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Commit 055b1212 authored by AKASHI Takahiro's avatar AKASHI Takahiro Committed by Will Deacon
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arm64: ftrace: Add system call tracepoint 



This patch allows system call entry or exit to be traced as ftrace events,
ie. sys_enter_*/sys_exit_*, if CONFIG_FTRACE_SYSCALLS is enabled.
Those events appear and can be controlled under
    ${sysfs}/tracing/events/syscalls/

Please note that we can't trace compat system calls here because
AArch32 mode does not share the same syscall table with AArch64.
Just define ARCH_TRACE_IGNORE_COMPAT_SYSCALLS in order to avoid unexpected
results (bogus syscalls reported or even hang-up).

Acked-by: default avatarWill Deacon <will.deacon@arm.com>
Signed-off-by: default avatarAKASHI Takahiro <takahiro.akashi@linaro.org>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent 3711784e

arch/arm64/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -48,6 +48,7 @@ config ARM64 
	select HAVE_PERF_EVENTS

	select HAVE_PERF_REGS

	select HAVE_PERF_USER_STACK_DUMP

	select HAVE_SYSCALL_TRACEPOINTS

	select IRQ_DOMAIN

	select MODULES_USE_ELF_RELA

	select NO_BOOTMEM

arch/arm64/include/asm/ftrace.h

+18 −0
Original line number Diff line number Diff line
@@ -17,6 +17,8 @@ 
#define MCOUNT_INSN_SIZE	AARCH64_INSN_SIZE



#ifndef __ASSEMBLY__

#include <linux/compat.h>



extern void _mcount(unsigned long);

extern void *return_address(unsigned int);
@@ -36,6 +38,22 @@ static inline unsigned long ftrace_call_adjust(unsigned long addr) 
}



#define ftrace_return_address(n) return_address(n)



/*

 * Because AArch32 mode does not share the same syscall table with AArch64,

 * tracing compat syscalls may result in reporting bogus syscalls or even

 * hang-up, so just do not trace them.

 * See kernel/trace/trace_syscalls.c

 *

 * x86 code says:

 * If the user realy wants these, then they should use the

 * raw syscall tracepoints with filtering.

 */

#define ARCH_TRACE_IGNORE_COMPAT_SYSCALLS

static inline bool arch_trace_is_compat_syscall(struct pt_regs *regs)

{

	return is_compat_task();

}

#endif /* ifndef __ASSEMBLY__ */



#endif /* __ASM_FTRACE_H */

arch/arm64/include/asm/syscall.h

+1 −0
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ 


#include <linux/err.h>



extern const void *sys_call_table[];



static inline int syscall_get_nr(struct task_struct *task,

				 struct pt_regs *regs)

arch/arm64/include/asm/unistd.h

+2 −0
Original line number Diff line number Diff line
@@ -29,3 +29,5 @@ 
#endif

#define __ARCH_WANT_SYS_CLONE

#include <uapi/asm/unistd.h>



#define NR_syscalls (__NR_syscalls)

arch/arm64/kernel/ptrace.c

+9 −0
Original line number Diff line number Diff line
@@ -42,6 +42,9 @@ 
#include <asm/traps.h>

#include <asm/system_misc.h>



#define CREATE_TRACE_POINTS

#include <trace/events/syscalls.h>



/*

 * TODO: does not yet catch signals sent when the child dies.

 * in exit.c or in signal.c.
@@ -1093,11 +1096,17 @@ asmlinkage int syscall_trace_enter(struct pt_regs *regs) 
	if (test_thread_flag(TIF_SYSCALL_TRACE))

		tracehook_report_syscall(regs, PTRACE_SYSCALL_ENTER);



	if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))

		trace_sys_enter(regs, regs->syscallno);



	return regs->syscallno;

}



asmlinkage void syscall_trace_exit(struct pt_regs *regs)

{

	if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))

		trace_sys_exit(regs, regs_return_value(regs));



	if (test_thread_flag(TIF_SYSCALL_TRACE))

		tracehook_report_syscall(regs, PTRACE_SYSCALL_EXIT);

}