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-rw-r--r--arch/Kconfig14
-rw-r--r--arch/sparc/include/asm/jump_label.h1
-rw-r--r--arch/x86/Makefile_32.cpu13
-rw-r--r--arch/x86/kernel/alternative.c69
-rw-r--r--arch/x86/kernel/apic/io_apic.c2
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);

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