Re: [RFC][PATCH 2/2] tracing/x86: basic implementation of syscalltracing for x86-64
From: Mathieu Desnoyers
Date: Fri Mar 13 2009 - 12:35:45 EST
* Frederic Weisbecker (fweisbec@xxxxxxxxx) wrote:
> Provide the ptrace hooks and arch specific syscall numbers to ftrace arch indepedant
> syscall numbers.
> For now it only supports 4 syscalls to provide an example.
>
Hi Frederic,
I already have the equivalent TIF_KERNEL_TRACE flag in my LTTng tree
added to every Linux architecture. You might want to re-use this work
rather than re-doing this. I don't mind changing the flag name.
Please see the LTTng tree and patchset at http://www.lttng.org. I'll
answer more precisely if you need more information.
Mathieu
> Signed-off-by: Frederic Weisbecker <fweisbec@xxxxxxxxx>
> ---
> arch/x86/Kconfig | 1 +
> arch/x86/include/asm/ftrace.h | 7 +++++++
> arch/x86/include/asm/thread_info.h | 9 ++++++---
> arch/x86/kernel/ftrace.c | 15 +++++++++++++++
> arch/x86/kernel/ptrace.c | 7 +++++++
> 5 files changed, 36 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 2a0ddfe..b5aec1b 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -35,6 +35,7 @@ config X86
> select HAVE_FUNCTION_GRAPH_TRACER
> select HAVE_FUNCTION_TRACE_MCOUNT_TEST
> select HAVE_FTRACE_NMI_ENTER if DYNAMIC_FTRACE
> + select HAVE_FTRACE_SYSCALLS if X86_64
> select HAVE_KVM
> select HAVE_ARCH_KGDB
> select HAVE_ARCH_TRACEHOOK
> diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
> index db24c22..b2e6855 100644
> --- a/arch/x86/include/asm/ftrace.h
> +++ b/arch/x86/include/asm/ftrace.h
> @@ -28,6 +28,13 @@
>
> #endif
>
> +/* FIXME: I don't want to stay hardcoded */
> +#ifdef CONFIG_X86_64
> +#define FTRACE_SYSCALL_MAX 296
> +#else
> +#define FTRACE_SYSCALL_MAX 333
> +#endif
> +
> #ifdef CONFIG_FUNCTION_TRACER
> #define MCOUNT_ADDR ((long)(mcount))
> #define MCOUNT_INSN_SIZE 5 /* sizeof mcount call */
> diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h
> index f6ba6f8..83d2b73 100644
> --- a/arch/x86/include/asm/thread_info.h
> +++ b/arch/x86/include/asm/thread_info.h
> @@ -95,6 +95,7 @@ struct thread_info {
> #define TIF_FORCED_TF 24 /* true if TF in eflags artificially */
> #define TIF_DEBUGCTLMSR 25 /* uses thread_struct.debugctlmsr */
> #define TIF_DS_AREA_MSR 26 /* uses thread_struct.ds_area_msr */
> +#define TIF_SYSCALL_FTRACE 27 /* for ftrace syscall instrumentation */
>
> #define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
> #define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
> @@ -117,15 +118,17 @@ struct thread_info {
> #define _TIF_FORCED_TF (1 << TIF_FORCED_TF)
> #define _TIF_DEBUGCTLMSR (1 << TIF_DEBUGCTLMSR)
> #define _TIF_DS_AREA_MSR (1 << TIF_DS_AREA_MSR)
> +#define _TIF_SYSCALL_FTRACE (1 << TIF_SYSCALL_FTRACE)
>
> /* work to do in syscall_trace_enter() */
> #define _TIF_WORK_SYSCALL_ENTRY \
> - (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU | \
> + (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU | _TIF_SYSCALL_FTRACE | \
> _TIF_SYSCALL_AUDIT | _TIF_SECCOMP | _TIF_SINGLESTEP)
>
> /* work to do in syscall_trace_leave() */
> #define _TIF_WORK_SYSCALL_EXIT \
> - (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | _TIF_SINGLESTEP)
> + (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | _TIF_SINGLESTEP | \
> + _TIF_SYSCALL_FTRACE)
>
> /* work to do on interrupt/exception return */
> #define _TIF_WORK_MASK \
> @@ -134,7 +137,7 @@ struct thread_info {
> _TIF_SINGLESTEP|_TIF_SECCOMP|_TIF_SYSCALL_EMU))
>
> /* work to do on any return to user space */
> -#define _TIF_ALLWORK_MASK (0x0000FFFF & ~_TIF_SECCOMP)
> +#define _TIF_ALLWORK_MASK ((0x0000FFFF & ~_TIF_SECCOMP) | _TIF_SYSCALL_FTRACE)
>
> /* Only used for 64 bit */
> #define _TIF_DO_NOTIFY_MASK \
> diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
> index a85da17..5bba98b 100644
> --- a/arch/x86/kernel/ftrace.c
> +++ b/arch/x86/kernel/ftrace.c
> @@ -453,3 +453,18 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)
> }
> }
> #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
> +
> +#ifdef CONFIG_FTRACE_SYSCALLS
> +#ifdef CONFIG_X86_64
> +/*
> + * Array that make the arch specific syscall numbers
> + * matching the ftrace syscall numbers.
> + */
> +short arch_syscall_trace_nr[FTRACE_SYSCALL_MAX] = {
> + [__NR_open] = SYSCALL_TRACE_OPEN,
> + [__NR_close] = SYSCALL_TRACE_CLOSE,
> + [__NR_read] = SYSCALL_TRACE_READ,
> + [__NR_write] = SYSCALL_TRACE_WRITE
> +};
> +#endif
> +#endif
> diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
> index 3d9672e..99749d6 100644
> --- a/arch/x86/kernel/ptrace.c
> +++ b/arch/x86/kernel/ptrace.c
> @@ -21,6 +21,7 @@
> #include <linux/audit.h>
> #include <linux/seccomp.h>
> #include <linux/signal.h>
> +#include <linux/ftrace.h>
>
> #include <asm/uaccess.h>
> #include <asm/pgtable.h>
> @@ -1416,6 +1417,9 @@ asmregparm long syscall_trace_enter(struct pt_regs *regs)
> tracehook_report_syscall_entry(regs))
> ret = -1L;
>
> + if (unlikely(test_thread_flag(TIF_SYSCALL_FTRACE)))
> + ftrace_syscall_enter(regs);
> +
> if (unlikely(current->audit_context)) {
> if (IS_IA32)
> audit_syscall_entry(AUDIT_ARCH_I386,
> @@ -1439,6 +1443,9 @@ asmregparm void syscall_trace_leave(struct pt_regs *regs)
> if (unlikely(current->audit_context))
> audit_syscall_exit(AUDITSC_RESULT(regs->ax), regs->ax);
>
> + if (unlikely(test_thread_flag(TIF_SYSCALL_FTRACE)))
> + ftrace_syscall_exit(regs);
> +
> if (test_thread_flag(TIF_SYSCALL_TRACE))
> tracehook_report_syscall_exit(regs, 0);
>
> --
> 1.6.1
>
--
Mathieu Desnoyers
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
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