jump label: Make dynamic no-op selection available outside of ftrace

Move Steve's code for finding the best 5-byte no-op from ftrace.c to
alternative.c. The idea is that other consumers (in this case jump label)
want to make use of that code.

Signed-off-by: Jason Baron <jbaron@redhat.com>
LKML-Reference: <96259ae74172dcac99c0020c249743c523a92e18.1284733808.git.jbaron@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

diff --git a/arch/x86/include/asm/alternative.h b/arch/x86/include/asm/alternative.h
index bc6abb7bc7ee3084aa8b5d87ae19244715469990..27a35b6891805111889c3bf7a339697b7951c954 100644 (file)
--- a/arch/x86/include/asm/alternative.h
+++ b/arch/x86/include/asm/alternative.h
@@ -180,4 +180,12 @@ static inline void apply_paravirt(struct paravirt_patch_site *start,
 extern void *text_poke(void *addr, const void *opcode, size_t len);
 extern void *text_poke_smp(void *addr, const void *opcode, size_t len);
 
+#if defined(CONFIG_DYNAMIC_FTRACE)
+#define IDEAL_NOP_SIZE_5 5
+extern unsigned char ideal_nop5[IDEAL_NOP_SIZE_5];
+extern void arch_init_ideal_nop5(void);
+#else
+static inline void arch_init_ideal_nop5(void) {}
+#endif
+
 #endif /* _ASM_X86_ALTERNATIVE_H */

diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index f65ab8b014c4f42421d77200243c39c7fd252165..1849d8036ee8930eeca4713e64da5e81df870eff 100644 (file)
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -641,3 +641,67 @@ void *__kprobes text_poke_smp(void *addr, const void *opcode, size_t len)
        return addr;
 }
 
+#if defined(CONFIG_DYNAMIC_FTRACE)
+
+unsigned char ideal_nop5[IDEAL_NOP_SIZE_5];
+
+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.
+        *
+        * TODO: check the cpuid to determine the best nop.
+        */
+       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;
+       }
+
+}
+#endif

diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index cd37469b54eeed3fc479d2c931d8d2ed933ea411..3afb33f14d2d2c86a3c961d87aaae531d2631ac8 100644 (file)
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -257,14 +257,9 @@ do_ftrace_mod_code(unsigned long ip, void *new_code)
        return mod_code_status;
 }
 
-
-
-
-static unsigned char ftrace_nop[MCOUNT_INSN_SIZE];
-
 static unsigned char *ftrace_nop_replace(void)
 {
-       return ftrace_nop;
+       return ideal_nop5;
 }
 
 static int
@@ -338,62 +333,6 @@ int ftrace_update_ftrace_func(ftrace_func_t func)
 
 int __init ftrace_dyn_arch_init(void *data)
 {
-       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.
-        *
-        * TODO: check the cpuid to determine the best nop.
-        */
-       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(ftrace_nop, ftrace_test_p6nop, MCOUNT_INSN_SIZE);
-               break;
-       case 1:
-               pr_info("converting mcount calls to 66 66 66 66 90\n");
-               memcpy(ftrace_nop, ftrace_test_nop5, MCOUNT_INSN_SIZE);
-               break;
-       case 2:
-               pr_info("converting mcount calls to jmp . + 5\n");
-               memcpy(ftrace_nop, ftrace_test_jmp, MCOUNT_INSN_SIZE);
-               break;
-       }
-
        /* The return code is retured via data */
        *(unsigned long *)data = 0;
 

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index c3a4fbb2b996d00277d6523cb76b74e2c5944621..00e167870f714ab0799838865eec35bd13ce5601 100644 (file)
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -112,6 +112,7 @@
 #include <asm/numa_64.h>
 #endif
 #include <asm/mce.h>
+#include <asm/alternative.h>
 
 /*
  * end_pfn only includes RAM, while max_pfn_mapped includes all e820 entries.
@@ -726,6 +727,7 @@ void __init setup_arch(char **cmdline_p)
 {
        int acpi = 0;
        int k8 = 0;
+       unsigned long flags;
 
 #ifdef CONFIG_X86_32
        memcpy(&boot_cpu_data, &new_cpu_data, sizeof(new_cpu_data));
@@ -1071,6 +1073,10 @@ void __init setup_arch(char **cmdline_p)
        x86_init.oem.banner();
 
        mcheck_init();
+
+       local_irq_save(flags);
+       arch_init_ideal_nop5();
+       local_irq_restore(flags);
 }
 
 #ifdef CONFIG_X86_32