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-rw-r--r--lib/syscall.c57
1 files changed, 25 insertions, 32 deletions
diff --git a/lib/syscall.c b/lib/syscall.c
index 1a7077f20eae..fb328e7ccb08 100644
--- a/lib/syscall.c
+++ b/lib/syscall.c
@@ -5,16 +5,14 @@
5#include <linux/export.h> 5#include <linux/export.h>
6#include <asm/syscall.h> 6#include <asm/syscall.h>
7 7
8static int collect_syscall(struct task_struct *target, long *callno, 8static int collect_syscall(struct task_struct *target, struct syscall_info *info)
9 unsigned long args[6], unsigned int maxargs,
10 unsigned long *sp, unsigned long *pc)
11{ 9{
12 struct pt_regs *regs; 10 struct pt_regs *regs;
13 11
14 if (!try_get_task_stack(target)) { 12 if (!try_get_task_stack(target)) {
15 /* Task has no stack, so the task isn't in a syscall. */ 13 /* Task has no stack, so the task isn't in a syscall. */
16 *sp = *pc = 0; 14 memset(info, 0, sizeof(*info));
17 *callno = -1; 15 info->data.nr = -1;
18 return 0; 16 return 0;
19 } 17 }
20 18
@@ -24,12 +22,13 @@ static int collect_syscall(struct task_struct *target, long *callno,
24 return -EAGAIN; 22 return -EAGAIN;
25 } 23 }
26 24
27 *sp = user_stack_pointer(regs); 25 info->sp = user_stack_pointer(regs);
28 *pc = instruction_pointer(regs); 26 info->data.instruction_pointer = instruction_pointer(regs);
29 27
30 *callno = syscall_get_nr(target, regs); 28 info->data.nr = syscall_get_nr(target, regs);
31 if (*callno != -1L && maxargs > 0) 29 if (info->data.nr != -1L)
32 syscall_get_arguments(target, regs, 0, maxargs, args); 30 syscall_get_arguments(target, regs,
31 (unsigned long *)&info->data.args[0]);
33 32
34 put_task_stack(target); 33 put_task_stack(target);
35 return 0; 34 return 0;
@@ -38,41 +37,35 @@ static int collect_syscall(struct task_struct *target, long *callno,
38/** 37/**
39 * task_current_syscall - Discover what a blocked task is doing. 38 * task_current_syscall - Discover what a blocked task is doing.
40 * @target: thread to examine 39 * @target: thread to examine
41 * @callno: filled with system call number or -1 40 * @info: structure with the following fields:
42 * @args: filled with @maxargs system call arguments 41 * .sp - filled with user stack pointer
43 * @maxargs: number of elements in @args to fill 42 * .data.nr - filled with system call number or -1
44 * @sp: filled with user stack pointer 43 * .data.args - filled with @maxargs system call arguments
45 * @pc: filled with user PC 44 * .data.instruction_pointer - filled with user PC
46 * 45 *
47 * If @target is blocked in a system call, returns zero with *@callno 46 * If @target is blocked in a system call, returns zero with @info.data.nr
48 * set to the the call's number and @args filled in with its arguments. 47 * set to the the call's number and @info.data.args filled in with its
49 * Registers not used for system call arguments may not be available and 48 * arguments. Registers not used for system call arguments may not be available
50 * it is not kosher to use &struct user_regset calls while the system 49 * and it is not kosher to use &struct user_regset calls while the system
51 * call is still in progress. Note we may get this result if @target 50 * call is still in progress. Note we may get this result if @target
52 * has finished its system call but not yet returned to user mode, such 51 * has finished its system call but not yet returned to user mode, such
53 * as when it's stopped for signal handling or syscall exit tracing. 52 * as when it's stopped for signal handling or syscall exit tracing.
54 * 53 *
55 * If @target is blocked in the kernel during a fault or exception, 54 * If @target is blocked in the kernel during a fault or exception,
56 * returns zero with *@callno set to -1 and does not fill in @args. 55 * returns zero with *@info.data.nr set to -1 and does not fill in
57 * If so, it's now safe to examine @target using &struct user_regset 56 * @info.data.args. If so, it's now safe to examine @target using
58 * get() calls as long as we're sure @target won't return to user mode. 57 * &struct user_regset get() calls as long as we're sure @target won't return
58 * to user mode.
59 * 59 *
60 * Returns -%EAGAIN if @target does not remain blocked. 60 * Returns -%EAGAIN if @target does not remain blocked.
61 *
62 * Returns -%EINVAL if @maxargs is too large (maximum is six).
63 */ 61 */
64int task_current_syscall(struct task_struct *target, long *callno, 62int task_current_syscall(struct task_struct *target, struct syscall_info *info)
65 unsigned long args[6], unsigned int maxargs,
66 unsigned long *sp, unsigned long *pc)
67{ 63{
68 long state; 64 long state;
69 unsigned long ncsw; 65 unsigned long ncsw;
70 66
71 if (unlikely(maxargs > 6))
72 return -EINVAL;
73
74 if (target == current) 67 if (target == current)
75 return collect_syscall(target, callno, args, maxargs, sp, pc); 68 return collect_syscall(target, info);
76 69
77 state = target->state; 70 state = target->state;
78 if (unlikely(!state)) 71 if (unlikely(!state))
@@ -80,7 +73,7 @@ int task_current_syscall(struct task_struct *target, long *callno,
80 73
81 ncsw = wait_task_inactive(target, state); 74 ncsw = wait_task_inactive(target, state);
82 if (unlikely(!ncsw) || 75 if (unlikely(!ncsw) ||
83 unlikely(collect_syscall(target, callno, args, maxargs, sp, pc)) || 76 unlikely(collect_syscall(target, info)) ||
84 unlikely(wait_task_inactive(target, state) != ncsw)) 77 unlikely(wait_task_inactive(target, state) != ncsw))
85 return -EAGAIN; 78 return -EAGAIN;
86 79