroy@csgroup.eu> | 2023-06-05 10:55:26 +0200 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2023-06-09 23:29:51 +1000 |
| commit | 0eb089a72fda3f7969e6277804bde75dc1474a14 (patch) | |
| tree | fbfafa2ce8546fa91db5ca77ac0c549317f3ddfc /arch/powerpc/kernel/interrupt.c | |
| parent | 396f2b0106ff343c61f7ae221dc6ae300f807760 (diff) | |
| download | linux-stable-0eb089a72fda3f7969e6277804bde75dc1474a14.tar.gz linux-stable-0eb089a72fda3f7969e6277804bde75dc1474a14.tar.bz2 linux-stable-0eb089a72fda3f7969e6277804bde75dc1474a14.zip | |
powerpc/interrupt: Don't read MSR from interrupt_exit_kernel_prepare()
A disassembly of interrupt_exit_kernel_prepare() shows a useless read
of MSR register. This is shown by r9 being re-used immediately without
doing anything with the value read.
c000e0e0: 60 00 00 00 nop
c000e0e4: 7d 3a c2 a6 mfmd_ap r9
c000e0e8: 7d 20 00 a6 mfmsr r9
c000e0ec: 7c 51 13 a6 mtspr 81,r2
c000e0f0: 81 3f 00 84 lwz r9,132(r31)
c000e0f4: 71 29 80 00 andi. r9,r9,32768
This is due to the use of local_irq_save(). The flags read by
local_irq_save() are never used, use local_irq_disable() instead.
Fixes: 13799748b957 ("powerpc/64: use interrupt restart table to speed up return from interrupt")
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/df36c6205ab64326fb1b991993c82057e92ace2f.1685955214.git.christophe.leroy@csgroup.eu
Diffstat (limited to 'arch/powerpc/kernel/interrupt.c')
| -rw-r--r-- | arch/powerpc/kernel/interrupt.c | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/arch/powerpc/kernel/interrupt.c b/arch/powerpc/kernel/interrupt.c index e34c72285b4e..f3fc5fe919d9 100644 --- a/arch/powerpc/kernel/interrupt.c +++ b/arch/powerpc/kernel/interrupt.c @@ -368,7 +368,6 @@ void preempt_schedule_irq(void); notrace unsigned long interrupt_exit_kernel_prepare(struct pt_regs *regs) { - unsigned long flags; unsigned long ret = 0; unsigned long kuap; bool stack_store = read_thread_flags() & _TIF_EMULATE_STACK_STORE; @@ -392,7 +391,7 @@ notrace unsigned long interrupt_exit_kernel_prepare(struct pt_regs *regs) kuap = kuap_get_and_assert_locked(); - local_irq_save(flags); + local_irq_disable(); if (!arch_irq_disabled_regs(regs)) { /* Returning to a kernel context with local irqs enabled. */ |