Commit b9b55c89 authored by Masami Hiramatsu (Google)'s avatar Masami Hiramatsu (Google) Committed by Steven Rostedt (Google)
Browse files

tracing: Add ftrace_partial_regs() for converting ftrace_regs to pt_regs 



Add ftrace_partial_regs() which converts the ftrace_regs to pt_regs.
This is for the eBPF which needs this to keep the same pt_regs interface
to access registers.
Thus when replacing the pt_regs with ftrace_regs in fprobes (which is
used by kprobe_multi eBPF event), this will be used.

If the architecture defines its own ftrace_regs, this copies partial
registers to pt_regs and returns it. If not, ftrace_regs is the same as
pt_regs and ftrace_partial_regs() will return ftrace_regs::regs.

Signed-off-by: default avatarMasami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: default avatarFlorent Revest <revest@chromium.org>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: bpf <bpf@vger.kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Alan Maguire <alan.maguire@oracle.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Link: https://lore.kernel.org/173518996761.391279.4987911298206448122.stgit@devnote2


Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent 762abbc0

arch/arm64/include/asm/ftrace.h

+13 −0
Original line number Diff line number Diff line
@@ -135,6 +135,19 @@ ftrace_regs_get_frame_pointer(const struct ftrace_regs *fregs) 
	return arch_ftrace_regs(fregs)->fp;

}



static __always_inline struct pt_regs *

ftrace_partial_regs(const struct ftrace_regs *fregs, struct pt_regs *regs)

{

	struct __arch_ftrace_regs *afregs = arch_ftrace_regs(fregs);



	memcpy(regs->regs, afregs->regs, sizeof(afregs->regs));

	regs->sp = afregs->sp;

	regs->pc = afregs->pc;

	regs->regs[29] = afregs->fp;

	regs->regs[30] = afregs->lr;

	return regs;

}



int ftrace_regs_query_register_offset(const char *name);



int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec);

arch/riscv/include/asm/ftrace.h

+14 −0
Original line number Diff line number Diff line
@@ -197,6 +197,20 @@ static __always_inline void ftrace_override_function_with_return(struct ftrace_r 
	arch_ftrace_regs(fregs)->epc = arch_ftrace_regs(fregs)->ra;

}



static __always_inline struct pt_regs *

ftrace_partial_regs(const struct ftrace_regs *fregs, struct pt_regs *regs)

{

	struct __arch_ftrace_regs *afregs = arch_ftrace_regs(fregs);



	memcpy(&regs->a0, afregs->args, sizeof(afregs->args));

	regs->epc = afregs->epc;

	regs->ra = afregs->ra;

	regs->sp = afregs->sp;

	regs->s0 = afregs->s0;

	regs->t1 = afregs->t1;

	return regs;

}



int ftrace_regs_query_register_offset(const char *name);



void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,

include/linux/ftrace.h

+17 −0
Original line number Diff line number Diff line
@@ -190,6 +190,23 @@ static __always_inline struct pt_regs *ftrace_get_regs(struct ftrace_regs *fregs 
	return arch_ftrace_get_regs(fregs);

}



#if !defined(CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS) || \

	defined(CONFIG_HAVE_FTRACE_REGS_HAVING_PT_REGS)



static __always_inline struct pt_regs *

ftrace_partial_regs(struct ftrace_regs *fregs, struct pt_regs *regs)

{

	/*

	 * If CONFIG_HAVE_FTRACE_REGS_HAVING_PT_REGS=y, ftrace_regs memory

	 * layout is including pt_regs. So always returns that address.

	 * Since arch_ftrace_get_regs() will check some members and may return

	 * NULL, we can not use it.

	 */

	return &arch_ftrace_regs(fregs)->regs;

}



#endif /* !CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS || CONFIG_HAVE_FTRACE_REGS_HAVING_PT_REGS */



/*

 * 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.