Re: [PATCH] powerpc/64s: power4 nap fixup in C
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: 2021-03-29 08:35:50
On Fri, 2021-03-12 at 11:20 +1000, Nicholas Piggin wrote:
+static inline void nap_adjust_return(struct pt_regs *regs)
+{
+#ifdef CONFIG_PPC_970_NAP
+ if (unlikely(test_thread_local_flags(_TLF_NAPPING))) {
+ /* Can avoid a test-and-clear because NMIs do not call this */
+ clear_thread_local_flags(_TLF_NAPPING);
+ regs->nip = (unsigned long)power4_idle_nap_return;
+ }Is this a pointer to a function descriptor or the actual code ? Cheers, Ben.
quoted hunk ↗ jump to hunk
+#endif +} + struct interrupt_state { #ifdef CONFIG_PPC_BOOK3E_64 enum ctx_state ctx_state;@@ -111,6 +122,9 @@ static inline void interrupt_async_exit_prepare(struct pt_regs *regs, struct int { irq_exit(); interrupt_exit_prepare(regs, state); + + /* Adjust at exit so the main handler sees the true NIA */ + nap_adjust_return(regs); } struct interrupt_nmi_state {@@ -164,6 +178,11 @@ static inline void interrupt_nmi_exit_prepare(struct pt_regs *regs, struct inter radix_enabled() || (mfmsr() & MSR_DR)) nmi_exit(); + /* + * nmi does not call nap_adjust_return because nmi should not create + * new work to do (must use irq_work for that). + */ + #ifdef CONFIG_PPC64 if (TRAP(regs) != 0x900 && TRAP(regs) != 0xf00 && TRAP(regs) != 0x260) this_cpu_set_ftrace_enabled(state->ftrace_enabled);diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h index 8acc3590c971..eedc3c775141 100644 --- a/arch/powerpc/include/asm/processor.h +++ b/arch/powerpc/include/asm/processor.h@@ -393,6 +393,7 @@ extern unsigned long isa300_idle_stop_mayloss(unsigned long psscr_val); extern unsigned long isa206_idle_insn_mayloss(unsigned long type); #ifdef CONFIG_PPC_970_NAP extern void power4_idle_nap(void); +void power4_idle_nap_return(void); #endif extern unsigned long cpuidle_disable;diff --git a/arch/powerpc/include/asm/thread_info.h b/arch/powerpc/include/asm/thread_info.h index 386d576673a1..bf137151100b 100644 --- a/arch/powerpc/include/asm/thread_info.h +++ b/arch/powerpc/include/asm/thread_info.h@@ -152,6 +152,12 @@ void arch_setup_new_exec(void); #ifndef __ASSEMBLY__ +static inline void clear_thread_local_flags(unsigned int flags) +{ + struct thread_info *ti = current_thread_info(); + ti->local_flags &= ~flags; +} + static inline bool test_thread_local_flags(unsigned int flags) { struct thread_info *ti = current_thread_info();diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S index 60d3051a8bc8..ea7a443488d2 100644 --- a/arch/powerpc/kernel/exceptions-64s.S +++ b/arch/powerpc/kernel/exceptions-64s.S@@ -692,25 +692,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_CFAR) ld r1,GPR1(r1) .endm -/* - * When the idle code in power4_idle puts the CPU into NAP mode, - * it has to do so in a loop, and relies on the external interrupt - * and decrementer interrupt entry code to get it out of the loop. - * It sets the _TLF_NAPPING bit in current_thread_info()->local_flags - * to signal that it is in the loop and needs help to get out. - */ -#ifdef CONFIG_PPC_970_NAP -#define FINISH_NAP \ -BEGIN_FTR_SECTION \ - ld r11, PACA_THREAD_INFO(r13); \ - ld r9,TI_LOCAL_FLAGS(r11); \ - andi. r10,r9,_TLF_NAPPING; \ - bnel power4_fixup_nap; \ -END_FTR_SECTION_IFSET(CPU_FTR_CAN_NAP) -#else -#define FINISH_NAP -#endif - /* * There are a few constraints to be concerned with. * - Real mode exceptions code/data must be located at their physical location.@@ -1248,7 +1229,6 @@ EXC_COMMON_BEGIN(machine_check_common) */ GEN_COMMON machine_check - FINISH_NAP /* Enable MSR_RI when finished with PACA_EXMC */ li r10,MSR_RI mtmsrd r10,1@@ -1571,7 +1551,6 @@ EXC_VIRT_BEGIN(hardware_interrupt, 0x4500, 0x100) EXC_VIRT_END(hardware_interrupt, 0x4500, 0x100) EXC_COMMON_BEGIN(hardware_interrupt_common) GEN_COMMON hardware_interrupt - FINISH_NAP addi r3,r1,STACK_FRAME_OVERHEAD bl do_IRQ b interrupt_return@@ -1801,7 +1780,6 @@ EXC_VIRT_BEGIN(decrementer, 0x4900, 0x80) EXC_VIRT_END(decrementer, 0x4900, 0x80) EXC_COMMON_BEGIN(decrementer_common) GEN_COMMON decrementer - FINISH_NAP addi r3,r1,STACK_FRAME_OVERHEAD bl timer_interrupt b interrupt_return@@ -1886,7 +1864,6 @@ EXC_VIRT_BEGIN(doorbell_super, 0x4a00, 0x100) EXC_VIRT_END(doorbell_super, 0x4a00, 0x100) EXC_COMMON_BEGIN(doorbell_super_common) GEN_COMMON doorbell_super - FINISH_NAP addi r3,r1,STACK_FRAME_OVERHEAD #ifdef CONFIG_PPC_DOORBELL bl doorbell_exception@@ -2237,7 +2214,6 @@ EXC_COMMON_BEGIN(hmi_exception_early_common) EXC_COMMON_BEGIN(hmi_exception_common) GEN_COMMON hmi_exception - FINISH_NAP addi r3,r1,STACK_FRAME_OVERHEAD bl handle_hmi_exception b interrupt_return@@ -2266,7 +2242,6 @@ EXC_VIRT_BEGIN(h_doorbell, 0x4e80, 0x20) EXC_VIRT_END(h_doorbell, 0x4e80, 0x20) EXC_COMMON_BEGIN(h_doorbell_common) GEN_COMMON h_doorbell - FINISH_NAP addi r3,r1,STACK_FRAME_OVERHEAD #ifdef CONFIG_PPC_DOORBELL bl doorbell_exception@@ -2299,7 +2274,6 @@ EXC_VIRT_BEGIN(h_virt_irq, 0x4ea0, 0x20) EXC_VIRT_END(h_virt_irq, 0x4ea0, 0x20) EXC_COMMON_BEGIN(h_virt_irq_common) GEN_COMMON h_virt_irq - FINISH_NAP addi r3,r1,STACK_FRAME_OVERHEAD bl do_IRQ b interrupt_return@@ -2345,7 +2319,6 @@ EXC_VIRT_BEGIN(performance_monitor, 0x4f00, 0x20) EXC_VIRT_END(performance_monitor, 0x4f00, 0x20) EXC_COMMON_BEGIN(performance_monitor_common) GEN_COMMON performance_monitor - FINISH_NAP addi r3,r1,STACK_FRAME_OVERHEAD bl performance_monitor_exception b interrupt_return@@ -3096,24 +3069,6 @@ USE_FIXED_SECTION(virt_trampolines) __end_interrupts: DEFINE_FIXED_SYMBOL(__end_interrupts) -#ifdef CONFIG_PPC_970_NAP - /* - * Called by exception entry code if _TLF_NAPPING was set, this clears - * the NAPPING flag, and redirects the exception exit to - * power4_fixup_nap_return. - */ - .globl power4_fixup_nap -EXC_COMMON_BEGIN(power4_fixup_nap) - andc r9,r9,r10 - std r9,TI_LOCAL_FLAGS(r11) - LOAD_REG_ADDR(r10, power4_idle_nap_return) - std r10,_NIP(r1) - blr - -power4_idle_nap_return: - blr -#endif - CLOSE_FIXED_SECTION(real_vectors); CLOSE_FIXED_SECTION(real_trampolines); CLOSE_FIXED_SECTION(virt_vectors);diff --git a/arch/powerpc/kernel/idle_book3s.S b/arch/powerpc/kernel/idle_book3s.S index f9e6d83e6720..abb719b21cae 100644 --- a/arch/powerpc/kernel/idle_book3s.S +++ b/arch/powerpc/kernel/idle_book3s.S@@ -209,4 +209,8 @@ _GLOBAL(power4_idle_nap) mtmsrd r7 isync b 1b + + .globl power4_idle_nap_return +power4_idle_nap_return: + blr #endif --2.23.0