static void
i386_linux_resume (ptid_t ptid, int step, enum target_signal signal)
{
int pid = PIDGET (ptid);
int request = PTRACE_CONT;
if (pid == -1)
/* Resume all threads. */
/* I think this only gets used in the non-threaded case, where "resume
all threads" and "resume inferior_ptid" are the same. */
pid = PIDGET (inferior_ptid);
if (step)
{
CORE_ADDR pc = read_pc_pid (pid_to_ptid (pid));
gdb_byte buf[LINUX_SYSCALL_LEN];
request = PTRACE_SINGLESTEP;
/* Returning from a signal trampoline is done by calling a
special system call (sigreturn or rt_sigreturn, see
i386-linux-tdep.c for more information). This system call
restores the registers that were saved when the signal was
raised, including %eflags. That means that single-stepping
won't work. Instead, we'll have to modify the signal context
that's about to be restored, and set the trace flag there. */
/* First check if PC is at a system call. */
if (deprecated_read_memory_nobpt (pc, buf, LINUX_SYSCALL_LEN) == 0
&& memcmp (buf, linux_syscall, LINUX_SYSCALL_LEN) == 0)
{
int syscall = read_register_pid (LINUX_SYSCALL_REGNUM,
pid_to_ptid (pid));
/* Then check the system call number. */
if (syscall == SYS_sigreturn || syscall == SYS_rt_sigreturn)
{
CORE_ADDR sp = read_register (I386_ESP_REGNUM);
CORE_ADDR addr = sp;
unsigned long int eflags;
if (syscall == SYS_rt_sigreturn)
addr = read_memory_integer (sp + 8, 4) + 20;
/* Set the trace flag in the context that's about to be
restored. */
addr += LINUX_SIGCONTEXT_EFLAGS_OFFSET;
read_memory (addr, (gdb_byte *) &eflags, 4);
eflags |= 0x0100;
write_memory (addr, (gdb_byte *) &eflags, 4);
}
}
}
if (ptrace (request, pid, 0, target_signal_to_host (signal)) == -1)
perror_with_name (("ptrace"));
}
static CORE_ADDR
mn10300_read_pc (ptid_t ptid)
{
return read_register_pid (E_PC_REGNUM, ptid);
}
