From f97fc810798c261b2790c2a1660461a508a479e0 Mon Sep 17 00:00:00 2001 From: Steve Capper Date: Wed, 19 Nov 2014 16:53:43 +0000 Subject: [PATCH] arm64: percpu: Implement this_cpu operations The generic this_cpu operations disable interrupts to ensure that the requested operation is protected from pre-emption. For arm64, this is overkill and can hurt throughput and latency. This patch provides arm64 specific implementations for the this_cpu operations. Rather than disable interrupts, we use the exclusive monitor or atomic operations as appropriate. The following operations are implemented: add, add_return, and, or, read, write, xchg. We also wire up a cmpxchg implementation from cmpxchg.h. Testing was performed using the percpu_test module and hackbench on a Juno board running 3.18-rc4. Signed-off-by: Steve Capper Reviewed-by: Will Deacon Signed-off-by: Will Deacon --- arch/arm64/include/asm/cmpxchg.h | 6 +- arch/arm64/include/asm/percpu.h | 215 +++++++++++++++++++++++++++++++ 2 files changed, 219 insertions(+), 2 deletions(-) diff --git a/arch/arm64/include/asm/cmpxchg.h b/arch/arm64/include/asm/cmpxchg.h index 89e397befad5..cb9593079f29 100644 --- a/arch/arm64/include/asm/cmpxchg.h +++ b/arch/arm64/include/asm/cmpxchg.h @@ -246,8 +246,10 @@ static inline unsigned long __cmpxchg_mb(volatile void *ptr, unsigned long old, __ret; \ }) -#define this_cpu_cmpxchg_8(ptr, o, n) \ - cmpxchg_local(raw_cpu_ptr(&(ptr)), o, n) +#define this_cpu_cmpxchg_1(ptr, o, n) cmpxchg_local(raw_cpu_ptr(&(ptr)), o, n) +#define this_cpu_cmpxchg_2(ptr, o, n) cmpxchg_local(raw_cpu_ptr(&(ptr)), o, n) +#define this_cpu_cmpxchg_4(ptr, o, n) cmpxchg_local(raw_cpu_ptr(&(ptr)), o, n) +#define this_cpu_cmpxchg_8(ptr, o, n) cmpxchg_local(raw_cpu_ptr(&(ptr)), o, n) #define this_cpu_cmpxchg_double_8(ptr1, ptr2, o1, o2, n1, n2) \ cmpxchg_double_local(raw_cpu_ptr(&(ptr1)), raw_cpu_ptr(&(ptr2)), \ diff --git a/arch/arm64/include/asm/percpu.h b/arch/arm64/include/asm/percpu.h index 5279e5733386..09da25bc596f 100644 --- a/arch/arm64/include/asm/percpu.h +++ b/arch/arm64/include/asm/percpu.h @@ -44,6 +44,221 @@ static inline unsigned long __my_cpu_offset(void) #endif /* CONFIG_SMP */ +#define PERCPU_OP(op, asm_op) \ +static inline unsigned long __percpu_##op(void *ptr, \ + unsigned long val, int size) \ +{ \ + unsigned long loop, ret; \ + \ + switch (size) { \ + case 1: \ + do { \ + asm ("//__per_cpu_" #op "_1\n" \ + "ldxrb %w[ret], %[ptr]\n" \ + #asm_op " %w[ret], %w[ret], %w[val]\n" \ + "stxrb %w[loop], %w[ret], %[ptr]\n" \ + : [loop] "=&r" (loop), [ret] "=&r" (ret), \ + [ptr] "+Q"(*(u8 *)ptr) \ + : [val] "Ir" (val)); \ + } while (loop); \ + break; \ + case 2: \ + do { \ + asm ("//__per_cpu_" #op "_2\n" \ + "ldxrh %w[ret], %[ptr]\n" \ + #asm_op " %w[ret], %w[ret], %w[val]\n" \ + "stxrh %w[loop], %w[ret], %[ptr]\n" \ + : [loop] "=&r" (loop), [ret] "=&r" (ret), \ + [ptr] "+Q"(*(u16 *)ptr) \ + : [val] "Ir" (val)); \ + } while (loop); \ + break; \ + case 4: \ + do { \ + asm ("//__per_cpu_" #op "_4\n" \ + "ldxr %w[ret], %[ptr]\n" \ + #asm_op " %w[ret], %w[ret], %w[val]\n" \ + "stxr %w[loop], %w[ret], %[ptr]\n" \ + : [loop] "=&r" (loop), [ret] "=&r" (ret), \ + [ptr] "+Q"(*(u32 *)ptr) \ + : [val] "Ir" (val)); \ + } while (loop); \ + break; \ + case 8: \ + do { \ + asm ("//__per_cpu_" #op "_8\n" \ + "ldxr %[ret], %[ptr]\n" \ + #asm_op " %[ret], %[ret], %[val]\n" \ + "stxr %w[loop], %[ret], %[ptr]\n" \ + : [loop] "=&r" (loop), [ret] "=&r" (ret), \ + [ptr] "+Q"(*(u64 *)ptr) \ + : [val] "Ir" (val)); \ + } while (loop); \ + break; \ + default: \ + BUILD_BUG(); \ + } \ + \ + return ret; \ +} + +PERCPU_OP(add, add) +PERCPU_OP(and, and) +PERCPU_OP(or, orr) +#undef PERCPU_OP + +static inline unsigned long __percpu_read(void *ptr, int size) +{ + unsigned long ret; + + switch (size) { + case 1: + ret = ACCESS_ONCE(*(u8 *)ptr); + break; + case 2: + ret = ACCESS_ONCE(*(u16 *)ptr); + break; + case 4: + ret = ACCESS_ONCE(*(u32 *)ptr); + break; + case 8: + ret = ACCESS_ONCE(*(u64 *)ptr); + break; + default: + BUILD_BUG(); + } + + return ret; +} + +static inline void __percpu_write(void *ptr, unsigned long val, int size) +{ + switch (size) { + case 1: + ACCESS_ONCE(*(u8 *)ptr) = (u8)val; + break; + case 2: + ACCESS_ONCE(*(u16 *)ptr) = (u16)val; + break; + case 4: + ACCESS_ONCE(*(u32 *)ptr) = (u32)val; + break; + case 8: + ACCESS_ONCE(*(u64 *)ptr) = (u64)val; + break; + default: + BUILD_BUG(); + } +} + +static inline unsigned long __percpu_xchg(void *ptr, unsigned long val, + int size) +{ + unsigned long ret, loop; + + switch (size) { + case 1: + do { + asm ("//__percpu_xchg_1\n" + "ldxrb %w[ret], %[ptr]\n" + "stxrb %w[loop], %w[val], %[ptr]\n" + : [loop] "=&r"(loop), [ret] "=&r"(ret), + [ptr] "+Q"(*(u8 *)ptr) + : [val] "r" (val)); + } while (loop); + break; + case 2: + do { + asm ("//__percpu_xchg_2\n" + "ldxrh %w[ret], %[ptr]\n" + "stxrh %w[loop], %w[val], %[ptr]\n" + : [loop] "=&r"(loop), [ret] "=&r"(ret), + [ptr] "+Q"(*(u16 *)ptr) + : [val] "r" (val)); + } while (loop); + break; + case 4: + do { + asm ("//__percpu_xchg_4\n" + "ldxr %w[ret], %[ptr]\n" + "stxr %w[loop], %w[val], %[ptr]\n" + : [loop] "=&r"(loop), [ret] "=&r"(ret), + [ptr] "+Q"(*(u32 *)ptr) + : [val] "r" (val)); + } while (loop); + break; + case 8: + do { + asm ("//__percpu_xchg_8\n" + "ldxr %[ret], %[ptr]\n" + "stxr %w[loop], %[val], %[ptr]\n" + : [loop] "=&r"(loop), [ret] "=&r"(ret), + [ptr] "+Q"(*(u64 *)ptr) + : [val] "r" (val)); + } while (loop); + break; + default: + BUILD_BUG(); + } + + return ret; +} + +#define _percpu_add(pcp, val) \ + __percpu_add(raw_cpu_ptr(&(pcp)), val, sizeof(pcp)) + +#define _percpu_add_return(pcp, val) (typeof(pcp)) (_percpu_add(pcp, val)) + +#define _percpu_and(pcp, val) \ + __percpu_and(raw_cpu_ptr(&(pcp)), val, sizeof(pcp)) + +#define _percpu_or(pcp, val) \ + __percpu_or(raw_cpu_ptr(&(pcp)), val, sizeof(pcp)) + +#define _percpu_read(pcp) (typeof(pcp)) \ + (__percpu_read(raw_cpu_ptr(&(pcp)), sizeof(pcp))) + +#define _percpu_write(pcp, val) \ + __percpu_write(raw_cpu_ptr(&(pcp)), (unsigned long)(val), sizeof(pcp)) + +#define _percpu_xchg(pcp, val) (typeof(pcp)) \ + (__percpu_xchg(raw_cpu_ptr(&(pcp)), (unsigned long)(val), sizeof(pcp))) + +#define this_cpu_add_1(pcp, val) _percpu_add(pcp, val) +#define this_cpu_add_2(pcp, val) _percpu_add(pcp, val) +#define this_cpu_add_4(pcp, val) _percpu_add(pcp, val) +#define this_cpu_add_8(pcp, val) _percpu_add(pcp, val) + +#define this_cpu_add_return_1(pcp, val) _percpu_add_return(pcp, val) +#define this_cpu_add_return_2(pcp, val) _percpu_add_return(pcp, val) +#define this_cpu_add_return_4(pcp, val) _percpu_add_return(pcp, val) +#define this_cpu_add_return_8(pcp, val) _percpu_add_return(pcp, val) + +#define this_cpu_and_1(pcp, val) _percpu_and(pcp, val) +#define this_cpu_and_2(pcp, val) _percpu_and(pcp, val) +#define this_cpu_and_4(pcp, val) _percpu_and(pcp, val) +#define this_cpu_and_8(pcp, val) _percpu_and(pcp, val) + +#define this_cpu_or_1(pcp, val) _percpu_or(pcp, val) +#define this_cpu_or_2(pcp, val) _percpu_or(pcp, val) +#define this_cpu_or_4(pcp, val) _percpu_or(pcp, val) +#define this_cpu_or_8(pcp, val) _percpu_or(pcp, val) + +#define this_cpu_read_1(pcp) _percpu_read(pcp) +#define this_cpu_read_2(pcp) _percpu_read(pcp) +#define this_cpu_read_4(pcp) _percpu_read(pcp) +#define this_cpu_read_8(pcp) _percpu_read(pcp) + +#define this_cpu_write_1(pcp, val) _percpu_write(pcp, val) +#define this_cpu_write_2(pcp, val) _percpu_write(pcp, val) +#define this_cpu_write_4(pcp, val) _percpu_write(pcp, val) +#define this_cpu_write_8(pcp, val) _percpu_write(pcp, val) + +#define this_cpu_xchg_1(pcp, val) _percpu_xchg(pcp, val) +#define this_cpu_xchg_2(pcp, val) _percpu_xchg(pcp, val) +#define this_cpu_xchg_4(pcp, val) _percpu_xchg(pcp, val) +#define this_cpu_xchg_8(pcp, val) _percpu_xchg(pcp, val) + #include #endif /* __ASM_PERCPU_H */ -- 2.30.2