From: Christophe Leroy <christophe.leroy@c-s.fr>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Michael Ellerman <mpe@ellerman.id.au>
Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: [RFC PATCH 2/8] powerpc/irq: inline call_do_irq() and call_do_softirq() on PPC32
Date: Mon, 23 Dec 2019 15:26:12 +0000 (UTC) [thread overview]
Message-ID: <075b56d1ef9ff0556916684029e8006123a1ca09.1577114567.git.christophe.leroy@c-s.fr> (raw)
In-Reply-To: <cover.1577114567.git.christophe.leroy@c-s.fr>
call_do_irq() and call_do_softirq() are simple enough to be
worth inlining.
Inlining them avoids an mflr/mtlr pair plus a save/reload on stack.
It also allows GCC to keep the saved ksp_limit in an nonvolatile reg.
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
v5:
- Limiting the change to PPC32 for now.
- removed r2 from the clobbered regs list (on PPC32 r2 points to current all the time)
- Removed patch 1 and merged ksp_limit handling in here.
v6:
- rebased after removal of ksp_limit
---
arch/powerpc/include/asm/irq.h | 2 ++
arch/powerpc/kernel/irq.c | 34 ++++++++++++++++++++++++++++++++++
arch/powerpc/kernel/misc_32.S | 25 -------------------------
3 files changed, 36 insertions(+), 25 deletions(-)
diff --git a/arch/powerpc/include/asm/irq.h b/arch/powerpc/include/asm/irq.h
index 814dfab7e392..e4a92f0b4ad4 100644
--- a/arch/powerpc/include/asm/irq.h
+++ b/arch/powerpc/include/asm/irq.h
@@ -56,8 +56,10 @@ extern void *mcheckirq_ctx[NR_CPUS];
extern void *hardirq_ctx[NR_CPUS];
extern void *softirq_ctx[NR_CPUS];
+#ifdef CONFIG_PPC64
void call_do_softirq(void *sp);
void call_do_irq(struct pt_regs *regs, void *sp);
+#endif
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 add67498c126..4690e5270806 100644
--- a/arch/powerpc/kernel/irq.c
+++ b/arch/powerpc/kernel/irq.c
@@ -611,6 +611,40 @@ static inline void check_stack_overflow(void)
#endif
}
+#ifdef CONFIG_PPC32
+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", "r4", "r5", "r6", "r7", "r8", "r9", "r10", "r11", "r12");
+}
+
+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", "r4", "r5", "r6", "r7", "r8", "r9", "r10", "r11", "r12");
+}
+#endif
+
void __do_irq(struct pt_regs *regs)
{
unsigned int irq;
diff --git a/arch/powerpc/kernel/misc_32.S b/arch/powerpc/kernel/misc_32.S
index bb5995fa6884..341a3cd199cb 100644
--- a/arch/powerpc/kernel/misc_32.S
+++ b/arch/powerpc/kernel/misc_32.S
@@ -27,31 +27,6 @@
.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.
*/
--
2.13.3
next prev parent reply other threads:[~2019-12-23 15:26 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-23 15:26 [RFC PATCH 0/8] Accelarate IRQ entry Christophe Leroy
2019-12-23 15:26 ` [RFC PATCH 1/8] powerpc/32: drop ksp_limit based stack overflow detection Christophe Leroy
2019-12-23 15:26 ` Christophe Leroy [this message]
2019-12-23 15:26 ` [RFC PATCH 3/8] powerpc/irq: don't use current_stack_pointer() in do_IRQ() Christophe Leroy
2019-12-23 15:26 ` [RFC PATCH 4/8] powerpc/irq: move set_irq_regs() closer to irq_enter/exit() Christophe Leroy
2019-12-23 15:26 ` [RFC PATCH 5/8] powerpc/irq: move stack overflow verification Christophe Leroy
2019-12-23 15:26 ` [RFC PATCH 6/8] powerpc/irq: cleanup check_stack_overflow() a bit Christophe Leroy
2019-12-23 15:26 ` [RFC PATCH 7/8] powerpc/32: use IRQ stack immediately on IRQ exception Christophe Leroy
2019-12-23 15:26 ` [RFC PATCH 8/8] powerpc/irq: drop softirq stack Christophe Leroy
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