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Subject[PATCH v3] mips specific system call tracer
Date
From: Wu Zhangjin <wuzj@lemote.com>

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@lemote.com>
---
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 5ac9f45..a4a5af5 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@lemote.com>
+ *
+ * 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 44ec7e0..1114c85 100644
--- a/arch/mips/kernel/Makefile
+++ b/arch/mips/kernel/Makefile
@@ -33,6 +33,7 @@ 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 65d4d56..c83b586 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 */
@@ -271,3 +273,72 @@ unsigned long prepare_ftrace_return(unsigned long ip,
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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