From 11276d5306b8e5b438a36bbff855fe792d7eaa61 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Fri, 24 Jul 2015 15:09:55 +0200 Subject: locking/static_keys: Add a new static_key interface There are various problems and short-comings with the current static_key interface: - static_key_{true,false}() read like a branch depending on the key value, instead of the actual likely/unlikely branch depending on init value. - static_key_{true,false}() are, as stated above, tied to the static_key init values STATIC_KEY_INIT_{TRUE,FALSE}. - we're limited to the 2 (out of 4) possible options that compile to a default NOP because that's what our arch_static_branch() assembly emits. So provide a new static_key interface: DEFINE_STATIC_KEY_TRUE(name); DEFINE_STATIC_KEY_FALSE(name); Which define a key of different types with an initial true/false value. Then allow: static_branch_likely() static_branch_unlikely() to take a key of either type and emit the right instruction for the case. This means adding a second arch_static_branch_jump() assembly helper which emits a JMP per default. In order to determine the right instruction for the right state, encode the branch type in the LSB of jump_entry::key. This is the final step in removing the naming confusion that has led to a stream of avoidable bugs such as: a833581e372a ("x86, perf: Fix static_key bug in load_mm_cr4()") ... but it also allows new static key combinations that will give us performance enhancements in the subsequent patches. Tested-by: Rabin Vincent # arm Signed-off-by: Peter Zijlstra (Intel) Acked-by: Michael Ellerman # ppc Acked-by: Heiko Carstens # s390 Cc: Andrew Morton Cc: Linus Torvalds Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar --- arch/arm/include/asm/jump_label.h | 25 +++++++++++++++++-------- arch/arm64/include/asm/jump_label.h | 18 ++++++++++++++++-- arch/mips/include/asm/jump_label.h | 19 +++++++++++++++++-- arch/powerpc/include/asm/jump_label.h | 19 +++++++++++++++++-- arch/s390/include/asm/jump_label.h | 19 +++++++++++++++++-- arch/sparc/include/asm/jump_label.h | 35 ++++++++++++++++++++++++++--------- arch/x86/include/asm/jump_label.h | 21 +++++++++++++++++++-- 7 files changed, 129 insertions(+), 27 deletions(-) (limited to 'arch') diff --git a/arch/arm/include/asm/jump_label.h b/arch/arm/include/asm/jump_label.h index 5f337dc5c108..34f7b6980d21 100644 --- a/arch/arm/include/asm/jump_label.h +++ b/arch/arm/include/asm/jump_label.h @@ -4,23 +4,32 @@ #ifndef __ASSEMBLY__ #include +#include #define JUMP_LABEL_NOP_SIZE 4 -#ifdef CONFIG_THUMB2_KERNEL -#define JUMP_LABEL_NOP "nop.w" -#else -#define JUMP_LABEL_NOP "nop" -#endif +static __always_inline bool arch_static_branch(struct static_key *key, bool branch) +{ + asm_volatile_goto("1:\n\t" + WASM(nop) "\n\t" + ".pushsection __jump_table, \"aw\"\n\t" + ".word 1b, %l[l_yes], %c0\n\t" + ".popsection\n\t" + : : "i" (&((char *)key)[branch]) : : l_yes); + + return false; +l_yes: + return true; +} -static __always_inline bool arch_static_branch(struct static_key *key) +static __always_inline bool arch_static_branch_jump(struct static_key *key, bool branch) { asm_volatile_goto("1:\n\t" - JUMP_LABEL_NOP "\n\t" + WASM(b) " %l[l_yes]\n\t" ".pushsection __jump_table, \"aw\"\n\t" ".word 1b, %l[l_yes], %c0\n\t" ".popsection\n\t" - : : "i" (key) : : l_yes); + : : "i" (&((char *)key)[branch]) : : l_yes); return false; l_yes: diff --git a/arch/arm64/include/asm/jump_label.h b/arch/arm64/include/asm/jump_label.h index c0e5165c2f76..1b5e0e843c3a 100644 --- a/arch/arm64/include/asm/jump_label.h +++ b/arch/arm64/include/asm/jump_label.h @@ -26,14 +26,28 @@ #define JUMP_LABEL_NOP_SIZE AARCH64_INSN_SIZE -static __always_inline bool arch_static_branch(struct static_key *key) +static __always_inline bool arch_static_branch(struct static_key *key, bool branch) { asm goto("1: nop\n\t" ".pushsection __jump_table, \"aw\"\n\t" ".align 3\n\t" ".quad 1b, %l[l_yes], %c0\n\t" ".popsection\n\t" - : : "i"(key) : : l_yes); + : : "i"(&((char *)key)[branch]) : : l_yes); + + return false; +l_yes: + return true; +} + +static __always_inline bool arch_static_branch_jump(struct static_key *key, bool branch) +{ + asm goto("1: b %l[l_yes]\n\t" + ".pushsection __jump_table, \"aw\"\n\t" + ".align 3\n\t" + ".quad 1b, %l[l_yes], %c0\n\t" + ".popsection\n\t" + : : "i"(&((char *)key)[branch]) : : l_yes); return false; l_yes: diff --git a/arch/mips/include/asm/jump_label.h b/arch/mips/include/asm/jump_label.h index 608aa57799c8..e77672539e8e 100644 --- a/arch/mips/include/asm/jump_label.h +++ b/arch/mips/include/asm/jump_label.h @@ -26,14 +26,29 @@ #define NOP_INSN "nop" #endif -static __always_inline bool arch_static_branch(struct static_key *key) +static __always_inline bool arch_static_branch(struct static_key *key, bool branch) { asm_volatile_goto("1:\t" NOP_INSN "\n\t" "nop\n\t" ".pushsection __jump_table, \"aw\"\n\t" WORD_INSN " 1b, %l[l_yes], %0\n\t" ".popsection\n\t" - : : "i" (key) : : l_yes); + : : "i" (&((char *)key)[branch]) : : l_yes); + + return false; +l_yes: + return true; +} + +static __always_inline bool arch_static_branch_jump(struct static_key *key, bool branch) +{ + asm_volatile_goto("1:\tj %l[l_yes]\n\t" + "nop\n\t" + ".pushsection __jump_table, \"aw\"\n\t" + WORD_INSN " 1b, %l[l_yes], %0\n\t" + ".popsection\n\t" + : : "i" (&((char *)key)[branch]) : : l_yes); + return false; l_yes: return true; diff --git a/arch/powerpc/include/asm/jump_label.h b/arch/powerpc/include/asm/jump_label.h index efbf9a322a23..47e155f15433 100644 --- a/arch/powerpc/include/asm/jump_label.h +++ b/arch/powerpc/include/asm/jump_label.h @@ -18,14 +18,29 @@ #define JUMP_ENTRY_TYPE stringify_in_c(FTR_ENTRY_LONG) #define JUMP_LABEL_NOP_SIZE 4 -static __always_inline bool arch_static_branch(struct static_key *key) +static __always_inline bool arch_static_branch(struct static_key *key, bool branch) { asm_volatile_goto("1:\n\t" "nop\n\t" ".pushsection __jump_table, \"aw\"\n\t" JUMP_ENTRY_TYPE "1b, %l[l_yes], %c0\n\t" ".popsection \n\t" - : : "i" (key) : : l_yes); + : : "i" (&((char *)key)[branch]) : : l_yes); + + return false; +l_yes: + return true; +} + +static __always_inline bool arch_static_branch_jump(struct static_key *key, bool branch) +{ + asm_volatile_goto("1:\n\t" + "b %l[l_yes]\n\t" + ".pushsection __jump_table, \"aw\"\n\t" + JUMP_ENTRY_TYPE "1b, %l[l_yes], %c0\n\t" + ".popsection \n\t" + : : "i" (&((char *)key)[branch]) : : l_yes); + return false; l_yes: return true; diff --git a/arch/s390/include/asm/jump_label.h b/arch/s390/include/asm/jump_label.h index 69972b7957ee..7f9fd5e3f1bf 100644 --- a/arch/s390/include/asm/jump_label.h +++ b/arch/s390/include/asm/jump_label.h @@ -12,14 +12,29 @@ * We use a brcl 0,2 instruction for jump labels at compile time so it * can be easily distinguished from a hotpatch generated instruction. */ -static __always_inline bool arch_static_branch(struct static_key *key) +static __always_inline bool arch_static_branch(struct static_key *key, bool branch) { asm_volatile_goto("0: brcl 0,"__stringify(JUMP_LABEL_NOP_OFFSET)"\n" ".pushsection __jump_table, \"aw\"\n" ".balign 8\n" ".quad 0b, %l[label], %0\n" ".popsection\n" - : : "X" (key) : : label); + : : "X" (&((char *)key)[branch]) : : label); + + return false; +label: + return true; +} + +static __always_inline bool arch_static_branch_jump(struct static_key *key, bool branch) +{ + asm_volatile_goto("0: brcl 15, %l[label]\n" + ".pushsection __jump_table, \"aw\"\n" + ".balign 8\n" + ".quad 0b, %l[label], %0\n" + ".popsection\n" + : : "X" (&((char *)key)[branch]) : : label); + return false; label: return true; diff --git a/arch/sparc/include/asm/jump_label.h b/arch/sparc/include/asm/jump_label.h index cc9b04a2b11b..62d0354d1727 100644 --- a/arch/sparc/include/asm/jump_label.h +++ b/arch/sparc/include/asm/jump_label.h @@ -7,16 +7,33 @@ #define JUMP_LABEL_NOP_SIZE 4 -static __always_inline bool arch_static_branch(struct static_key *key) +static __always_inline bool arch_static_branch(struct static_key *key, bool branch) { - asm_volatile_goto("1:\n\t" - "nop\n\t" - "nop\n\t" - ".pushsection __jump_table, \"aw\"\n\t" - ".align 4\n\t" - ".word 1b, %l[l_yes], %c0\n\t" - ".popsection \n\t" - : : "i" (key) : : l_yes); + asm_volatile_goto("1:\n\t" + "nop\n\t" + "nop\n\t" + ".pushsection __jump_table, \"aw\"\n\t" + ".align 4\n\t" + ".word 1b, %l[l_yes], %c0\n\t" + ".popsection \n\t" + : : "i" (&((char *)key)[branch]) : : l_yes); + + return false; +l_yes: + return true; +} + +static __always_inline bool arch_static_branch_jump(struct static_key *key, bool branch) +{ + asm_volatile_goto("1:\n\t" + "b %l[l_yes]\n\t" + "nop\n\t" + ".pushsection __jump_table, \"aw\"\n\t" + ".align 4\n\t" + ".word 1b, %l[l_yes], %c0\n\t" + ".popsection \n\t" + : : "i" (&((char *)key)[branch]) : : l_yes); + return false; l_yes: return true; diff --git a/arch/x86/include/asm/jump_label.h b/arch/x86/include/asm/jump_label.h index a4c1cf7e93f8..28d7a857f9d1 100644 --- a/arch/x86/include/asm/jump_label.h +++ b/arch/x86/include/asm/jump_label.h @@ -16,7 +16,7 @@ # define STATIC_KEY_INIT_NOP GENERIC_NOP5_ATOMIC #endif -static __always_inline bool arch_static_branch(struct static_key *key) +static __always_inline bool arch_static_branch(struct static_key *key, bool branch) { asm_volatile_goto("1:" ".byte " __stringify(STATIC_KEY_INIT_NOP) "\n\t" @@ -24,7 +24,24 @@ static __always_inline bool arch_static_branch(struct static_key *key) _ASM_ALIGN "\n\t" _ASM_PTR "1b, %l[l_yes], %c0 \n\t" ".popsection \n\t" - : : "i" (key) : : l_yes); + : : "i" (&((char *)key)[branch]) : : l_yes); + + return false; +l_yes: + return true; +} + +static __always_inline bool arch_static_branch_jump(struct static_key *key, bool branch) +{ + asm_volatile_goto("1:" + ".byte 0xe9\n\t .long %l[l_yes] - 2f\n\t" + "2:\n\t" + ".pushsection __jump_table, \"aw\" \n\t" + _ASM_ALIGN "\n\t" + _ASM_PTR "1b, %l[l_yes], %c0 \n\t" + ".popsection \n\t" + : : "i" (&((char *)key)[branch]) : : l_yes); + return false; l_yes: return true; -- cgit v1.2.3