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Commit f959196c authored by Palmer Dabbelt's avatar Palmer Dabbelt Committed by Greg Kroah-Hartman
Browse files

RISC-V: Take text_mutex in ftrace_init_nop() 



[ Upstream commit 66d18dbda8469a944dfec6c49d26d5946efba218 ]

Without this we get lockdep failures.  They're spurious failures as SMP isn't
up when ftrace_init_nop() is called.  As far as I can tell the easiest fix is
to just take the lock, which also seems like the safest fix.

Signed-off-by: default avatarPalmer Dabbelt <palmerdabbelt@google.com>
Acked-by: default avatarGuo Ren <guoren@kernel.org>
Signed-off-by: default avatarPalmer Dabbelt <palmerdabbelt@google.com>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 66dc1945

arch/riscv/include/asm/ftrace.h

+7 −0
Original line number Diff line number Diff line
@@ -63,4 +63,11 @@ do { \ 
 * Let auipc+jalr be the basic *mcount unit*, so we make it 8 bytes here.

 */

#define MCOUNT_INSN_SIZE 8



#ifndef __ASSEMBLY__

struct dyn_ftrace;

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

#define ftrace_init_nop ftrace_init_nop

#endif



#endif

arch/riscv/kernel/ftrace.c

+19 −0
Original line number Diff line number Diff line
@@ -88,6 +88,25 @@ int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, 
	return __ftrace_modify_call(rec->ip, addr, false);

}





/*

 * This is called early on, and isn't wrapped by

 * ftrace_arch_code_modify_{prepare,post_process}() and therefor doesn't hold

 * text_mutex, which triggers a lockdep failure.  SMP isn't running so we could

 * just directly poke the text, but it's simpler to just take the lock

 * ourselves.

 */

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

{

	int out;



	ftrace_arch_code_modify_prepare();

	out = ftrace_make_nop(mod, rec, MCOUNT_ADDR);

	ftrace_arch_code_modify_post_process();



	return out;

}



int ftrace_update_ftrace_func(ftrace_func_t func)

{

	int ret = __ftrace_modify_call((unsigned long)&ftrace_call,