[PATCH v4 2/2] powerpc/irq: inline call_do_irq() and call_do_softirq()

Christophe Leroy
2019-10-10T05:36:37Z

call_do_irq() and call_do_softirq() are quite similar on PPC32 and
PPC64 and are simple enough to be worth inlining.

Inlining them avoids an mflr/mtlr pair plus a save/reload on stack.

This is inspired from S390 arch. Several other arches do more or
less the same. The way sparc arch does seems odd thought.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Segher Boessenkool <segher@kernel.crashing.org>

---
v2: no change.
v3: no change.
v4:
- comment reminding the purpose of the inline asm block.
- added r2 as clobbered reg
---
arch/powerpc/include/asm/irq.h | 2 --
arch/powerpc/kernel/irq.c | 32 ++++++++++++++++++++++++++++++++
arch/powerpc/kernel/misc_32.S | 25 -------------------------
arch/powerpc/kernel/misc_64.S | 22 ----------------------
4 files changed, 32 insertions(+), 49 deletions(-)

diff --git a/arch/powerpc/include/asm/irq.h b/arch/powerpc/include/asm/irq.h
index 0c6469983c66..10476d5283dc 100644
--- a/arch/powerpc/include/asm/irq.h
+++ b/arch/powerpc/include/asm/irq.h
@@ -57,8 +57,6 @@ extern void *mcheckirq_ctx[NR_CPUS];
extern void *hardirq_ctx[NR_CPUS];
extern void *softirq_ctx[NR_CPUS];

-void call_do_softirq(void *sp);
-void call_do_irq(struct pt_regs *regs, void *sp);
extern void do_IRQ(struct pt_regs *regs);
extern void __init init_IRQ(void);
extern void __do_irq(struct pt_regs *regs);
diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
index 04204be49577..d62fe18405a0 100644
--- a/arch/powerpc/kernel/irq.c
+++ b/arch/powerpc/kernel/irq.c
@@ -642,6 +642,22 @@ void __do_irq(struct pt_regs *regs)
irq_exit();
}

+static inline void call_do_irq(struct pt_regs *regs, void *sp)
+{
+ register unsigned long r3 asm("r3") = (unsigned long)regs;
+
+ /* Temporarily switch r1 to sp, call __do_irq() then restore r1 */
+ asm volatile(
+ " "PPC_STLU" 1, %2(%1);\n"
+ " mr 1, %1;\n"
+ " bl %3;\n"
+ " "PPC_LL" 1, 0(1);\n" :
+ "+r"(r3) :
+ "b"(sp), "i"(THREAD_SIZE - STACK_FRAME_OVERHEAD), "i"(__do_irq) :
+ "lr", "xer", "ctr", "memory", "cr0", "cr1", "cr5", "cr6", "cr7",
+ "r0", "r2", "r4", "r5", "r6", "r7", "r8", "r9", "r10", "r11", "r12");
+}
+
void do_IRQ(struct pt_regs *regs)
{
struct pt_regs *old_regs = set_irq_regs(regs);
@@ -686,6 +702,22 @@ void *mcheckirq_ctx[NR_CPUS] __read_mostly;
void *softirq_ctx[NR_CPUS] __read_mostly;
void *hardirq_ctx[NR_CPUS] __read_mostly;

+static inline void call_do_softirq(const void *sp)
+{
+ register unsigned long ret asm("r3");
+
+ /* Temporarily switch r1 to sp, call __do_softirq() then restore r1 */
+ asm volatile(
+ " "PPC_STLU" 1, %2(%1);\n"
+ " mr 1, %1;\n"
+ " bl %3;\n"
+ " "PPC_LL" 1, 0(1);\n" :
+ "=r"(ret) :
+ "b"(sp), "i"(THREAD_SIZE - STACK_FRAME_OVERHEAD), "i"(__do_softirq) :
+ "lr", "xer", "ctr", "memory", "cr0", "cr1", "cr5", "cr6", "cr7",
+ "r0", "r2", "r4", "r5", "r6", "r7", "r8", "r9", "r10", "r11", "r12");
+}
+
void do_softirq_own_stack(void)
{
void *irqsp = softirq_ctx[smp_processor_id()];
diff --git a/arch/powerpc/kernel/misc_32.S b/arch/powerpc/kernel/misc_32.S
index a5422f7782b3..307307b57743 100644
--- a/arch/powerpc/kernel/misc_32.S
+++ b/arch/powerpc/kernel/misc_32.S
@@ -33,31 +33,6 @@

.text

-_GLOBAL(call_do_softirq)
- mflr r0
- stw r0,4(r1)
- stwu r1,THREAD_SIZE-STACK_FRAME_OVERHEAD(r3)
- mr r1,r3
- bl __do_softirq
- lwz r1,0(r1)
- lwz r0,4(r1)
- mtlr r0
- blr
-
-/*
- * void call_do_irq(struct pt_regs *regs, void *sp);
- */
-_GLOBAL(call_do_irq)
- mflr r0
- stw r0,4(r1)
- stwu r1,THREAD_SIZE-STACK_FRAME_OVERHEAD(r4)
- mr r1,r4
- bl __do_irq
- lwz r1,0(r1)
- lwz r0,4(r1)
- mtlr r0
- blr
-
/*
* This returns the high 64 bits of the product of two 64-bit numbers.
*/
diff --git a/arch/powerpc/kernel/misc_64.S b/arch/powerpc/kernel/misc_64.S
index b55a7b4cb543..69fd714a5236 100644
--- a/arch/powerpc/kernel/misc_64.S
+++ b/arch/powerpc/kernel/misc_64.S
@@ -27,28 +27,6 @@

.text

-_GLOBAL(call_do_softirq)
- mflr r0
- std r0,16(r1)
- stdu r1,THREAD_SIZE-STACK_FRAME_OVERHEAD(r3)
- mr r1,r3
- bl __do_softirq
- ld r1,0(r1)
- ld r0,16(r1)
- mtlr r0
- blr
-
-_GLOBAL(call_do_irq)
- mflr r0
- std r0,16(r1)
- stdu r1,THREAD_SIZE-STACK_FRAME_OVERHEAD(r4)
- mr r1,r4
- bl __do_irq
- ld r1,0(r1)
- ld r0,16(r1)
- mtlr r0
- blr
-
.section ".toc","aw"
PPC64_CACHES:
.tc ppc64_caches[TC],ppc64_caches
--
2.13.3