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ftrace: Make DIRECT_CALLS work WITH_ARGS and !WITH_REGS

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Direct called trampolines can be called in two ways:
- either from the ftrace callsite. In this case, they do not access any
  struct ftrace_regs nor pt_regs
- Or, if a ftrace ops is also attached, from the end of a ftrace
  trampoline. In this case, the call_direct_funcs ops is in charge of
  setting the direct call trampoline's address in a struct ftrace_regs

Since:

commit 9705bc7096 ("ftrace: pass fregs to arch_ftrace_set_direct_caller()")

The later case no longer requires a full pt_regs. It only needs a struct
ftrace_regs so DIRECT_CALLS can work with both WITH_ARGS or WITH_REGS.
With architectures like arm64 already abandoning WITH_REGS in favor of
WITH_ARGS, it's important to have DIRECT_CALLS work WITH_ARGS only.

Link: https://lkml.kernel.org/r/20230321140424.345218-7-revest@chromium.org

Signed-off-by: Florent Revest <revest@chromium.org>
Co-developed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Florent Revest 2023-03-21 15:04:23 +01:00 committed by Steven Rostedt (Google)
parent dbaccb618f
commit 60c8971899
3 changed files with 8 additions and 2 deletions
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6
include/linux/ftrace.h
View File

@ -241,6 +241,12 @@ enum {
FTRACE_OPS_FL_DIRECT = BIT(17),
};
#ifndef CONFIG_DYNAMIC_FTRACE_WITH_ARGS
#define FTRACE_OPS_FL_SAVE_ARGS FTRACE_OPS_FL_SAVE_REGS
#else
#define FTRACE_OPS_FL_SAVE_ARGS 0
#endif
/*
* FTRACE_OPS_CMD_* commands allow the ftrace core logic to request changes
* to a ftrace_ops. Note, the requests may fail.

2
kernel/trace/Kconfig
View File

@ -257,7 +257,7 @@ config DYNAMIC_FTRACE_WITH_REGS
config DYNAMIC_FTRACE_WITH_DIRECT_CALLS
def_bool y
depends on DYNAMIC_FTRACE_WITH_REGS
depends on DYNAMIC_FTRACE_WITH_REGS || DYNAMIC_FTRACE_WITH_ARGS
depends on HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
config DYNAMIC_FTRACE_WITH_CALL_OPS

2
kernel/trace/ftrace.c
View File

@ -5288,7 +5288,7 @@ static LIST_HEAD(ftrace_direct_funcs);
static int register_ftrace_function_nolock(struct ftrace_ops *ops);
#define MULTI_FLAGS (FTRACE_OPS_FL_DIRECT | FTRACE_OPS_FL_SAVE_REGS)
#define MULTI_FLAGS (FTRACE_OPS_FL_DIRECT | FTRACE_OPS_FL_SAVE_ARGS)
static int check_direct_multi(struct ftrace_ops *ops)
{