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Subject[PATCH 4.9 43/66] arm64: assembler: introduce ldr_this_cpu
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4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Mark Rutland <mark.rutland@arm.com>

Commit 1b7e2296a822dfd2349960addc42a139360ce769 upstream.

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>
Tested-by: Laura Abbott <labbott@redhat.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/arm64/include/asm/assembler.h | 19 +++++++++++++++----
arch/arm64/kernel/entry.S | 2 +-
2 files changed, 16 insertions(+), 5 deletions(-)

--- a/arch/arm64/include/asm/assembler.h
+++ b/arch/arm64/include/asm/assembler.h
@@ -239,14 +239,25 @@ 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

/*
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -243,7 +243,7 @@ alternative_insn eret, nop, ARM64_UNMAP_
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


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