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authorSteven Rostedt <srostedt@redhat.com>2012-04-30 16:20:23 -0400
committerSteven Rostedt <rostedt@goodmis.org>2012-07-19 13:20:03 -0400
commit08f6fba503111e0336f2b4d6915a4a18f9b60e51 (patch)
tree119f971348614154552b70fb5cbe358f7c532a18 /arch/x86/kernel/ftrace.c
parent28fb5dfa783c25dbeeb25a72663f8066a3a517f5 (diff)
ftrace/x86: Add separate function to save regs
Add a way to have different functions calling different trampolines. If a ftrace_ops wants regs saved on the return, then have only the functions with ops registered to save regs. Functions registered by other ops would not be affected, unless the functions overlap. If one ftrace_ops registered functions A, B and C and another ops registered fucntions to save regs on A, and D, then only functions A and D would be saving regs. Function B and C would work as normal. Although A is registered by both ops: normal and saves regs; this is fine as saving the regs is needed to satisfy one of the ops that calls it but the regs are ignored by the other ops function. x86_64 implements the full regs saving, and i386 just passes a NULL for regs to satisfy the ftrace_ops passing. Where an arch must supply both regs and ftrace_ops parameters, even if regs is just NULL. It is OK for an arch to pass NULL regs. All function trace users that require regs passing must add the flag FTRACE_OPS_FL_SAVE_REGS when registering the ftrace_ops. If the arch does not support saving regs then the ftrace_ops will fail to register. The flag FTRACE_OPS_FL_SAVE_REGS_IF_SUPPORTED may be set that will prevent the ftrace_ops from failing to register. In this case, the handler may either check if regs is not NULL or check if ARCH_SUPPORTS_FTRACE_SAVE_REGS. If the arch supports passing regs it will set this macro and pass regs for ops that request them. All other archs will just pass NULL. Link: Link: http://lkml.kernel.org/r/20120711195745.107705970@goodmis.org Cc: Alexander van Heukelum <heukelum@fastmail.fm> Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'arch/x86/kernel/ftrace.c')
-rw-r--r--arch/x86/kernel/ftrace.c77
1 files changed, 73 insertions, 4 deletions
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index c3a7cb4bf6e6..b90eb1a13071 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -206,6 +206,23 @@ static int
ftrace_modify_code(unsigned long ip, unsigned const char *old_code,
unsigned const char *new_code);
+#ifdef ARCH_SUPPORTS_FTRACE_SAVE_REGS
+/*
+ * Should never be called:
+ * As it is only called by __ftrace_replace_code() which is called by
+ * ftrace_replace_code() that x86 overrides, and by ftrace_update_code()
+ * which is called to turn mcount into nops or nops into function calls
+ * but not to convert a function from not using regs to one that uses
+ * regs, which ftrace_modify_call() is for.
+ */
+int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
+ unsigned long addr)
+{
+ WARN_ON(1);
+ return -EINVAL;
+}
+#endif
+
int ftrace_update_ftrace_func(ftrace_func_t func)
{
unsigned long ip = (unsigned long)(&ftrace_call);
@@ -220,6 +237,16 @@ int ftrace_update_ftrace_func(ftrace_func_t func)
ret = ftrace_modify_code(ip, old, new);
+#ifdef ARCH_SUPPORTS_FTRACE_SAVE_REGS
+ /* Also update the regs callback function */
+ if (!ret) {
+ ip = (unsigned long)(&ftrace_regs_call);
+ memcpy(old, &ftrace_regs_call, MCOUNT_INSN_SIZE);
+ new = ftrace_call_replace(ip, (unsigned long)func);
+ ret = ftrace_modify_code(ip, old, new);
+ }
+#endif
+
atomic_dec(&modifying_ftrace_code);
return ret;
@@ -299,6 +326,32 @@ static int add_brk_on_nop(struct dyn_ftrace *rec)
return add_break(rec->ip, old);
}
+/*
+ * If the record has the FTRACE_FL_REGS set, that means that it
+ * wants to convert to a callback that saves all regs. If FTRACE_FL_REGS
+ * is not not set, then it wants to convert to the normal callback.
+ */
+static unsigned long get_ftrace_addr(struct dyn_ftrace *rec)
+{
+ if (rec->flags & FTRACE_FL_REGS)
+ return (unsigned long)FTRACE_REGS_ADDR;
+ else
+ return (unsigned long)FTRACE_ADDR;
+}
+
+/*
+ * The FTRACE_FL_REGS_EN is set when the record already points to
+ * a function that saves all the regs. Basically the '_EN' version
+ * represents the current state of the function.
+ */
+static unsigned long get_ftrace_old_addr(struct dyn_ftrace *rec)
+{
+ if (rec->flags & FTRACE_FL_REGS_EN)
+ return (unsigned long)FTRACE_REGS_ADDR;
+ else
+ return (unsigned long)FTRACE_ADDR;
+}
+
static int add_breakpoints(struct dyn_ftrace *rec, int enable)
{
unsigned long ftrace_addr;
@@ -306,7 +359,7 @@ static int add_breakpoints(struct dyn_ftrace *rec, int enable)
ret = ftrace_test_record(rec, enable);
- ftrace_addr = (unsigned long)FTRACE_ADDR;
+ ftrace_addr = get_ftrace_addr(rec);
switch (ret) {
case FTRACE_UPDATE_IGNORE:
@@ -316,6 +369,10 @@ static int add_breakpoints(struct dyn_ftrace *rec, int enable)
/* converting nop to call */
return add_brk_on_nop(rec);
+ case FTRACE_UPDATE_MODIFY_CALL_REGS:
+ case FTRACE_UPDATE_MODIFY_CALL:
+ ftrace_addr = get_ftrace_old_addr(rec);
+ /* fall through */
case FTRACE_UPDATE_MAKE_NOP:
/* converting a call to a nop */
return add_brk_on_call(rec, ftrace_addr);
@@ -360,13 +417,21 @@ static int remove_breakpoint(struct dyn_ftrace *rec)
* If not, don't touch the breakpoint, we make just create
* a disaster.
*/
- ftrace_addr = (unsigned long)FTRACE_ADDR;
+ ftrace_addr = get_ftrace_addr(rec);
+ nop = ftrace_call_replace(ip, ftrace_addr);
+
+ if (memcmp(&ins[1], &nop[1], MCOUNT_INSN_SIZE - 1) == 0)
+ goto update;
+
+ /* Check both ftrace_addr and ftrace_old_addr */
+ ftrace_addr = get_ftrace_old_addr(rec);
nop = ftrace_call_replace(ip, ftrace_addr);
if (memcmp(&ins[1], &nop[1], MCOUNT_INSN_SIZE - 1) != 0)
return -EINVAL;
}
+ update:
return probe_kernel_write((void *)ip, &nop[0], 1);
}
@@ -405,12 +470,14 @@ static int add_update(struct dyn_ftrace *rec, int enable)
ret = ftrace_test_record(rec, enable);
- ftrace_addr = (unsigned long)FTRACE_ADDR;
+ ftrace_addr = get_ftrace_addr(rec);
switch (ret) {
case FTRACE_UPDATE_IGNORE:
return 0;
+ case FTRACE_UPDATE_MODIFY_CALL_REGS:
+ case FTRACE_UPDATE_MODIFY_CALL:
case FTRACE_UPDATE_MAKE_CALL:
/* converting nop to call */
return add_update_call(rec, ftrace_addr);
@@ -455,12 +522,14 @@ static int finish_update(struct dyn_ftrace *rec, int enable)
ret = ftrace_update_record(rec, enable);
- ftrace_addr = (unsigned long)FTRACE_ADDR;
+ ftrace_addr = get_ftrace_addr(rec);
switch (ret) {
case FTRACE_UPDATE_IGNORE:
return 0;
+ case FTRACE_UPDATE_MODIFY_CALL_REGS:
+ case FTRACE_UPDATE_MODIFY_CALL:
case FTRACE_UPDATE_MAKE_CALL:
/* converting nop to call */
return finish_update_call(rec, ftrace_addr);