Commit 7495e179 authored by Sven Schnelle's avatar Sven Schnelle Committed by Steven Rostedt (Google)
Browse files

s390/tracing: Enable HAVE_FTRACE_GRAPH_FUNC 

Add ftrace_graph_func() which is required for fprobe to access registers.
This also eliminates the need for calling prepare_ftrace_return() from
ftrace_caller().

Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Florent Revest <revest@chromium.org>
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>
Link: https://lore.kernel.org/173519002875.391279.7060964632119674159.stgit@devnote2


Signed-off-by: default avatarSven Schnelle <svens@linux.ibm.com>
Acked-by: default avatarHeiko Carstens <hca@linux.ibm.com>
Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent a762e926

arch/s390/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -190,6 +190,7 @@ config S390 
	select HAVE_EFFICIENT_UNALIGNED_ACCESS

	select HAVE_GUP_FAST

	select HAVE_FENTRY

	select HAVE_FTRACE_GRAPH_FUNC

	select HAVE_FTRACE_MCOUNT_RECORD

	select HAVE_FUNCTION_ARG_ACCESS_API

	select HAVE_FUNCTION_ERROR_INJECTION

arch/s390/include/asm/ftrace.h

+5 −0
Original line number Diff line number Diff line
@@ -39,6 +39,7 @@ struct dyn_arch_ftrace { }; 


struct module;

struct dyn_ftrace;

struct ftrace_ops;



bool ftrace_need_init_nop(void);

#define ftrace_need_init_nop ftrace_need_init_nop
@@ -122,6 +123,10 @@ static inline bool arch_syscall_match_sym_name(const char *sym, 
	return !strcmp(sym + 7, name) || !strcmp(sym + 8, name);

}



void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,

		       struct ftrace_ops *op, struct ftrace_regs *fregs);

#define ftrace_graph_func ftrace_graph_func



#endif /* __ASSEMBLY__ */



#ifdef CONFIG_FUNCTION_TRACER

arch/s390/kernel/entry.h

+0 −1
Original line number Diff line number Diff line
@@ -41,7 +41,6 @@ void do_restart(void *arg); 
void __init startup_init(void);

void die(struct pt_regs *regs, const char *str);

int setup_profiling_timer(unsigned int multiplier);

unsigned long prepare_ftrace_return(unsigned long parent, unsigned long sp, unsigned long ip);



struct s390_mmap_arg_struct;

struct fadvise64_64_args;

arch/s390/kernel/ftrace.c

+14 −34
Original line number Diff line number Diff line
@@ -261,43 +261,23 @@ void ftrace_arch_code_modify_post_process(void) 
}



#ifdef CONFIG_FUNCTION_GRAPH_TRACER

/*

 * Hook the return address and push it in the stack of return addresses

 * in current thread info.

 */

unsigned long prepare_ftrace_return(unsigned long ra, unsigned long sp,

				    unsigned long ip)

{

	if (unlikely(ftrace_graph_is_dead()))

		goto out;

	if (unlikely(atomic_read(&current->tracing_graph_pause)))

		goto out;

	ip -= MCOUNT_INSN_SIZE;

	if (!function_graph_enter(ra, ip, 0, (void *) sp))

		ra = (unsigned long) return_to_handler;

out:

	return ra;

}

NOKPROBE_SYMBOL(prepare_ftrace_return);



/*

 * Patch the kernel code at ftrace_graph_caller location. The instruction

 * there is branch relative on condition. To enable the ftrace graph code

 * block, we simply patch the mask field of the instruction to zero and

 * turn the instruction into a nop.

 * To disable the ftrace graph code the mask field will be patched to

 * all ones, which turns the instruction into an unconditional branch.

 */

int ftrace_enable_ftrace_graph_caller(void)

void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,

		       struct ftrace_ops *op, struct ftrace_regs *fregs)

{

	/* Expect brc 0xf,... */

	return ftrace_patch_branch_mask(ftrace_graph_caller, 0xa7f4, false);

}

	unsigned long *parent = &arch_ftrace_regs(fregs)->regs.gprs[14];

	int bit;



int ftrace_disable_ftrace_graph_caller(void)

{

	/* Expect brc 0x0,... */

	return ftrace_patch_branch_mask(ftrace_graph_caller, 0xa704, true);

	if (unlikely(ftrace_graph_is_dead()))

		return;

	if (unlikely(atomic_read(&current->tracing_graph_pause)))

		return;

	bit = ftrace_test_recursion_trylock(ip, *parent);

	if (bit < 0)

		return;

	if (!function_graph_enter_regs(*parent, ip, 0, parent, fregs))

		*parent = (unsigned long)&return_to_handler;

	ftrace_test_recursion_unlock(bit);

}



#endif /* CONFIG_FUNCTION_GRAPH_TRACER */

arch/s390/kernel/mcount.S

+0 −11
Original line number Diff line number Diff line
@@ -104,17 +104,6 @@ SYM_CODE_START(ftrace_common) 
	lgr	%r3,%r14

	la	%r5,STACK_FREGS(%r15)

	BASR_EX	%r14,%r1

#ifdef CONFIG_FUNCTION_GRAPH_TRACER

# The j instruction gets runtime patched to a nop instruction.

# See ftrace_enable_ftrace_graph_caller.

SYM_INNER_LABEL(ftrace_graph_caller, SYM_L_GLOBAL)

	j	.Lftrace_graph_caller_end

	lmg	%r2,%r3,(STACK_FREGS_PTREGS_GPRS+14*8)(%r15)

	lg	%r4,(STACK_FREGS_PTREGS_PSW+8)(%r15)

	brasl	%r14,prepare_ftrace_return

	stg	%r2,(STACK_FREGS_PTREGS_GPRS+14*8)(%r15)

.Lftrace_graph_caller_end:

#endif

	lg	%r0,(STACK_FREGS_PTREGS_PSW+8)(%r15)

#ifdef MARCH_HAS_Z196_FEATURES

	ltg	%r1,STACK_FREGS_PTREGS_ORIG_GPR2(%r15)