trace.c revision 63184be8c577f5799e44db2a4e312a8240ad7751 
1#if HAVE_CONFIG_H
2#include "config.h"
3#endif
4
5#include <string.h>
6#include <sys/types.h>
7#include <sys/wait.h>
8#include <signal.h>
9#include <sys/ptrace.h>
10#include <asm/ptrace.h>
11
12#include "ltrace.h"
13#include "output.h"
14#include "ptrace.h"
15
16#if (!defined(PTRACE_PEEKUSER) && defined(PTRACE_PEEKUSR))
17# define PTRACE_PEEKUSER PTRACE_PEEKUSR
18#endif
19
20#if (!defined(PTRACE_POKEUSER) && defined(PTRACE_POKEUSR))
21# define PTRACE_POKEUSER PTRACE_POKEUSR
22#endif
23
24#define off_r0 0
25#define off_r7 28
26#define off_ip 48
27#define off_pc 60
28
29void get_arch_dep(struct process *proc)
30{
31	proc_archdep *a;
32
33	if (!proc->arch_ptr)
34		proc->arch_ptr = (void *)malloc(sizeof(proc_archdep));
35	a = (proc_archdep *) (proc->arch_ptr);
36	a->valid = (ptrace(PTRACE_GETREGS, proc->pid, 0, &a->regs) >= 0);
37}
38
39/* Returns 0 if not a syscall,
40 *         1 if syscall entry, 2 if syscall exit,
41 *         3 if arch-specific syscall entry, 4 if arch-specific syscall exit,
42 *         -1 on error.
43 */
44int syscall_p(struct process *proc, int status, int *sysnum)
45{
46	if (WIFSTOPPED(status)
47	    && WSTOPSIG(status) == (SIGTRAP | proc->tracesysgood)) {
48		/* get the user's pc (plus 8) */
49		int pc = ptrace(PTRACE_PEEKUSER, proc->pid, off_pc, 0);
50		/* fetch the SWI instruction */
51		int insn = ptrace(PTRACE_PEEKTEXT, proc->pid, pc - 4, 0);
52		int ip = ptrace(PTRACE_PEEKUSER, proc->pid, off_ip, 0);
53
54		if (insn == 0xef000000 || insn == 0x0f000000) {
55			/* EABI syscall */
56			*sysnum = ptrace(PTRACE_PEEKUSER, proc->pid, off_r7, 0);
57		} else if ((insn & 0xfff00000) == 0xef900000) {
58			/* old ABI syscall */
59			*sysnum = insn & 0xfffff;
60		} else {
61			/* TODO: handle swi<cond> variations */
62			/* one possible reason for getting in here is that we
63			 * are coming from a signal handler, so the current
64			 * PC does not point to the instruction just after the
65			 * "swi" one. */
66			output_line(proc, "unexpected instruction 0x%x at %p", insn, pc - 4);
67			return -1;
68		}
69		if ((*sysnum & 0xf0000) == 0xf0000) {
70			/* arch-specific syscall */
71			*sysnum &= ~0xf0000;
72			return ip ? 4 : 3;
73		}
74		/* ARM syscall convention: on syscall entry, ip is zero;
75		 * on syscall exit, ip is non-zero */
76		return ip ? 2 : 1;
77	}
78	return 0;
79}
80
81long gimme_arg(enum tof type, struct process *proc, int arg_num, arg_type_info *info)
82{
83	proc_archdep *a = (proc_archdep *) proc->arch_ptr;
84
85	if (arg_num == -1) {	/* return value */
86		return ptrace(PTRACE_PEEKUSER, proc->pid, off_r0, 0);
87	}
88
89	/* deal with the ARM calling conventions */
90	if (type == LT_TOF_FUNCTION || type == LT_TOF_FUNCTIONR) {
91		if (arg_num < 4) {
92			if (a->valid && type == LT_TOF_FUNCTION)
93				return a->regs.uregs[arg_num];
94			if (a->valid && type == LT_TOF_FUNCTIONR)
95				return a->func_arg[arg_num];
96			return ptrace(PTRACE_PEEKUSER, proc->pid, 4 * arg_num,
97				      0);
98		} else {
99			return ptrace(PTRACE_PEEKDATA, proc->pid,
100				      proc->stack_pointer + 4 * (arg_num - 4),
101				      0);
102		}
103	} else if (type == LT_TOF_SYSCALL || type == LT_TOF_SYSCALLR) {
104		if (arg_num < 5) {
105			if (a->valid && type == LT_TOF_SYSCALL)
106				return a->regs.uregs[arg_num];
107			if (a->valid && type == LT_TOF_SYSCALLR)
108				return a->sysc_arg[arg_num];
109			return ptrace(PTRACE_PEEKUSER, proc->pid, 4 * arg_num,
110				      0);
111		} else {
112			return ptrace(PTRACE_PEEKDATA, proc->pid,
113				      proc->stack_pointer + 4 * (arg_num - 5),
114				      0);
115		}
116	} else {
117		fprintf(stderr, "gimme_arg called with wrong arguments\n");
118		exit(1);
119	}
120
121	return 0;
122}
123
124void save_register_args(enum tof type, struct process *proc)
125{
126	proc_archdep *a = (proc_archdep *) proc->arch_ptr;
127	if (a->valid) {
128		if (type == LT_TOF_FUNCTION)
129			memcpy(a->func_arg, a->regs.uregs, sizeof(a->func_arg));
130		else
131			memcpy(a->sysc_arg, a->regs.uregs, sizeof(a->sysc_arg));
132	}
133}
134