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| author | Jungseok Lee <jungseoklee85@gmail.com> | 2015-12-04 12:02:25 +0100 |
|---|---|---|
| committer | Will Deacon <will.deacon@arm.com> | 2015-12-08 12:40:48 +0100 |
| commit | 6cdf9c7ca687e01840d0215437620a20263012fc (patch) | |
| tree | 096f89d35adbe535b681e885c0214ea9eee7b463 /arch/arm64/kernel/entry.S | |
| parent | arm64: Clear out any singlestep state on a ptrace detach operation (diff) | |
| download | linux-6cdf9c7ca687e01840d0215437620a20263012fc.tar.xz linux-6cdf9c7ca687e01840d0215437620a20263012fc.zip | |
arm64: Store struct thread_info in sp_el0
There is need for figuring out how to manage struct thread_info data when
IRQ stack is introduced. struct thread_info information should be copied
to IRQ stack under the current thread_info calculation logic whenever
context switching is invoked. This is too expensive to keep supporting
the approach.
Instead, this patch pays attention to sp_el0 which is an unused scratch
register in EL1 context. sp_el0 utilization not only simplifies the
management, but also prevents text section size from being increased
largely due to static allocated IRQ stack as removing masking operation
using THREAD_SIZE in many places.
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Jungseok Lee <jungseoklee85@gmail.com>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch/arm64/kernel/entry.S')
| -rw-r--r-- | arch/arm64/kernel/entry.S | 15 |
1 files changed, 12 insertions, 3 deletions
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index e5b25389c48f..245fa6837880 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -88,7 +88,8 @@ .if \el == 0 mrs x21, sp_el0 - get_thread_info tsk // Ensure MDSCR_EL1.SS is clear, + mov tsk, sp + and tsk, tsk, #~(THREAD_SIZE - 1) // Ensure MDSCR_EL1.SS is clear, ldr x19, [tsk, #TI_FLAGS] // since we can unmask debug disable_step_tsk x19, x20 // exceptions when scheduling. .else @@ -108,6 +109,13 @@ .endif /* + * Set sp_el0 to current thread_info. + */ + .if \el == 0 + msr sp_el0, tsk + .endif + + /* * Registers that may be useful after this macro is invoked: * * x21 - aborted SP @@ -164,8 +172,7 @@ alternative_endif .endm .macro get_thread_info, rd - mov \rd, sp - and \rd, \rd, #~(THREAD_SIZE - 1) // top of stack + mrs \rd, sp_el0 .endm /* @@ -599,6 +606,8 @@ ENTRY(cpu_switch_to) ldp x29, x9, [x8], #16 ldr lr, [x8] mov sp, x9 + and x9, x9, #~(THREAD_SIZE - 1) + msr sp_el0, x9 ret ENDPROC(cpu_switch_to) |