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arm64: ftrace: Add system call tracepoint

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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: Will Deacon <will.deacon@arm.com>
Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
AKASHI Takahiro 2014-04-30 10:54:36 +01:00 committed by Will Deacon
parent 3711784ece
commit 055b1212d1
5 changed files with 31 additions and 0 deletions
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1
arch/arm64/Kconfig
View File

@ -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

18
arch/arm64/include/asm/ftrace.h
View File

@ -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 */

1
arch/arm64/include/asm/syscall.h
View File

@ -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)

2
arch/arm64/include/asm/unistd.h
View File

@ -29,3 +29,5 @@
#endif
#define __ARCH_WANT_SYS_CLONE
#include <uapi/asm/unistd.h>
#define NR_syscalls (__NR_syscalls)

9
arch/arm64/kernel/ptrace.c
View File

@ -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);
}