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authorSteven Rostedt (Red Hat) <rostedt@goodmis.org>2015-11-25 14:13:11 -0500
committerSteven Rostedt <rostedt@goodmis.org>2015-11-25 15:24:16 -0500
commitb05086c77a162dd8ef79606cb4723f1fc1448bb1 (patch)
treee3939af4c5377ceb2efe4fc791cdc797ee2c13b9 /arch/x86/kernel/ftrace.c
parent02a392a0439ffdc62b4d8f17bd18d68736b166a9 (diff)
downloadlinux-b05086c77a162dd8ef79606cb4723f1fc1448bb1.tar.bz2
ftrace: Add variable ftrace_expected for archs to show expected code
When an anomaly is found while modifying function code, ftrace_bug() is called which disables the function tracing infrastructure and reports information about what failed. If the code that is to be replaced does not match what is expected, then actual code is shown. Currently there is no arch generic way to show what was expected. Add a new variable pointer calld ftrace_expected that the arch code can set to point to what it expected so that ftrace_bug() can report the actual text as well as the text that was expected to be there. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'arch/x86/kernel/ftrace.c')
-rw-r--r--arch/x86/kernel/ftrace.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 311bcf338f07..909da012406d 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -105,6 +105,8 @@ ftrace_modify_code_direct(unsigned long ip, unsigned const char *old_code,
{
unsigned char replaced[MCOUNT_INSN_SIZE];
+ ftrace_expected = old_code;
+
/*
* Note: Due to modules and __init, code can
* disappear and change, we need to protect against faulting
@@ -154,6 +156,8 @@ int ftrace_make_nop(struct module *mod,
if (addr == MCOUNT_ADDR)
return ftrace_modify_code_direct(rec->ip, old, new);
+ ftrace_expected = NULL;
+
/* Normal cases use add_brk_on_nop */
WARN_ONCE(1, "invalid use of ftrace_make_nop");
return -EINVAL;
@@ -220,6 +224,7 @@ int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
unsigned long addr)
{
WARN_ON(1);
+ ftrace_expected = NULL;
return -EINVAL;
}
@@ -314,6 +319,8 @@ static int add_break(unsigned long ip, const char *old)
if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))
return -EFAULT;
+ ftrace_expected = old;
+
/* Make sure it is what we expect it to be */
if (memcmp(replaced, old, MCOUNT_INSN_SIZE) != 0)
return -EINVAL;
@@ -413,6 +420,8 @@ static int remove_breakpoint(struct dyn_ftrace *rec)
ftrace_addr = ftrace_get_addr_curr(rec);
nop = ftrace_call_replace(ip, ftrace_addr);
+ ftrace_expected = nop;
+
if (memcmp(&ins[1], &nop[1], MCOUNT_INSN_SIZE - 1) != 0)
return -EINVAL;
}