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Commit 88a7c26a authored by Andy Lutomirski's avatar Andy Lutomirski Committed by Ingo Molnar
Browse files

perf: Move task_pt_regs sampling into arch code 



On x86_64, at least, task_pt_regs may be only partially initialized
in many contexts, so x86_64 should not use it without extra care
from interrupt context, let alone NMI context.

This will allow x86_64 to override the logic and will supply some
scratch space to use to make a cleaner copy of user regs.

Tested-by: default avatarJiri Olsa <jolsa@kernel.org>
Signed-off-by: default avatarAndy Lutomirski <luto@amacapital.net>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: chenggang.qcg@taobao.com
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Jean Pihet <jean.pihet@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Salter <msalter@redhat.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Will Deacon <will.deacon@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/e431cd4c18c2e1c44c774f10758527fb2d1025c4.1420396372.git.luto@amacapital.net


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 0f363b25

arch/arm/kernel/perf_regs.c

+8 −0
Original line number Diff line number Diff line
@@ -28,3 +28,11 @@ u64 perf_reg_abi(struct task_struct *task) 
{

	return PERF_SAMPLE_REGS_ABI_32;

}



void perf_get_regs_user(struct perf_regs *regs_user,

			struct pt_regs *regs,

			struct pt_regs *regs_user_copy)

{

	regs_user->regs = task_pt_regs(current);

	regs_user->abi = perf_reg_abi(current);

}

arch/arm64/kernel/perf_regs.c

+8 −0
Original line number Diff line number Diff line
@@ -50,3 +50,11 @@ u64 perf_reg_abi(struct task_struct *task) 
	else

		return PERF_SAMPLE_REGS_ABI_64;

}



void perf_get_regs_user(struct perf_regs *regs_user,

			struct pt_regs *regs,

			struct pt_regs *regs_user_copy)

{

	regs_user->regs = task_pt_regs(current);

	regs_user->abi = perf_reg_abi(current);

}

arch/x86/kernel/perf_regs.c

+16 −0
Original line number Diff line number Diff line
@@ -78,6 +78,14 @@ u64 perf_reg_abi(struct task_struct *task) 
{

	return PERF_SAMPLE_REGS_ABI_32;

}



void perf_get_regs_user(struct perf_regs *regs_user,

			struct pt_regs *regs,

			struct pt_regs *regs_user_copy)

{

	regs_user->regs = task_pt_regs(current);

	regs_user->abi = perf_reg_abi(current);

}

#else /* CONFIG_X86_64 */

#define REG_NOSUPPORT ((1ULL << PERF_REG_X86_DS) | \

		       (1ULL << PERF_REG_X86_ES) | \
@@ -102,4 +110,12 @@ u64 perf_reg_abi(struct task_struct *task) 
	else

		return PERF_SAMPLE_REGS_ABI_64;

}



void perf_get_regs_user(struct perf_regs *regs_user,

			struct pt_regs *regs,

			struct pt_regs *regs_user_copy)

{

	regs_user->regs = task_pt_regs(current);

	regs_user->abi = perf_reg_abi(current);

}

#endif /* CONFIG_X86_32 */

include/linux/perf_event.h

+7 −5
Original line number Diff line number Diff line
@@ -79,11 +79,6 @@ struct perf_branch_stack { 
	struct perf_branch_entry	entries[0];

};



struct perf_regs {

	__u64		abi;

	struct pt_regs	*regs;

};



struct task_struct;



/*
@@ -610,7 +605,14 @@ struct perf_sample_data { 
		u32	reserved;

	}				cpu_entry;

	struct perf_callchain_entry	*callchain;



	/*

	 * regs_user may point to task_pt_regs or to regs_user_copy, depending

	 * on arch details.

	 */

	struct perf_regs		regs_user;

	struct pt_regs			regs_user_copy;



	struct perf_regs		regs_intr;

	u64				stack_user_size;

} ____cacheline_aligned;

include/linux/perf_regs.h

+16 −0
Original line number Diff line number Diff line 
#ifndef _LINUX_PERF_REGS_H

#define _LINUX_PERF_REGS_H



struct perf_regs {

	__u64		abi;

	struct pt_regs	*regs;

};



#ifdef CONFIG_HAVE_PERF_REGS

#include <asm/perf_regs.h>

u64 perf_reg_value(struct pt_regs *regs, int idx);

int perf_reg_validate(u64 mask);

u64 perf_reg_abi(struct task_struct *task);

void perf_get_regs_user(struct perf_regs *regs_user,

			struct pt_regs *regs,

			struct pt_regs *regs_user_copy);

#else

static inline u64 perf_reg_value(struct pt_regs *regs, int idx)

{
@@ -21,5 +29,13 @@ static inline u64 perf_reg_abi(struct task_struct *task) 
{

	return PERF_SAMPLE_REGS_ABI_NONE;

}



static inline void perf_get_regs_user(struct perf_regs *regs_user,

				      struct pt_regs *regs,

				      struct pt_regs *regs_user_copy)

{

	regs_user->regs = task_pt_regs(current);

	regs_user->abi = perf_reg_abi(current);

}

#endif /* CONFIG_HAVE_PERF_REGS */

#endif /* _LINUX_PERF_REGS_H */