trace.c revision 97f13e3fca546aa292ba5d8aa6011338e64f2f7a 
1#include "config.h"
2
3#include <string.h>
4#include <sys/types.h>
5#include <sys/wait.h>
6#include <signal.h>
7#include <sys/ptrace.h>
8#include <asm/ptrace.h>
9
10#include "proc.h"
11#include "common.h"
12#include "output.h"
13#include "ptrace.h"
14
15#if (!defined(PTRACE_PEEKUSER) && defined(PTRACE_PEEKUSR))
16# define PTRACE_PEEKUSER PTRACE_PEEKUSR
17#endif
18
19#if (!defined(PTRACE_POKEUSER) && defined(PTRACE_POKEUSR))
20# define PTRACE_POKEUSER PTRACE_POKEUSR
21#endif
22
23#define off_r0 ((void *)0)
24#define off_r7 ((void *)28)
25#define off_ip ((void *)48)
26#define off_pc ((void *)60)
27
28void
29get_arch_dep(Process *proc) {
30	proc_archdep *a;
31
32	if (!proc->arch_ptr)
33		proc->arch_ptr = (void *)malloc(sizeof(proc_archdep));
34	a = (proc_archdep *) (proc->arch_ptr);
35	a->valid = (ptrace(PTRACE_GETREGS, proc->pid, 0, &a->regs) >= 0);
36}
37
38/* Returns 0 if not a syscall,
39 *         1 if syscall entry, 2 if syscall exit,
40 *         3 if arch-specific syscall entry, 4 if arch-specific syscall exit,
41 *         -1 on error.
42 */
43int
44syscall_p(Process *proc, int status, int *sysnum) {
45	if (WIFSTOPPED(status)
46	    && WSTOPSIG(status) == (SIGTRAP | proc->tracesysgood)) {
47		/* get the user's pc (plus 8) */
48		unsigned pc = ptrace(PTRACE_PEEKUSER, proc->pid, off_pc, 0);
49		pc = pc - 4;
50		/* fetch the SWI instruction */
51		unsigned insn = ptrace(PTRACE_PEEKTEXT, proc->pid,
52				       (void *)pc, 0);
53		int ip = ptrace(PTRACE_PEEKUSER, proc->pid, off_ip, 0);
54
55		if (insn == 0xef000000 || insn == 0x0f000000
56		    || (insn & 0xffff0000) == 0xdf000000) {
57			/* EABI syscall */
58			*sysnum = ptrace(PTRACE_PEEKUSER, proc->pid, off_r7, 0);
59		} else if ((insn & 0xfff00000) == 0xef900000) {
60			/* old ABI syscall */
61			*sysnum = insn & 0xfffff;
62		} else {
63			/* TODO: handle swi<cond> variations */
64			/* one possible reason for getting in here is that we
65			 * are coming from a signal handler, so the current
66			 * PC does not point to the instruction just after the
67			 * "swi" one. */
68			output_line(proc, "unexpected instruction 0x%x at %p",
69				    insn, pc);
70			return 0;
71		}
72		if ((*sysnum & 0xf0000) == 0xf0000) {
73			/* arch-specific syscall */
74			*sysnum &= ~0xf0000;
75			return ip ? 4 : 3;
76		}
77		/* ARM syscall convention: on syscall entry, ip is zero;
78		 * on syscall exit, ip is non-zero */
79		return ip ? 2 : 1;
80	}
81	return 0;
82}
83
84long
85gimme_arg(enum tof type, Process *proc, int arg_num, struct arg_type_info *info)
86{
87	proc_archdep *a = (proc_archdep *) proc->arch_ptr;
88
89	if (arg_num == -1) {	/* return value */
90		return ptrace(PTRACE_PEEKUSER, proc->pid, off_r0, 0);
91	}
92
93	/* deal with the ARM calling conventions */
94	if (type == LT_TOF_FUNCTION || type == LT_TOF_FUNCTIONR) {
95		if (arg_num < 4) {
96			if (a->valid && type == LT_TOF_FUNCTION)
97				return a->regs.uregs[arg_num];
98			if (a->valid && type == LT_TOF_FUNCTIONR)
99				return a->func_arg[arg_num];
100			return ptrace(PTRACE_PEEKUSER, proc->pid,
101				      (void *)(4 * arg_num), 0);
102		} else {
103			return ptrace(PTRACE_PEEKDATA, proc->pid,
104				      proc->stack_pointer + 4 * (arg_num - 4),
105				      0);
106		}
107	} else if (type == LT_TOF_SYSCALL || type == LT_TOF_SYSCALLR) {
108		if (arg_num < 5) {
109			if (a->valid && type == LT_TOF_SYSCALL)
110				return a->regs.uregs[arg_num];
111			if (a->valid && type == LT_TOF_SYSCALLR)
112				return a->sysc_arg[arg_num];
113			return ptrace(PTRACE_PEEKUSER, proc->pid,
114				      (void *)(4 * arg_num), 0);
115		} else {
116			return ptrace(PTRACE_PEEKDATA, proc->pid,
117				      proc->stack_pointer + 4 * (arg_num - 5),
118				      0);
119		}
120	} else {
121		fprintf(stderr, "gimme_arg called with wrong arguments\n");
122		exit(1);
123	}
124
125	return 0;
126}
127