diff options
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/Kconfig | 14 | ||||
| -rw-r--r-- | arch/sparc/include/asm/jump_label.h | 1 | ||||
| -rw-r--r-- | arch/x86/Makefile_32.cpu | 13 | ||||
| -rw-r--r-- | arch/x86/kernel/alternative.c | 69 | ||||
| -rw-r--r-- | arch/x86/kernel/apic/io_apic.c | 2 |
5 files changed, 43 insertions, 56 deletions
diff --git a/arch/Kconfig b/arch/Kconfig index 53d7f619a1b9..8bf0fa652eb6 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -42,6 +42,20 @@ config KPROBES for kernel debugging, non-intrusive instrumentation and testing. If in doubt, say "N". +config JUMP_LABEL + bool "Optimize trace point call sites" + depends on HAVE_ARCH_JUMP_LABEL + help + If it is detected that the compiler has support for "asm goto", + the kernel will compile trace point locations with just a + nop instruction. When trace points are enabled, the nop will + be converted to a jump to the trace function. This technique + lowers overhead and stress on the branch prediction of the + processor. + + On i386, options added to the compiler flags may increase + the size of the kernel slightly. + config OPTPROBES def_bool y depends on KPROBES && HAVE_OPTPROBES diff --git a/arch/sparc/include/asm/jump_label.h b/arch/sparc/include/asm/jump_label.h index 65c0d3029796..427d4684e0d2 100644 --- a/arch/sparc/include/asm/jump_label.h +++ b/arch/sparc/include/asm/jump_label.h @@ -13,6 +13,7 @@ "nop\n\t" \ "nop\n\t" \ ".pushsection __jump_table, \"a\"\n\t"\ + ".align 4\n\t" \ ".word 1b, %l[" #label "], %c0\n\t" \ ".popsection \n\t" \ : : "i" (key) : : label);\ diff --git a/arch/x86/Makefile_32.cpu b/arch/x86/Makefile_32.cpu index 1255d953c65d..f2ee1abb1df9 100644 --- a/arch/x86/Makefile_32.cpu +++ b/arch/x86/Makefile_32.cpu @@ -51,7 +51,18 @@ cflags-$(CONFIG_X86_GENERIC) += $(call tune,generic,$(call tune,i686)) # prologue (push %ebp, mov %esp, %ebp) which breaks the function graph # tracer assumptions. For i686, generic, core2 this is set by the # compiler anyway -cflags-$(CONFIG_FUNCTION_GRAPH_TRACER) += $(call cc-option,-maccumulate-outgoing-args) +ifeq ($(CONFIG_FUNCTION_GRAPH_TRACER), y) +ADD_ACCUMULATE_OUTGOING_ARGS := y +endif + +# Work around to a bug with asm goto with first implementations of it +# in gcc causing gcc to mess up the push and pop of the stack in some +# uses of asm goto. +ifeq ($(CONFIG_JUMP_LABEL), y) +ADD_ACCUMULATE_OUTGOING_ARGS := y +endif + +cflags-$(ADD_ACCUMULATE_OUTGOING_ARGS) += $(call cc-option,-maccumulate-outgoing-args) # Bug fix for binutils: this option is required in order to keep # binutils from generating NOPL instructions against our will. diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index 5ceeca382820..5079f24c955a 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -644,65 +644,26 @@ void *__kprobes text_poke_smp(void *addr, const void *opcode, size_t len) #if defined(CONFIG_DYNAMIC_FTRACE) || defined(HAVE_JUMP_LABEL) -unsigned char ideal_nop5[IDEAL_NOP_SIZE_5]; +#ifdef CONFIG_X86_64 +unsigned char ideal_nop5[5] = { 0x66, 0x66, 0x66, 0x66, 0x90 }; +#else +unsigned char ideal_nop5[5] = { 0x3e, 0x8d, 0x74, 0x26, 0x00 }; +#endif void __init arch_init_ideal_nop5(void) { - extern const unsigned char ftrace_test_p6nop[]; - extern const unsigned char ftrace_test_nop5[]; - extern const unsigned char ftrace_test_jmp[]; - int faulted = 0; - /* - * There is no good nop for all x86 archs. - * We will default to using the P6_NOP5, but first we - * will test to make sure that the nop will actually - * work on this CPU. If it faults, we will then - * go to a lesser efficient 5 byte nop. If that fails - * we then just use a jmp as our nop. This isn't the most - * efficient nop, but we can not use a multi part nop - * since we would then risk being preempted in the middle - * of that nop, and if we enabled tracing then, it might - * cause a system crash. + * There is no good nop for all x86 archs. This selection + * algorithm should be unified with the one in find_nop_table(), + * but this should be good enough for now. * - * TODO: check the cpuid to determine the best nop. + * For cases other than the ones below, use the safe (as in + * always functional) defaults above. */ - asm volatile ( - "ftrace_test_jmp:" - "jmp ftrace_test_p6nop\n" - "nop\n" - "nop\n" - "nop\n" /* 2 byte jmp + 3 bytes */ - "ftrace_test_p6nop:" - P6_NOP5 - "jmp 1f\n" - "ftrace_test_nop5:" - ".byte 0x66,0x66,0x66,0x66,0x90\n" - "1:" - ".section .fixup, \"ax\"\n" - "2: movl $1, %0\n" - " jmp ftrace_test_nop5\n" - "3: movl $2, %0\n" - " jmp 1b\n" - ".previous\n" - _ASM_EXTABLE(ftrace_test_p6nop, 2b) - _ASM_EXTABLE(ftrace_test_nop5, 3b) - : "=r"(faulted) : "0" (faulted)); - - switch (faulted) { - case 0: - pr_info("converting mcount calls to 0f 1f 44 00 00\n"); - memcpy(ideal_nop5, ftrace_test_p6nop, IDEAL_NOP_SIZE_5); - break; - case 1: - pr_info("converting mcount calls to 66 66 66 66 90\n"); - memcpy(ideal_nop5, ftrace_test_nop5, IDEAL_NOP_SIZE_5); - break; - case 2: - pr_info("converting mcount calls to jmp . + 5\n"); - memcpy(ideal_nop5, ftrace_test_jmp, IDEAL_NOP_SIZE_5); - break; - } - +#ifdef CONFIG_X86_64 + /* Don't use these on 32 bits due to broken virtualizers */ + if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) + memcpy(ideal_nop5, p6_nops[5], 5); +#endif } #endif diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c index 0929191d83cf..7cc0a721f628 100644 --- a/arch/x86/kernel/apic/io_apic.c +++ b/arch/x86/kernel/apic/io_apic.c @@ -3109,7 +3109,7 @@ void destroy_irq(unsigned int irq) irq_set_status_flags(irq, IRQ_NOREQUEST|IRQ_NOPROBE); - if (intr_remapping_enabled) + if (irq_remapped(cfg)) free_irte(irq); raw_spin_lock_irqsave(&vector_lock, flags); __clear_irq_vector(irq, cfg); |