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| author | Christophe Leroy <christophe.leroy@csgroup.eu> | 2021-08-23 08:24:20 +0000 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2021-08-26 21:21:07 +1000 |
| commit | 133c17a1788d68c9fff59d5f724a4ba14647a16d (patch) | |
| tree | ed5d3acfc1e6aff4fe098d583bbed5a08972a4e5 /arch/powerpc/sysdev/fsl_rio.c | |
| parent | d9db6e420268b2d561731468a31f0b15e2e9a145 (diff) | |
| download | lwn-133c17a1788d68c9fff59d5f724a4ba14647a16d.tar.gz lwn-133c17a1788d68c9fff59d5f724a4ba14647a16d.zip | |
powerpc: Remove MSR_PR check in interrupt_exit_{user/kernel}_prepare()
In those hot functions that are called at every interrupt, any saved
cycle is worth it.
interrupt_exit_user_prepare() and interrupt_exit_kernel_prepare() are
called from three places:
- From entry_32.S
- From interrupt_64.S
- From interrupt_exit_user_restart() and interrupt_exit_kernel_restart()
In entry_32.S, there are inambiguously called based on MSR_PR:
interrupt_return:
lwz r4,_MSR(r1)
addi r3,r1,STACK_FRAME_OVERHEAD
andi. r0,r4,MSR_PR
beq .Lkernel_interrupt_return
bl interrupt_exit_user_prepare
...
.Lkernel_interrupt_return:
bl interrupt_exit_kernel_prepare
In interrupt_64.S, that's similar:
interrupt_return_\srr\():
ld r4,_MSR(r1)
andi. r0,r4,MSR_PR
beq interrupt_return_\srr\()_kernel
interrupt_return_\srr\()_user: /* make backtraces match the _kernel variant */
addi r3,r1,STACK_FRAME_OVERHEAD
bl interrupt_exit_user_prepare
...
interrupt_return_\srr\()_kernel:
addi r3,r1,STACK_FRAME_OVERHEAD
bl interrupt_exit_kernel_prepare
In interrupt_exit_user_restart() and interrupt_exit_kernel_restart(),
MSR_PR is verified respectively by BUG_ON(!user_mode(regs)) and
BUG_ON(user_mode(regs)) prior to calling interrupt_exit_user_prepare()
and interrupt_exit_kernel_prepare().
The verification in interrupt_exit_user_prepare() and
interrupt_exit_kernel_prepare() are therefore useless and can be removed.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Acked-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/385ead49ccb66a259b25fee3eebf0bd4094068f3.1629707037.git.christophe.leroy@csgroup.eu
Diffstat (limited to 'arch/powerpc/sysdev/fsl_rio.c')
0 files changed, 0 insertions, 0 deletions