Commit 94d095ff authored by Mark Rutland's avatar Mark Rutland Committed by Will Deacon
Browse files

ftrace: abstract DYNAMIC_FTRACE_WITH_ARGS accesses 



In subsequent patches we'll arrange for architectures to have an
ftrace_regs which is entirely distinct from pt_regs. In preparation for
this, we need to minimize the use of pt_regs to where strictly necessary
in the core ftrace code.

This patch adds new ftrace_regs_{get,set}_*() helpers which can be used
to manipulate ftrace_regs. When CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS=y,
these can always be used on any ftrace_regs, and when
CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS=n these can be used when regs are
available. A new ftrace_regs_has_args(fregs) helper is added which code
can use to check when these are usable.

Co-developed-by: default avatarFlorent Revest <revest@chromium.org>
Signed-off-by: default avatarFlorent Revest <revest@chromium.org>
Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Reviewed-by: default avatarMasami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
Link: https://lore.kernel.org/r/20221103170520.931305-4-mark.rutland@arm.com


Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent 0ef86097

arch/powerpc/include/asm/ftrace.h

+19 −0
Original line number Diff line number Diff line
@@ -44,6 +44,25 @@ ftrace_regs_set_instruction_pointer(struct ftrace_regs *fregs, 
	regs_set_return_ip(&fregs->regs, ip);

}



static __always_inline unsigned long

ftrace_regs_get_instruction_pointer(struct ftrace_regs *fregs)

{

	return instruction_pointer(&fregs->regs);

}



#define ftrace_regs_get_argument(fregs, n) \

	regs_get_kernel_argument(&(fregs)->regs, n)

#define ftrace_regs_get_stack_pointer(fregs) \

	kernel_stack_pointer(&(fregs)->regs)

#define ftrace_regs_return_value(fregs) \

	regs_return_value(&(fregs)->regs)

#define ftrace_regs_set_return_value(fregs, ret) \

	regs_set_return_value(&(fregs)->regs, ret)

#define ftrace_override_function_with_return(fregs) \

	override_function_with_return(&(fregs)->regs)

#define ftrace_regs_query_register_offset(name) \

	regs_query_register_offset(name)



struct ftrace_ops;



#define ftrace_graph_func ftrace_graph_func

arch/s390/include/asm/ftrace.h

+19 −0
Original line number Diff line number Diff line
@@ -54,6 +54,12 @@ static __always_inline struct pt_regs *arch_ftrace_get_regs(struct ftrace_regs * 
	return NULL;

}



static __always_inline unsigned long

ftrace_regs_get_instruction_pointer(const struct ftrace_regs *fregs)

{

	return fregs->regs.psw.addr;

}



static __always_inline void

ftrace_regs_set_instruction_pointer(struct ftrace_regs *fregs,

				    unsigned long ip)
@@ -61,6 +67,19 @@ ftrace_regs_set_instruction_pointer(struct ftrace_regs *fregs, 
	fregs->regs.psw.addr = ip;

}



#define ftrace_regs_get_argument(fregs, n) \

	regs_get_kernel_argument(&(fregs)->regs, n)

#define ftrace_regs_get_stack_pointer(fregs) \

	kernel_stack_pointer(&(fregs)->regs)

#define ftrace_regs_return_value(fregs) \

	regs_return_value(&(fregs)->regs)

#define ftrace_regs_set_return_value(fregs, ret) \

	regs_set_return_value(&(fregs)->regs, ret)

#define ftrace_override_function_with_return(fregs) \

	override_function_with_return(&(fregs)->regs)

#define ftrace_regs_query_register_offset(name) \

	regs_query_register_offset(name)



#ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS

/*

 * When an ftrace registered caller is tracing a function that is

arch/x86/include/asm/ftrace.h

+16 −0
Original line number Diff line number Diff line
@@ -51,6 +51,22 @@ arch_ftrace_get_regs(struct ftrace_regs *fregs) 
#define ftrace_regs_set_instruction_pointer(fregs, _ip)	\

	do { (fregs)->regs.ip = (_ip); } while (0)



#define ftrace_regs_get_instruction_pointer(fregs) \

	((fregs)->regs.ip)



#define ftrace_regs_get_argument(fregs, n) \

	regs_get_kernel_argument(&(fregs)->regs, n)

#define ftrace_regs_get_stack_pointer(fregs) \

	kernel_stack_pointer(&(fregs)->regs)

#define ftrace_regs_return_value(fregs) \

	regs_return_value(&(fregs)->regs)

#define ftrace_regs_set_return_value(fregs, ret) \

	regs_set_return_value(&(fregs)->regs, ret)

#define ftrace_override_function_with_return(fregs) \

	override_function_with_return(&(fregs)->regs)

#define ftrace_regs_query_register_offset(name) \

	regs_query_register_offset(name)



struct ftrace_ops;

#define ftrace_graph_func ftrace_graph_func

void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,

include/linux/ftrace.h

+29 −0
Original line number Diff line number Diff line
@@ -126,6 +126,35 @@ static __always_inline struct pt_regs *ftrace_get_regs(struct ftrace_regs *fregs 
	return arch_ftrace_get_regs(fregs);

}



/*

 * When true, the ftrace_regs_{get,set}_*() functions may be used on fregs.

 * Note: this can be true even when ftrace_get_regs() cannot provide a pt_regs.

 */

static __always_inline bool ftrace_regs_has_args(struct ftrace_regs *fregs)

{

	if (IS_ENABLED(CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS))

		return true;



	return ftrace_get_regs(fregs) != NULL;

}



#ifndef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS

#define ftrace_regs_get_instruction_pointer(fregs) \

	instruction_pointer(ftrace_get_regs(fregs))

#define ftrace_regs_get_argument(fregs, n) \

	regs_get_kernel_argument(ftrace_get_regs(fregs), n)

#define ftrace_regs_get_stack_pointer(fregs) \

	kernel_stack_pointer(ftrace_get_regs(fregs))

#define ftrace_regs_return_value(fregs) \

	regs_return_value(ftrace_get_regs(fregs))

#define ftrace_regs_set_return_value(fregs, ret) \

	regs_set_return_value(ftrace_get_regs(fregs), ret)

#define ftrace_override_function_with_return(fregs) \

	override_function_with_return(ftrace_get_regs(fregs))

#define ftrace_regs_query_register_offset(name) \

	regs_query_register_offset(name)

#endif



typedef void (*ftrace_func_t)(unsigned long ip, unsigned long parent_ip,

			      struct ftrace_ops *op, struct ftrace_regs *fregs);

kernel/trace/Kconfig

+3 −3
Original line number Diff line number Diff line
@@ -46,10 +46,10 @@ config HAVE_DYNAMIC_FTRACE_WITH_ARGS 
	bool

	help

	 If this is set, then arguments and stack can be found from

	 the pt_regs passed into the function callback regs parameter

	 the ftrace_regs passed into the function callback regs parameter

	 by default, even without setting the REGS flag in the ftrace_ops.

	 This allows for use of regs_get_kernel_argument() and

	 kernel_stack_pointer().

	 This allows for use of ftrace_regs_get_argument() and

	 ftrace_regs_get_stack_pointer().



config HAVE_DYNAMIC_FTRACE_NO_PATCHABLE

	bool