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Date: Wed, 13 Oct 2010 17:46:15 -0400
From: Jason Baron <jbaron@...hat.com>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org,
Andrew Morton <akpm@...ux-foundation.org>,
Frederic Weisbecker <fweisbec@...il.com>
Subject: Re: [PATCH 0/9] [GIT PULL] tracing: updates for 2.6.37
On Fri, Oct 08, 2010 at 11:59:47PM -0400, Steven Rostedt wrote:
> On Fri, 2010-10-08 at 10:45 +0200, Ingo Molnar wrote:
> > hm, i'm getting:
> >
> > arch/x86/kernel/alternative.c: Assembler messages:
> > arch/x86/kernel/alternative.c:674: Error: symbol `ftrace_test_jmp' is already defined
> > arch/x86/kernel/alternative.c:678: Error: symbol `ftrace_test_p6nop' is already defined
> > arch/x86/kernel/alternative.c:680: Error: symbol `ftrace_test_nop5' is already defined
> >
> > Config attached.
>
> I'll see if I can get to this early next week. I'll be leaving to NYC on
> Monday for the End Users Summit. I'll try to look at this while there.
>
> Thanks!
>
> -- Steve
>
just saw this...looks like this is broken for gcc < 4.5. Anyways, the
patch below fixes the compilation by making arch_init_ideal_nop5()
static (and moving its definition ahead of its usage). I'm not quite
sure why this makes the compiler happy...applies on top of this series.
thanks,
-Jason
make arch_init_ideal_nop5() static. fixes compilation error:
arch/x86/kernel/alternative.c: Assembler messages:
arch/x86/kernel/alternative.c:674: Error: symbol `ftrace_test_jmp' is already defined
arch/x86/kernel/alternative.c:678: Error: symbol `ftrace_test_p6nop' is already defined
arch/x86/kernel/alternative.c:680: Error: symbol `ftrace_test_nop5' is already defined
Signed-off-by: Jason Baron <jbaron@...hat.com>
---
arch/x86/include/asm/alternative.h | 1 -
arch/x86/kernel/alternative.c | 130 ++++++++++++++++++------------------
2 files changed, 65 insertions(+), 66 deletions(-)
diff --git a/arch/x86/include/asm/alternative.h b/arch/x86/include/asm/alternative.h
index 76561d2..2a7f618 100644
--- a/arch/x86/include/asm/alternative.h
+++ b/arch/x86/include/asm/alternative.h
@@ -186,7 +186,6 @@ extern void *text_poke_smp(void *addr, const void *opcode, size_t len);
#if defined(CONFIG_DYNAMIC_FTRACE) || defined(HAVE_JUMP_LABEL)
#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
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index d8b5b21..2331b68 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -452,6 +452,71 @@ extern struct paravirt_patch_site __start_parainstructions[],
__stop_parainstructions[];
#endif /* CONFIG_PARAVIRT */
+#if defined(CONFIG_DYNAMIC_FTRACE) || defined(HAVE_JUMP_LABEL)
+
+unsigned char ideal_nop5[IDEAL_NOP_SIZE_5];
+
+static 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
+
void __init alternative_instructions(void)
{
unsigned long flags;
@@ -645,68 +710,3 @@ void *__kprobes text_poke_smp(void *addr, const void *opcode, size_t len)
stop_machine(stop_machine_text_poke, (void *)&tpp, NULL);
return addr;
}
-
-#if defined(CONFIG_DYNAMIC_FTRACE) || defined(HAVE_JUMP_LABEL)
-
-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
--
1.7.0.1
--
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