Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 5000653e authored by Tony Wu's avatar Tony Wu Committed by Ralf Baechle
Browse files

MIPS: Extract schedule_mfi info from __schedule 



schedule_mfi is supposed to be extracted from schedule(), and
is used in thread_saved_pc and get_wchan.

But, after optimization, schedule() is reduced to a sibling
call to __schedule(), and no real frame info can be extracted.

One solution is to compile schedule() with -fno-omit-frame-pointer
and -fno-optimize-sibling-calls, but that will incur performance
degradation.

Another solution is to extract info from the real scheduler,
__schedule, and this is the approache adopted here.

This patch reads the __schedule address by either following
the 'j' call in schedule if KALLSYMS is disabled or by using
kallsyms_lookup_name to lookup __schedule if KALLSYMS is
available, then, extracts schedule_mfi from __schedule frame info.

This patch also fixes the "Can't analyze schedule() prologue"
warning at boot time.

Signed-off-by: default avatarTony Wu <tung7970@gmail.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/5237/


Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent e7438c4b

arch/mips/kernel/process.c

+32 −2
Original line number Original line Diff line number Diff line
@@ -224,6 +224,9 @@ struct mips_frame_info { 
	int		pc_offset;

	int		pc_offset;

};

};





#define J_TARGET(pc,target)	\

		(((unsigned long)(pc) & 0xf0000000) | ((target) << 2))



static inline int is_ra_save_ins(union mips_instruction *ip)

static inline int is_ra_save_ins(union mips_instruction *ip)

{

{

#ifdef CONFIG_CPU_MICROMIPS

#ifdef CONFIG_CPU_MICROMIPS
@@ -395,15 +398,42 @@ static int get_frame_info(struct mips_frame_info *info) 




static struct mips_frame_info schedule_mfi __read_mostly;

static struct mips_frame_info schedule_mfi __read_mostly;





#ifdef CONFIG_KALLSYMS

static unsigned long get___schedule_addr(void)

{

	return kallsyms_lookup_name("__schedule");

}

#else

static unsigned long get___schedule_addr(void)

{

	union mips_instruction *ip = (void *)schedule;

	int max_insns = 8;

	int i;



	for (i = 0; i < max_insns; i++, ip++) {

		if (ip->j_format.opcode == j_op)

			return J_TARGET(ip, ip->j_format.target);

	}

	return 0;

}

#endif



static int __init frame_info_init(void)

static int __init frame_info_init(void)

{

{

	unsigned long size = 0;

	unsigned long size = 0;

#ifdef CONFIG_KALLSYMS

#ifdef CONFIG_KALLSYMS

	unsigned long ofs;

	unsigned long ofs;

#endif

	unsigned long addr;





	kallsyms_lookup_size_offset((unsigned long)schedule, &size, &ofs);

	addr = get___schedule_addr();

	if (!addr)

		addr = (unsigned long)schedule;



#ifdef CONFIG_KALLSYMS

	kallsyms_lookup_size_offset(addr, &size, &ofs);

#endif

#endif

	schedule_mfi.func = schedule;

	schedule_mfi.func = (void *)addr;

	schedule_mfi.func_size = size;

	schedule_mfi.func_size = size;





	get_frame_info(&schedule_mfi);

	get_frame_info(&schedule_mfi);