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| author | James Morse <james.morse@arm.com> | 2018-01-08 15:38:06 +0000 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2018-01-13 10:44:33 +0000 |
| commit | 6d99b68933fbcf51f84fcbba49246ce1209ec193 (patch) | |
| tree | 894dd012b15f34f5c31f952fb52fc51485f24e9b /arch/arm64/include/asm/percpu.h | |
| parent | c97e166e54b662717d20ec2e36761758d2b6a7c2 (diff) | |
| download | lwn-6d99b68933fbcf51f84fcbba49246ce1209ec193.tar.gz lwn-6d99b68933fbcf51f84fcbba49246ce1209ec193.zip | |
arm64: alternatives: use tpidr_el2 on VHE hosts
Now that KVM uses tpidr_el2 in the same way as Linux's cpu_offset in
tpidr_el1, merge the two. This saves KVM from save/restoring tpidr_el1
on VHE hosts, and allows future code to blindly access per-cpu variables
without triggering world-switch.
Signed-off-by: James Morse <james.morse@arm.com>
Reviewed-by: Christoffer Dall <cdall@linaro.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/include/asm/percpu.h')
| -rw-r--r-- | arch/arm64/include/asm/percpu.h | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/arch/arm64/include/asm/percpu.h b/arch/arm64/include/asm/percpu.h index 3bd498e4de4c..43393208229e 100644 --- a/arch/arm64/include/asm/percpu.h +++ b/arch/arm64/include/asm/percpu.h @@ -16,11 +16,15 @@ #ifndef __ASM_PERCPU_H #define __ASM_PERCPU_H +#include <asm/alternative.h> #include <asm/stack_pointer.h> static inline void set_my_cpu_offset(unsigned long off) { - asm volatile("msr tpidr_el1, %0" :: "r" (off) : "memory"); + asm volatile(ALTERNATIVE("msr tpidr_el1, %0", + "msr tpidr_el2, %0", + ARM64_HAS_VIRT_HOST_EXTN) + :: "r" (off) : "memory"); } static inline unsigned long __my_cpu_offset(void) @@ -31,7 +35,10 @@ static inline unsigned long __my_cpu_offset(void) * We want to allow caching the value, so avoid using volatile and * instead use a fake stack read to hazard against barrier(). */ - asm("mrs %0, tpidr_el1" : "=r" (off) : + asm(ALTERNATIVE("mrs %0, tpidr_el1", + "mrs %0, tpidr_el2", + ARM64_HAS_VIRT_HOST_EXTN) + : "=r" (off) : "Q" (*(const unsigned long *)current_stack_pointer)); return off; |