Re: [PATCH v1 5/5] mips specific system call tracer

From: Steven Rostedt
Date: Thu May 28 2009 - 22:09:34 EST


Since Frederic did the x86 version, I just added him to the Cc here.

-- Steve


On Fri, 29 May 2009, wuzhangjin@xxxxxxxxx wrote:

> From: Wu Zhangjin <wuzj@xxxxxxxxxx>
>
> FIXME: there are several different sys_call_entry in mips64, but
> currently, i only use the the one in arch/mips/kernel/scall64-o32.S
> so,if people not use o32 standard, it will not compiled normally.
>
> the system call tracing demo in a debian system on
> qemu-system-mipsel/malta:
>
> debian-mips-malta:~# mount -t debugfs nodev /debug
> debian-mips-malta:~# echo 20000 > /debug/tracing/buffer_size_kb
> debian-mips-malta:~# cat /debug/tracing/available_tracers
> syscall nop
> debian-mips-malta:~# echo syscall > /debug/tracing/current_tracer
> debian-mips-malta:~# echo 1 > /debug/tracing/tracing_enabled
> debian-mips-malta:~# sleep 1
> debian-mips-malta:~# echo 0 > /debug/tracing/tracing_enabled
> debian-mips-malta:~# cat /debug/tracing/trace | head -20
> <...>-533 [000] 60.458291: sys_write(fd: 1, buf: 4fc408, count: 8)
> <...>-533 [000] 64.325614: sys_getrlimit(resource: 3, rlim: 530020)
> <...>-533 [000] 64.327089: sys_read(fd: 2, buf: 4fc008, count: 6)
> <...>-533 [000] 64.969663: sys_exit(error_code: 2)
> <...>-533 [000] 65.608794: sys_exit(error_code: 2)
> <...>-533 [000] 66.231796: sys_read(fd: 2, buf: 4fc008, count: 6)
> <...>-533 [000] 66.913687: sys_open(filename: 1, flags: 0, mode: a)
> <...>-533 [000] 66.914617: sys_exit(error_code: 1)
> <...>-533 [000] 70.797507: sys_exit(error_code: 503be8)
> <...>-536 [000] 70.833108: sys_exit(error_code: 2aac6cfc)
> <...>-536 [000] 70.833897: sys_exit(error_code: 2aac6540)
> <...>-536 [000] 70.835711: sys_exit(error_code: 2aac6cfc)
> <...>-536 [000] 70.840609: sys_lchown(filename: 3, user: 7fb08b38, group: 20)
> <...>-533 [000] 71.877785: sys_open(filename: ffffffff, flags: 7fcf08c8, mode: b)
> <...>-533 [000] 75.531122: sys_open(filename: 1, flags: 0, mode: a)
>
> Signed-off-by: Wu Zhangjin <wuzj@xxxxxxxxxx>
> ---
> arch/mips/Kconfig | 1 +
> arch/mips/include/asm/ptrace.h | 2 +
> arch/mips/include/asm/reg.h | 5 ++
> arch/mips/include/asm/syscall.h | 84 +++++++++++++++++++++++++++++++++++
> arch/mips/include/asm/thread_info.h | 5 ++-
> arch/mips/kernel/Makefile | 1 +
> arch/mips/kernel/entry.S | 2 +-
> arch/mips/kernel/ftrace.c | 71 +++++++++++++++++++++++++++++
> arch/mips/kernel/ptrace.c | 14 +++++-
> arch/mips/kernel/scall64-o32.S | 2 +-
> 10 files changed, 182 insertions(+), 5 deletions(-)
> create mode 100644 arch/mips/include/asm/syscall.h
>
> diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
> index ac1437e..f488027 100644
> --- a/arch/mips/Kconfig
> +++ b/arch/mips/Kconfig
> @@ -10,6 +10,7 @@ config MIPS
> select HAVE_FTRACE_MCOUNT_RECORD
> select HAVE_FTRACE_NMI_ENTER if DYNAMIC_FTRACE
> select HAVE_FUNCTION_GRAPH_TRACER
> + select HAVE_FTRACE_SYSCALLS
> # Horrible source of confusion. Die, die, die ...
> select EMBEDDED
> select RTC_LIB
> diff --git a/arch/mips/include/asm/ptrace.h b/arch/mips/include/asm/ptrace.h
> index ce47118..32e5b62 100644
> --- a/arch/mips/include/asm/ptrace.h
> +++ b/arch/mips/include/asm/ptrace.h
> @@ -45,6 +45,8 @@ struct pt_regs {
> unsigned long cp0_badvaddr;
> unsigned long cp0_cause;
> unsigned long cp0_epc;
> + /* Used for restarting system calls */
> + unsigned long orig_v0;
> #ifdef CONFIG_MIPS_MT_SMTC
> unsigned long cp0_tcstatus;
> #endif /* CONFIG_MIPS_MT_SMTC */
> diff --git a/arch/mips/include/asm/reg.h b/arch/mips/include/asm/reg.h
> index 634b55d..93d66bc 100644
> --- a/arch/mips/include/asm/reg.h
> +++ b/arch/mips/include/asm/reg.h
> @@ -65,6 +65,8 @@
> #define EF_CP0_CAUSE 43
> #define EF_UNUSED0 44
>
> +#define EF_ORIG_V0 45
> +
> #define EF_SIZE 180
>
> #endif
> @@ -121,6 +123,9 @@
> #define EF_CP0_STATUS 36
> #define EF_CP0_CAUSE 37
>
> +
> +#define EF_ORIG_V0 38
> +
> #define EF_SIZE 304 /* size in bytes */
>
> #endif /* CONFIG_64BIT */
> diff --git a/arch/mips/include/asm/syscall.h b/arch/mips/include/asm/syscall.h
> new file mode 100644
> index 0000000..b785098
> --- /dev/null
> +++ b/arch/mips/include/asm/syscall.h
> @@ -0,0 +1,84 @@
> +/*
> + * Access to user system call parameters and results
> + *
> + * Copyright (C) 2008 Red Hat, Inc. All rights reserved.
> + * Copyright (C) 2009 DSLab, Lanzhou University, China
> + * Author: Wu Zhangjin <wuzj@xxxxxxxxxx>
> + *
> + * This copyrighted material is made available to anyone wishing to use,
> + * modify, copy, or redistribute it subject to the terms and conditions
> + * of the GNU General Public License v.2.
> + *
> + * See asm-generic/syscall.h for descriptions of what we must do here.
> + */
> +
> +#ifndef _ASM_SYSCALL_H
> +#define _ASM_SYSCALL_H 1
> +
> +#include <linux/sched.h>
> +
> +static inline long syscall_get_nr(struct task_struct *task,
> + struct pt_regs *regs)
> +{
> + /* syscall Exc-Code: 0 1000 00 v0 */
> + return ((regs->cp0_cause&0xff) == 0x20) ? regs->regs[2] : -1L;
> +}
> +
> +static inline void syscall_rollback(struct task_struct *task,
> + struct pt_regs *regs)
> +{
> + regs->regs[2] = regs->orig_v0;
> +}
> +
> +static inline long syscall_get_error(struct task_struct *task,
> + struct pt_regs *regs)
> +{
> + return regs->regs[2] ? -regs->regs[2] : 0;
> +}
> +
> +static inline long syscall_get_return_value(struct task_struct *task,
> + struct pt_regs *regs)
> +{
> + return regs->regs[2];
> +}
> +
> +static inline void syscall_set_return_value(struct task_struct *task,
> + struct pt_regs *regs,
> + int error, long val)
> +{
> + if (error)
> + regs->regs[2] = -error;
> + else
> + regs->regs[2] = val;
> +}
> +
> +static inline void syscall_get_arguments(struct task_struct *task,
> + struct pt_regs *regs,
> + unsigned int i, unsigned int n,
> + unsigned long *args)
> +{
> +#ifdef CONFIG_32BIT
> + /* fixme: only 4 argument register available in mip32, so, how to handle
> + * others?
> + */
> + BUG_ON(i + n > 4);
> +#else
> + BUG_ON(i + n > 6);
> +#endif
> + memcpy(args, &regs->regs[4 + i], n * sizeof(args[0]));
> +}
> +
> +static inline void syscall_set_arguments(struct task_struct *task,
> + struct pt_regs *regs,
> + unsigned int i, unsigned int n,
> + const unsigned long *args)
> +{
> +#ifdef CONFIG_32BIT
> + BUG_ON(i + n > 4);
> +#else
> + BUG_ON(i + n > 6);
> +#endif
> + memcpy(&regs->regs[4 + i], args, n * sizeof(args[0]));
> +}
> +
> +#endif /* _ASM_SYSCALL_H */
> diff --git a/arch/mips/include/asm/thread_info.h b/arch/mips/include/asm/thread_info.h
> index 143a481..1d55dc0 100644
> --- a/arch/mips/include/asm/thread_info.h
> +++ b/arch/mips/include/asm/thread_info.h
> @@ -128,6 +128,7 @@ register struct thread_info *__current_thread_info __asm__("$28");
> #define TIF_32BIT_ADDR 23 /* 32-bit address space (o32/n32) */
> #define TIF_FPUBOUND 24 /* thread bound to FPU-full CPU set */
> #define TIF_LOAD_WATCH 25 /* If set, load watch registers */
> +#define TIF_SYSCALL_FTRACE 27 /* for ftrace syscall instrumentation */
> #define TIF_SYSCALL_TRACE 31 /* syscall trace active */
>
> #ifdef CONFIG_MIPS32_O32
> @@ -151,11 +152,13 @@ register struct thread_info *__current_thread_info __asm__("$28");
> #define _TIF_32BIT_ADDR (1<<TIF_32BIT_ADDR)
> #define _TIF_FPUBOUND (1<<TIF_FPUBOUND)
> #define _TIF_LOAD_WATCH (1<<TIF_LOAD_WATCH)
> +#define _TIF_SYSCALL_FTRACE (1<<TIF_SYSCALL_FTRACE)
>
> /* work to do on interrupt/exception return */
> #define _TIF_WORK_MASK (0x0000ffef & ~_TIF_SECCOMP)
> /* work to do on any return to u-space */
> -#define _TIF_ALLWORK_MASK (0x8000ffff & ~_TIF_SECCOMP)
> +#define _TIF_ALLWORK_MASK \
> + ((0x8000ffff & ~_TIF_SECCOMP) | _TIF_SYSCALL_FTRACE)
>
> #endif /* __KERNEL__ */
>
> diff --git a/arch/mips/kernel/Makefile b/arch/mips/kernel/Makefile
> index 5dec76f..8b4fafa 100644
> --- a/arch/mips/kernel/Makefile
> +++ b/arch/mips/kernel/Makefile
> @@ -34,6 +34,7 @@ obj-$(CONFIG_MODULES) += mips_ksyms.o module.o
>
> obj-$(CONFIG_FUNCTION_TRACER) += mcount.o
> obj-$(CONFIG_FUNCTION_TRACER) += ftrace.o
> +obj-$(CONFIG_FTRACE_SYSCALLS) += ftrace.o
> obj-$(CONFIG_NOP_TRACER) += ftrace_clock.o
>
> obj-$(CONFIG_CPU_LOONGSON2) += r4k_fpu.o r4k_switch.o
> diff --git a/arch/mips/kernel/entry.S b/arch/mips/kernel/entry.S
> index ffa3310..786e4ef 100644
> --- a/arch/mips/kernel/entry.S
> +++ b/arch/mips/kernel/entry.S
> @@ -167,7 +167,7 @@ work_notifysig: # deal with pending signals and
> FEXPORT(syscall_exit_work_partial)
> SAVE_STATIC
> syscall_exit_work:
> - li t0, _TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT
> + li t0, _TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | _TIF_SYSCALL_FTRACE
> and t0, a2 # a2 is preloaded with TI_FLAGS
> beqz t0, work_pending # trace bit set?
> local_irq_enable # could let do_syscall_trace()
> diff --git a/arch/mips/kernel/ftrace.c b/arch/mips/kernel/ftrace.c
> index e7f15f7..5967998 100644
> --- a/arch/mips/kernel/ftrace.c
> +++ b/arch/mips/kernel/ftrace.c
> @@ -22,6 +22,8 @@
> #include <asm/asm.h>
> #include <asm/unistd.h>
>
> +#include <trace/syscall.h>
> +
> #ifdef CONFIG_DYNAMIC_FTRACE
>
> #define JAL 0x0c000000 /* jump & link: ip --> ra, jump to target */
> @@ -287,3 +289,72 @@ out:
> return parent_ip;
> }
> #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
> +
> +#ifdef CONFIG_FTRACE_SYSCALLS
> +
> +extern unsigned long __start_syscalls_metadata[];
> +extern unsigned long __stop_syscalls_metadata[];
> +
> +/* fixme: in mips64, there are different entries of sys_call_table when using
> + * different standards, in loongson2f based machines: Fuloong & Yeeloong, the
> + * system use o32 standard, so here, we only use the sys_call_table in
> + * arch/mips/kernel/scall64-o32.S */
> +
> +extern unsigned long *sys_call_table;
> +
> +static struct syscall_metadata **syscalls_metadata;
> +
> +static struct syscall_metadata *find_syscall_meta(unsigned long *syscall)
> +{
> + struct syscall_metadata *start;
> + struct syscall_metadata *stop;
> + char str[KSYM_SYMBOL_LEN];
> +
> +
> + start = (struct syscall_metadata *)__start_syscalls_metadata;
> + stop = (struct syscall_metadata *)__stop_syscalls_metadata;
> + kallsyms_lookup((unsigned long) syscall, NULL, NULL, NULL, str);
> +
> + for ( ; start < stop; start++) {
> + if (start->name && !strcmp(start->name, str))
> + return start;
> + }
> + return NULL;
> +}
> +
> +struct syscall_metadata *syscall_nr_to_meta(int nr)
> +{
> + if (!syscalls_metadata || nr >= __NR_Linux_syscalls || nr < 0)
> + return NULL;
> +
> + return syscalls_metadata[nr];
> +}
> +
> +void arch_init_ftrace_syscalls(void)
> +{
> + int i;
> + struct syscall_metadata *meta;
> + unsigned long **psys_syscall_table = &sys_call_table;
> + static atomic_t refs;
> +
> + if (atomic_inc_return(&refs) != 1)
> + goto end;
> +
> + syscalls_metadata = kzalloc(sizeof(*syscalls_metadata) *
> + __NR_Linux_syscalls, GFP_KERNEL);
> + if (!syscalls_metadata) {
> + WARN_ON(1);
> + return;
> + }
> +
> + for (i = 0; i < __NR_Linux_syscalls; i++) {
> + meta = find_syscall_meta(psys_syscall_table[i]);
> + syscalls_metadata[i] = meta;
> + }
> + return;
> +
> + /* Paranoid: avoid overflow */
> +end:
> + atomic_dec(&refs);
> +}
> +#endif /* CONFIG_FTRACE_SYSCALLS */
> diff --git a/arch/mips/kernel/ptrace.c b/arch/mips/kernel/ptrace.c
> index 054861c..fa762dc 100644
> --- a/arch/mips/kernel/ptrace.c
> +++ b/arch/mips/kernel/ptrace.c
> @@ -25,6 +25,7 @@
> #include <linux/security.h>
> #include <linux/audit.h>
> #include <linux/seccomp.h>
> +#include <linux/ftrace.h>
>
> #include <asm/byteorder.h>
> #include <asm/cpu.h>
> @@ -39,6 +40,7 @@
> #include <asm/bootinfo.h>
> #include <asm/reg.h>
>
> +#include <trace/syscall.h>
> /*
> * Called by kernel/ptrace.c when detaching..
> *
> @@ -60,7 +62,7 @@ int ptrace_getregs(struct task_struct *child, __s64 __user *data)
> struct pt_regs *regs;
> int i;
>
> - if (!access_ok(VERIFY_WRITE, data, 38 * 8))
> + if (!access_ok(VERIFY_WRITE, data, 39 * 8))
> return -EIO;
>
> regs = task_pt_regs(child);
> @@ -73,6 +75,7 @@ int ptrace_getregs(struct task_struct *child, __s64 __user *data)
> __put_user((long)regs->cp0_badvaddr, data + EF_CP0_BADVADDR - EF_R0);
> __put_user((long)regs->cp0_status, data + EF_CP0_STATUS - EF_R0);
> __put_user((long)regs->cp0_cause, data + EF_CP0_CAUSE - EF_R0);
> + __put_user((long)regs->orig_v0, data + EF_ORIG_V0 - EF_R0);
>
> return 0;
> }
> @@ -87,7 +90,7 @@ int ptrace_setregs(struct task_struct *child, __s64 __user *data)
> struct pt_regs *regs;
> int i;
>
> - if (!access_ok(VERIFY_READ, data, 38 * 8))
> + if (!access_ok(VERIFY_READ, data, 39 * 8))
> return -EIO;
>
> regs = task_pt_regs(child);
> @@ -97,6 +100,7 @@ int ptrace_setregs(struct task_struct *child, __s64 __user *data)
> __get_user(regs->lo, data + EF_LO - EF_R0);
> __get_user(regs->hi, data + EF_HI - EF_R0);
> __get_user(regs->cp0_epc, data + EF_CP0_EPC - EF_R0);
> + __get_user(regs->orig_v0, data + EF_ORIG_V0 - EF_R0);
>
> /* badvaddr, status, and cause may not be written. */
>
> @@ -575,6 +579,9 @@ asmlinkage void do_syscall_trace(struct pt_regs *regs, int entryexit)
> if (!(current->ptrace & PT_PTRACED))
> goto out;
>
> + if (unlikely(test_thread_flag(TIF_SYSCALL_FTRACE)))
> + ftrace_syscall_exit(regs);
> +
> if (!test_thread_flag(TIF_SYSCALL_TRACE))
> goto out;
>
> @@ -594,6 +601,9 @@ asmlinkage void do_syscall_trace(struct pt_regs *regs, int entryexit)
> }
>
> out:
> + if (unlikely(test_thread_flag(TIF_SYSCALL_FTRACE)))
> + ftrace_syscall_enter(regs);
> +
> if (unlikely(current->audit_context) && !entryexit)
> audit_syscall_entry(audit_arch(), regs->regs[0],
> regs->regs[4], regs->regs[5],
> diff --git a/arch/mips/kernel/scall64-o32.S b/arch/mips/kernel/scall64-o32.S
> index a5598b2..dd1f13a 100644
> --- a/arch/mips/kernel/scall64-o32.S
> +++ b/arch/mips/kernel/scall64-o32.S
> @@ -202,7 +202,7 @@ einval: li v0, -ENOSYS
>
> .align 3
> .type sys_call_table,@object
> -sys_call_table:
> +EXPORT(sys_call_table)
> PTR sys32_syscall /* 4000 */
> PTR sys_exit
> PTR sys_fork
> --
> 1.6.0.4
>
>
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