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authorRoland McGrath <roland@redhat.com>2008-07-25 22:45:57 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2008-07-26 15:00:09 -0400
commit828c365cc8b8d38c346fccb19fa80d28f2240831 (patch)
treecedb0f1ce389f4b12d7b0975ce52c8af7939cfcd /include
parent64b1208d5b0ef8859fd52ea7ae286a3eb994669b (diff)
tracehook: asm/syscall.h
This adds asm-generic/syscall.h, which documents what a real asm-ARCH/syscall.h file should define. This is not used yet, but will provide all the machine-dependent details of examining a user system call about to begin, in progress, or just ended. Each arch should add an asm-ARCH/syscall.h that defines all the entry points documented in asm-generic/syscall.h, as short inlines if possible. This lets us write new tracing code that understands user system call registers, without any new arch-specific work. Signed-off-by: Roland McGrath <roland@redhat.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Reviewed-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/asm-generic/syscall.h141
-rw-r--r--include/linux/tracehook.h3
2 files changed, 143 insertions, 1 deletions
diff --git a/include/asm-generic/syscall.h b/include/asm-generic/syscall.h
new file mode 100644
index 000000000000..abcf34c2fdc7
--- /dev/null
+++ b/include/asm-generic/syscall.h
@@ -0,0 +1,141 @@
1/*
2 * Access to user system call parameters and results
3 *
4 * Copyright (C) 2008 Red Hat, Inc. All rights reserved.
5 *
6 * This copyrighted material is made available to anyone wishing to use,
7 * modify, copy, or redistribute it subject to the terms and conditions
8 * of the GNU General Public License v.2.
9 *
10 * This file is a stub providing documentation for what functions
11 * asm-ARCH/syscall.h files need to define. Most arch definitions
12 * will be simple inlines.
13 *
14 * All of these functions expect to be called with no locks,
15 * and only when the caller is sure that the task of interest
16 * cannot return to user mode while we are looking at it.
17 */
18
19#ifndef _ASM_SYSCALL_H
20#define _ASM_SYSCALL_H 1
21
22struct task_struct;
23struct pt_regs;
24
25/**
26 * syscall_get_nr - find what system call a task is executing
27 * @task: task of interest, must be blocked
28 * @regs: task_pt_regs() of @task
29 *
30 * If @task is executing a system call or is at system call
31 * tracing about to attempt one, returns the system call number.
32 * If @task is not executing a system call, i.e. it's blocked
33 * inside the kernel for a fault or signal, returns -1.
34 *
35 * It's only valid to call this when @task is known to be blocked.
36 */
37long syscall_get_nr(struct task_struct *task, struct pt_regs *regs);
38
39/**
40 * syscall_rollback - roll back registers after an aborted system call
41 * @task: task of interest, must be in system call exit tracing
42 * @regs: task_pt_regs() of @task
43 *
44 * It's only valid to call this when @task is stopped for system
45 * call exit tracing (due to TIF_SYSCALL_TRACE or TIF_SYSCALL_AUDIT),
46 * after tracehook_report_syscall_entry() returned nonzero to prevent
47 * the system call from taking place.
48 *
49 * This rolls back the register state in @regs so it's as if the
50 * system call instruction was a no-op. The registers containing
51 * the system call number and arguments are as they were before the
52 * system call instruction. This may not be the same as what the
53 * register state looked like at system call entry tracing.
54 */
55void syscall_rollback(struct task_struct *task, struct pt_regs *regs);
56
57/**
58 * syscall_get_error - check result of traced system call
59 * @task: task of interest, must be blocked
60 * @regs: task_pt_regs() of @task
61 *
62 * Returns 0 if the system call succeeded, or -ERRORCODE if it failed.
63 *
64 * It's only valid to call this when @task is stopped for tracing on exit
65 * from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
66 */
67long syscall_get_error(struct task_struct *task, struct pt_regs *regs);
68
69/**
70 * syscall_get_return_value - get the return value of a traced system call
71 * @task: task of interest, must be blocked
72 * @regs: task_pt_regs() of @task
73 *
74 * Returns the return value of the successful system call.
75 * This value is meaningless if syscall_get_error() returned nonzero.
76 *
77 * It's only valid to call this when @task is stopped for tracing on exit
78 * from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
79 */
80long syscall_get_return_value(struct task_struct *task, struct pt_regs *regs);
81
82/**
83 * syscall_set_return_value - change the return value of a traced system call
84 * @task: task of interest, must be blocked
85 * @regs: task_pt_regs() of @task
86 * @error: negative error code, or zero to indicate success
87 * @val: user return value if @error is zero
88 *
89 * This changes the results of the system call that user mode will see.
90 * If @error is zero, the user sees a successful system call with a
91 * return value of @val. If @error is nonzero, it's a negated errno
92 * code; the user sees a failed system call with this errno code.
93 *
94 * It's only valid to call this when @task is stopped for tracing on exit
95 * from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
96 */
97void syscall_set_return_value(struct task_struct *task, struct pt_regs *regs,
98 int error, long val);
99
100/**
101 * syscall_get_arguments - extract system call parameter values
102 * @task: task of interest, must be blocked
103 * @regs: task_pt_regs() of @task
104 * @i: argument index [0,5]
105 * @n: number of arguments; n+i must be [1,6].
106 * @args: array filled with argument values
107 *
108 * Fetches @n arguments to the system call starting with the @i'th argument
109 * (from 0 through 5). Argument @i is stored in @args[0], and so on.
110 * An arch inline version is probably optimal when @i and @n are constants.
111 *
112 * It's only valid to call this when @task is stopped for tracing on
113 * entry to a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
114 * It's invalid to call this with @i + @n > 6; we only support system calls
115 * taking up to 6 arguments.
116 */
117void syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
118 unsigned int i, unsigned int n, unsigned long *args);
119
120/**
121 * syscall_set_arguments - change system call parameter value
122 * @task: task of interest, must be in system call entry tracing
123 * @regs: task_pt_regs() of @task
124 * @i: argument index [0,5]
125 * @n: number of arguments; n+i must be [1,6].
126 * @args: array of argument values to store
127 *
128 * Changes @n arguments to the system call starting with the @i'th argument.
129 * @n'th argument to @val. Argument @i gets value @args[0], and so on.
130 * An arch inline version is probably optimal when @i and @n are constants.
131 *
132 * It's only valid to call this when @task is stopped for tracing on
133 * entry to a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
134 * It's invalid to call this with @i + @n > 6; we only support system calls
135 * taking up to 6 arguments.
136 */
137void syscall_set_arguments(struct task_struct *task, struct pt_regs *regs,
138 unsigned int i, unsigned int n,
139 const unsigned long *args);
140
141#endif /* _ASM_SYSCALL_H */
diff --git a/include/linux/tracehook.h b/include/linux/tracehook.h
index 32867ab86c70..589f429619c9 100644
--- a/include/linux/tracehook.h
+++ b/include/linux/tracehook.h
@@ -103,7 +103,8 @@ static inline void ptrace_report_syscall(struct pt_regs *regs)
103 * the system call. That must prevent normal entry so no system call is 103 * the system call. That must prevent normal entry so no system call is
104 * made. If @task ever returns to user mode after this, its register state 104 * made. If @task ever returns to user mode after this, its register state
105 * is unspecified, but should be something harmless like an %ENOSYS error 105 * is unspecified, but should be something harmless like an %ENOSYS error
106 * return. 106 * return. It should preserve enough information so that syscall_rollback()
107 * can work (see asm-generic/syscall.h).
107 * 108 *
108 * Called without locks, just after entering kernel mode. 109 * Called without locks, just after entering kernel mode.
109 */ 110 */