powerpc/book3e: Add generic 64-bit idle powersave
PATCH v2 1/1 powerpc/book3e: Add generic 64-bit idle powersave
We use a similar technique to ppc32: We set a thread local flag to indicate that we are about to enter or have entered the stop state, and have fixup code in the async interrupt entry code that reacts to this flag to make us return to a different location (sets NIP to LINK in our case).
Signed-off-by Benjamin Herrenschmidt <[email protected]>
--
v2. Fix lockdep bug
Re-mask interrupts when coming back from idle
--- arch/powerpc/include/asm/machdep.h | 1 + arch/powerpc/kernel/Makefile | 2 +- arch/powerpc/kernel/exceptions-64e.S | 23 +++++++++ arch/powerpc/kernel/idle_book3e.S | 86 ++++++++++++++++++++++++++++++++++ 4 files changed, 111 insertions(+), 1 deletions(-) create mode 100644 arch/powerpc/kernel/idle_book3e.S
arch/powerpc/include/asm/machdep.h +1 -0
@@ -278,6 +278,7 @@ extern void e500_idle(void);extern void power4_idle (void );extern void power4_cpu_offline_powersave (void );extern void ppc6xx_idle (void ); +extern void book3e_idle (void );/* * ppc_md contains a copy of the machine description structure for the
arch/powerpc/kernel/Makefile +1 -1
@@ -37,7 +37,7 @@ obj-$(CONFIG_PPC64) += setup_64.o sys_ppc32.o \ obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o obj-$(CONFIG_PPC_BOOK3S_64) += cpu_setup_ppc970.o cpu_setup_pa6t.o obj64-$(CONFIG_RELOCATABLE) += reloc_64.o -obj-$(CONFIG_PPC_BOOK3E_64) += exceptions-64e.o +obj-$(CONFIG_PPC_BOOK3E_64) += exceptions-64e.o idle_book3e.o obj-$(CONFIG_PPC64) += vdso64/ obj-$(CONFIG_ALTIVEC) += vecemu.o obj-$(CONFIG_PPC_970_NAP) += idle_power4.o
arch/powerpc/kernel/exceptions-64e.S +23 -0
@@ -204,11 +204,30 @@ exc_##n##_bad_stack: \ lis r,TSR_FIS@h; \ mtspr SPRN_TSR,r +/* Used by asynchronous interrupt that may happen in the idle loop. + * + * This check if the thread was in the idle loop, and if yes, returns + * to the caller rather than the PC. This is to avoid a race if + * interrupts happen before the wait instruction. + */ +#define CHECK_NAPPING() \ + clrrdi r11,r1,THREAD_SHIFT; \ + ld r10,TI_LOCAL_FLAGS(r11); \ + andi. r9,r10,_TLF_NAPPING; \ + beq+ 1f; \ + ld r8,_LINK(r1); \ + rlwinm r7,r10,0,~_TLF_NAPPING; \ + std r8,_NIP(r1); \ + std r7,TI_LOCAL_FLAGS(r11); \ +1: + + #define MASKABLE_EXCEPTION(trapnum, label, hdlr, ack) \ START_EXCEPTION(label); \ NORMAL_EXCEPTION_PROLOG(trapnum, PROLOG_ADDITION_MASKABLE) \ EXCEPTION_COMMON(trapnum, PACA_EXGEN, INTS_DISABLE_ALL) \ ack(r8); \ + CHECK_NAPPING(); \ addi r3,r1,STACK_FRAME_OVERHEAD; \ bl hdlr; \ b .ret_from_except_lite;
@@ -257,6 +276,7 @@ interrupt_end_book3e: CRIT_EXCEPTION_PROLOG(0x100, PROLOG_ADDITION_NONE) // EXCEPTION_COMMON(0x100, PACA_EXCRIT, INTS_DISABLE_ALL) // bl special_reg_save_crit +// CHECK_NAPPING(); // addi r3,r1,STACK_FRAME_OVERHEAD // bl .critical_exception // b ret_from_crit_except
@@ -268,6 +288,7 @@ interrupt_end_book3e: // EXCEPTION_COMMON(0x200, PACA_EXMC, INTS_DISABLE_ALL) // bl special_reg_save_mc // addi r3,r1,STACK_FRAME_OVERHEAD +// CHECK_NAPPING(); // bl .machine_check_exception // b ret_from_mc_except b .
@@ -338,6 +359,7 @@ interrupt_end_book3e: CRIT_EXCEPTION_PROLOG(0x9f0, PROLOG_ADDITION_NONE) // EXCEPTION_COMMON(0x9f0, PACA_EXCRIT, INTS_DISABLE_ALL) // bl special_reg_save_crit +// CHECK_NAPPING(); // addi r3,r1,STACK_FRAME_OVERHEAD // bl .unknown_exception // b ret_from_crit_except
@@ -434,6 +456,7 @@ kernel_dbg_exc: CRIT_EXCEPTION_PROLOG(0x2080, PROLOG_ADDITION_NONE) // EXCEPTION_COMMON(0x2080, PACA_EXCRIT, INTS_DISABLE_ALL) // bl special_reg_save_crit +// CHECK_NAPPING(); // addi r3,r1,STACK_FRAME_OVERHEAD // bl .doorbell_critical_exception // b ret_from_crit_except
arch/powerpc/kernel/idle_book3e.S new file +86 -0
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