From 18ad51dd342a7eb09dbcd059d0b451b616d4dafc Mon Sep 17 00:00:00 2001 From: Anton Blanchard Date: Wed, 4 Jul 2012 20:37:11 +0000 Subject: [PATCH] powerpc: Add VDSO version of getcpu We have a request for a fast method of getting CPU and NUMA node IDs from userspace. This patch implements a getcpu VDSO function, similar to x86. Ben suggested we use SPRG3 which is userspace readable. SPRG3 can be modified by a KVM guest, so we save the SPRG3 value in the paca and restore it when transitioning from the guest to the host. I have a glibc patch that implements sched_getcpu on top of this. Testing on a POWER7: baseline: 538 cycles vdso: 30 cycles Signed-off-by: Anton Blanchard Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/include/asm/kvm_book3s_asm.h | 1 + arch/powerpc/include/asm/reg.h | 5 ++-- arch/powerpc/include/asm/vdso.h | 2 ++ arch/powerpc/kernel/asm-offsets.c | 1 + arch/powerpc/kernel/smp.c | 3 +++ arch/powerpc/kernel/vdso.c | 28 +++++++++++++++++++ arch/powerpc/kernel/vdso32/Makefile | 4 ++- arch/powerpc/kernel/vdso32/getcpu.S | 45 +++++++++++++++++++++++++++++++ arch/powerpc/kernel/vdso32/vdso32.lds.S | 3 +++ arch/powerpc/kernel/vdso64/Makefile | 2 +- arch/powerpc/kernel/vdso64/getcpu.S | 45 +++++++++++++++++++++++++++++++ arch/powerpc/kernel/vdso64/vdso64.lds.S | 1 + arch/powerpc/kvm/book3s_hv_rmhandlers.S | 4 +++ 13 files changed, 140 insertions(+), 4 deletions(-) create mode 100644 arch/powerpc/kernel/vdso32/getcpu.S create mode 100644 arch/powerpc/kernel/vdso64/getcpu.S diff --git a/arch/powerpc/include/asm/kvm_book3s_asm.h b/arch/powerpc/include/asm/kvm_book3s_asm.h index 88609b2..bfcd00c 100644 --- a/arch/powerpc/include/asm/kvm_book3s_asm.h +++ b/arch/powerpc/include/asm/kvm_book3s_asm.h @@ -74,6 +74,7 @@ struct kvmppc_host_state { ulong vmhandler; ulong scratch0; ulong scratch1; + ulong sprg3; u8 in_guest; u8 restore_hid5; u8 napping; diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h index f0cb7f4..2baeb7c 100644 --- a/arch/powerpc/include/asm/reg.h +++ b/arch/powerpc/include/asm/reg.h @@ -491,6 +491,7 @@ #define SPRN_SPRG1 0x111 /* Special Purpose Register General 1 */ #define SPRN_SPRG2 0x112 /* Special Purpose Register General 2 */ #define SPRN_SPRG3 0x113 /* Special Purpose Register General 3 */ +#define SPRN_USPRG3 0x103 /* SPRG3 userspace read */ #define SPRN_SPRG4 0x114 /* Special Purpose Register General 4 */ #define SPRN_SPRG5 0x115 /* Special Purpose Register General 5 */ #define SPRN_SPRG6 0x116 /* Special Purpose Register General 6 */ @@ -753,14 +754,14 @@ * 64-bit server: * - SPRG0 unused (reserved for HV on Power4) * - SPRG2 scratch for exception vectors - * - SPRG3 unused (user visible) + * - SPRG3 CPU and NUMA node for VDSO getcpu (user visible) * - HSPRG0 stores PACA in HV mode * - HSPRG1 scratch for "HV" exceptions * * 64-bit embedded * - SPRG0 generic exception scratch * - SPRG2 TLB exception stack - * - SPRG3 unused (user visible) + * - SPRG3 CPU and NUMA node for VDSO getcpu (user visible) * - SPRG4 unused (user visible) * - SPRG6 TLB miss scratch (user visible, sorry !) * - SPRG7 critical exception scratch diff --git a/arch/powerpc/include/asm/vdso.h b/arch/powerpc/include/asm/vdso.h index dc0419b..50f261b 100644 --- a/arch/powerpc/include/asm/vdso.h +++ b/arch/powerpc/include/asm/vdso.h @@ -22,6 +22,8 @@ extern unsigned long vdso64_rt_sigtramp; extern unsigned long vdso32_sigtramp; extern unsigned long vdso32_rt_sigtramp; +int __cpuinit vdso_getcpu_init(void); + #else /* __ASSEMBLY__ */ #ifdef __VDSO64__ diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c index 52c7ad7..85b05c4 100644 --- a/arch/powerpc/kernel/asm-offsets.c +++ b/arch/powerpc/kernel/asm-offsets.c @@ -533,6 +533,7 @@ int main(void) HSTATE_FIELD(HSTATE_VMHANDLER, vmhandler); HSTATE_FIELD(HSTATE_SCRATCH0, scratch0); HSTATE_FIELD(HSTATE_SCRATCH1, scratch1); + HSTATE_FIELD(HSTATE_SPRG3, sprg3); HSTATE_FIELD(HSTATE_IN_GUEST, in_guest); HSTATE_FIELD(HSTATE_RESTORE_HID5, restore_hid5); HSTATE_FIELD(HSTATE_NAPPING, napping); diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c index e1417c4..0321007 100644 --- a/arch/powerpc/kernel/smp.c +++ b/arch/powerpc/kernel/smp.c @@ -48,6 +48,7 @@ #ifdef CONFIG_PPC64 #include #endif +#include #include #ifdef DEBUG @@ -570,6 +571,8 @@ void __devinit start_secondary(void *unused) #ifdef CONFIG_PPC64 if (system_state == SYSTEM_RUNNING) vdso_data->processorCount++; + + vdso_getcpu_init(); #endif notify_cpu_starting(cpu); set_cpu_online(cpu, true); diff --git a/arch/powerpc/kernel/vdso.c b/arch/powerpc/kernel/vdso.c index 9eb5b9b..b67db22 100644 --- a/arch/powerpc/kernel/vdso.c +++ b/arch/powerpc/kernel/vdso.c @@ -706,6 +706,34 @@ static void __init vdso_setup_syscall_map(void) } } +#ifdef CONFIG_PPC64 +int __cpuinit vdso_getcpu_init(void) +{ + unsigned long cpu, node, val; + + /* + * SPRG3 contains the CPU in the bottom 16 bits and the NUMA node in + * the next 16 bits. The VDSO uses this to implement getcpu(). + */ + cpu = get_cpu(); + WARN_ON_ONCE(cpu > 0xffff); + + node = cpu_to_node(cpu); + WARN_ON_ONCE(node > 0xffff); + + val = (cpu & 0xfff) | ((node & 0xffff) << 16); + mtspr(SPRN_SPRG3, val); +#ifdef CONFIG_KVM_BOOK3S_HANDLER + get_paca()->kvm_hstate.sprg3 = val; +#endif + + put_cpu(); + + return 0; +} +/* We need to call this before SMP init */ +early_initcall(vdso_getcpu_init); +#endif static int __init vdso_init(void) { diff --git a/arch/powerpc/kernel/vdso32/Makefile b/arch/powerpc/kernel/vdso32/Makefile index 9a7946c..53e6c9b 100644 --- a/arch/powerpc/kernel/vdso32/Makefile +++ b/arch/powerpc/kernel/vdso32/Makefile @@ -1,7 +1,9 @@ # List of files in the vdso, has to be asm only for now -obj-vdso32 = sigtramp.o gettimeofday.o datapage.o cacheflush.o note.o +obj-vdso32-$(CONFIG_PPC64) = getcpu.o +obj-vdso32 = sigtramp.o gettimeofday.o datapage.o cacheflush.o note.o \ + $(obj-vdso32-y) # Build rules diff --git a/arch/powerpc/kernel/vdso32/getcpu.S b/arch/powerpc/kernel/vdso32/getcpu.S new file mode 100644 index 0000000..47afd08 --- /dev/null +++ b/arch/powerpc/kernel/vdso32/getcpu.S @@ -0,0 +1,45 @@ +/* + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + * + * Copyright (C) IBM Corporation, 2012 + * + * Author: Anton Blanchard + */ +#include +#include + + .text +/* + * Exact prototype of getcpu + * + * int __kernel_getcpu(unsigned *cpu, unsigned *node); + * + */ +V_FUNCTION_BEGIN(__kernel_getcpu) + .cfi_startproc + mfspr r5,SPRN_USPRG3 + cmpdi cr0,r3,0 + cmpdi cr1,r4,0 + clrlwi r6,r5,16 + rlwinm r7,r5,16,31-15,31-0 + beq cr0,1f + stw r6,0(r3) +1: beq cr1,2f + stw r7,0(r4) +2: crclr cr0*4+so + li r3,0 /* always success */ + blr + .cfi_endproc +V_FUNCTION_END(__kernel_getcpu) diff --git a/arch/powerpc/kernel/vdso32/vdso32.lds.S b/arch/powerpc/kernel/vdso32/vdso32.lds.S index 0546bcd..43200ba 100644 --- a/arch/powerpc/kernel/vdso32/vdso32.lds.S +++ b/arch/powerpc/kernel/vdso32/vdso32.lds.S @@ -147,6 +147,9 @@ VERSION __kernel_sync_dicache_p5; __kernel_sigtramp32; __kernel_sigtramp_rt32; +#ifdef CONFIG_PPC64 + __kernel_getcpu; +#endif local: *; }; diff --git a/arch/powerpc/kernel/vdso64/Makefile b/arch/powerpc/kernel/vdso64/Makefile index 8c500d8..effca94 100644 --- a/arch/powerpc/kernel/vdso64/Makefile +++ b/arch/powerpc/kernel/vdso64/Makefile @@ -1,6 +1,6 @@ # List of files in the vdso, has to be asm only for now -obj-vdso64 = sigtramp.o gettimeofday.o datapage.o cacheflush.o note.o +obj-vdso64 = sigtramp.o gettimeofday.o datapage.o cacheflush.o note.o getcpu.o # Build rules diff --git a/arch/powerpc/kernel/vdso64/getcpu.S b/arch/powerpc/kernel/vdso64/getcpu.S new file mode 100644 index 0000000..47afd08 --- /dev/null +++ b/arch/powerpc/kernel/vdso64/getcpu.S @@ -0,0 +1,45 @@ +/* + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + * + * Copyright (C) IBM Corporation, 2012 + * + * Author: Anton Blanchard + */ +#include +#include + + .text +/* + * Exact prototype of getcpu + * + * int __kernel_getcpu(unsigned *cpu, unsigned *node); + * + */ +V_FUNCTION_BEGIN(__kernel_getcpu) + .cfi_startproc + mfspr r5,SPRN_USPRG3 + cmpdi cr0,r3,0 + cmpdi cr1,r4,0 + clrlwi r6,r5,16 + rlwinm r7,r5,16,31-15,31-0 + beq cr0,1f + stw r6,0(r3) +1: beq cr1,2f + stw r7,0(r4) +2: crclr cr0*4+so + li r3,0 /* always success */ + blr + .cfi_endproc +V_FUNCTION_END(__kernel_getcpu) diff --git a/arch/powerpc/kernel/vdso64/vdso64.lds.S b/arch/powerpc/kernel/vdso64/vdso64.lds.S index 0e61540..e6c1758 100644 --- a/arch/powerpc/kernel/vdso64/vdso64.lds.S +++ b/arch/powerpc/kernel/vdso64/vdso64.lds.S @@ -146,6 +146,7 @@ VERSION __kernel_sync_dicache; __kernel_sync_dicache_p5; __kernel_sigtramp_rt64; + __kernel_getcpu; local: *; }; diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S index e764e23..5a84c8d 100644 --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S @@ -1064,6 +1064,10 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_206) mtspr SPRN_DABR,r5 mtspr SPRN_DABRX,r6 + /* Restore SPRG3 */ + ld r3,HSTATE_SPRG3(r13) + mtspr SPRN_SPRG3,r3 + /* * Reload DEC. HDEC interrupts were disabled when * we reloaded the host's LPCR value. -- 2.7.4