Messages in this thread Patch in this message | | | From | Mark Rutland <> | Subject | [RFC PATCH 5/8] arm64: assembler: introduce ldr_this_cpu | Date | Thu, 15 Sep 2016 14:49:06 +0100 |
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Shortly we will want to load a percpu variable in the return from userspace path. We can save an instruction by folding the addition of the percpu offset into the load instruction, and this patch adds a new helper to do so.
At the same time, we clean up this_cpu_ptr for consistency. As with {adr,ldr,str}_l, we change the template to take the destination register first, and name this dst. Secondly, we rename the macro to adr_this_cpu, following the scheme of adr_l, and matching the newly added ldr_this_cpu.
Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: James Morse <james.morse@arm.com> Cc: Will Deacon <will.deacon@arm.com> --- arch/arm64/include/asm/assembler.h | 19 +++++++++++++++---- arch/arm64/kernel/entry.S | 2 +- 2 files changed, 16 insertions(+), 5 deletions(-)
diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h index d5025c6..265fd81 100644 --- a/arch/arm64/include/asm/assembler.h +++ b/arch/arm64/include/asm/assembler.h @@ -193,14 +193,25 @@ lr .req x30 // link register .endm /* + * @dst: Result of per_cpu(sym, smp_processor_id()) * @sym: The name of the per-cpu variable - * @reg: Result of per_cpu(sym, smp_processor_id()) * @tmp: scratch register */ - .macro this_cpu_ptr, sym, reg, tmp - adr_l \reg, \sym + .macro adr_this_cpu, dst, sym, tmp + adr_l \dst, \sym mrs \tmp, tpidr_el1 - add \reg, \reg, \tmp + add \dst, \dst, \tmp + .endm + + /* + * @dst: Result of READ_ONCE(per_cpu(sym, smp_processor_id())) + * @sym: The name of the per-cpu variable + * @tmp: scratch register + */ + .macro ldr_this_cpu dst, sym, tmp + adr_l \dst, \sym + mrs \tmp, tpidr_el1 + ldr \dst, [\dst, \tmp] .endm /* diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 441420c..52b4241 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -206,7 +206,7 @@ alternative_endif cmp x25, tsk b.ne 9998f - this_cpu_ptr irq_stack, x25, x26 + adr_this_cpu x25, irq_stack, x26 mov x26, #IRQ_STACK_START_SP add x26, x25, x26 -- 1.9.1
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