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);