summaryrefslogtreecommitdiff
path: root/arch/x86/kernel/entry_32.S
diff options
context:
space:
mode:
authorFrederic Weisbecker <fweisbec@gmail.com>2008-11-16 06:02:06 +0100
committerIngo Molnar <mingo@elte.hu>2008-11-16 07:57:38 +0100
commite7d3737ea1b102030f44e96c97754101e41515f0 (patch)
tree44fdc3dea100d1fa639e6ba3cb1bfca2ab40e70b /arch/x86/kernel/entry_32.S
parentb01c746617da5e260803eb10ed64ca043e9a1241 (diff)
tracing/function-return-tracer: support for dynamic ftrace on function return tracer
This patch adds the support for dynamic tracing on the function return tracer. The whole difference with normal dynamic function tracing is that we don't need to hook on a particular callback. The only pro that we want is to nop or set dynamically the calls to ftrace_caller (which is ftrace_return_caller here). Some security checks ensure that we are not trying to launch dynamic tracing for return tracing while normal function tracing is already running. An example of trace with getnstimeofday set as a filter: ktime_get_ts+0x22/0x50 -> getnstimeofday (2283 ns) ktime_get_ts+0x22/0x50 -> getnstimeofday (1396 ns) ktime_get_ts+0x22/0x50 -> getnstimeofday (1382 ns) ktime_get_ts+0x22/0x50 -> getnstimeofday (1825 ns) ktime_get_ts+0x22/0x50 -> getnstimeofday (1426 ns) ktime_get_ts+0x22/0x50 -> getnstimeofday (1464 ns) ktime_get_ts+0x22/0x50 -> getnstimeofday (1524 ns) ktime_get_ts+0x22/0x50 -> getnstimeofday (1382 ns) ktime_get_ts+0x22/0x50 -> getnstimeofday (1382 ns) ktime_get_ts+0x22/0x50 -> getnstimeofday (1434 ns) ktime_get_ts+0x22/0x50 -> getnstimeofday (1464 ns) ktime_get_ts+0x22/0x50 -> getnstimeofday (1502 ns) ktime_get_ts+0x22/0x50 -> getnstimeofday (1404 ns) ktime_get_ts+0x22/0x50 -> getnstimeofday (1397 ns) ktime_get_ts+0x22/0x50 -> getnstimeofday (1051 ns) ktime_get_ts+0x22/0x50 -> getnstimeofday (1314 ns) ktime_get_ts+0x22/0x50 -> getnstimeofday (1344 ns) ktime_get_ts+0x22/0x50 -> getnstimeofday (1163 ns) ktime_get_ts+0x22/0x50 -> getnstimeofday (1390 ns) ktime_get_ts+0x22/0x50 -> getnstimeofday (1374 ns) Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/kernel/entry_32.S')
-rw-r--r--arch/x86/kernel/entry_32.S18
1 files changed, 11 insertions, 7 deletions
diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index f97621149839..74defe21ba42 100644
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -1190,7 +1190,7 @@ ENTRY(mcount)
jnz trace
#ifdef CONFIG_FUNCTION_RET_TRACER
cmpl $ftrace_stub, ftrace_function_return
- jnz trace_return
+ jnz ftrace_return_caller
#endif
.globl ftrace_stub
ftrace_stub:
@@ -1211,9 +1211,15 @@ trace:
popl %ecx
popl %eax
jmp ftrace_stub
+END(mcount)
+#endif /* CONFIG_DYNAMIC_FTRACE */
+#endif /* CONFIG_FUNCTION_TRACER */
#ifdef CONFIG_FUNCTION_RET_TRACER
-trace_return:
+ENTRY(ftrace_return_caller)
+ cmpl $0, function_trace_stop
+ jne ftrace_stub
+
pushl %eax
pushl %ecx
pushl %edx
@@ -1223,7 +1229,8 @@ trace_return:
popl %edx
popl %ecx
popl %eax
- jmp ftrace_stub
+ ret
+END(ftrace_return_caller)
.globl return_to_handler
return_to_handler:
@@ -1237,10 +1244,7 @@ return_to_handler:
popl %ecx
popl %eax
ret
-#endif /* CONFIG_FUNCTION_RET_TRACER */
-END(mcount)
-#endif /* CONFIG_DYNAMIC_FTRACE */
-#endif /* CONFIG_FUNCTION_TRACER */
+#endif
.section .rodata,"a"
#include "syscall_table_32.S"