/* GNU/Linux native-dependent code common to multiple platforms.
- Copyright (C) 2001-2022 Free Software Foundation, Inc.
+ Copyright (C) 2001-2023 Free Software Foundation, Inc.
This file is part of GDB.
#include "symfile.h"
#include "gdbsupport/agent.h"
#include "tracepoint.h"
-#include "gdbsupport/buffer.h"
#include "target-descriptions.h"
#include "gdbsupport/filestuff.h"
#include "objfiles.h"
static void save_stop_reason (struct lwp_info *lp);
+static bool proc_mem_file_is_writable ();
static void close_proc_mem_file (pid_t pid);
static void open_proc_mem_file (ptid_t ptid);
linux_enable_event_reporting (pid, options);
linux_ptrace_init_warnings ();
linux_proc_init_warnings ();
+ proc_mem_file_is_writable ();
}
linux_nat_target::~linux_nat_target ()
gdb_signal_to_string (signo));
}
- internal_error (__FILE__, __LINE__,
- _("unexpected status %d for PID %ld"),
+ internal_error (_("unexpected status %d for PID %ld"),
status, (long) ptid.lwp ());
}
if (tp->has_pending_waitstatus ())
{
/* If the thread has a pending event, and it was stopped with a
- signal, use that signal to resume it. If it has a pending
+ signal, use that signal to resume it. If it has a pending
event of another kind, it was not stopped with a signal, so
resume it without a signal. */
if (tp->pending_waitstatus ().kind () == TARGET_WAITKIND_STOPPED)
}
void
-linux_nat_target::resume (ptid_t ptid, int step, enum gdb_signal signo)
+linux_nat_target::resume (ptid_t scope_ptid, int step, enum gdb_signal signo)
{
struct lwp_info *lp;
- int resume_many;
linux_nat_debug_printf ("Preparing to %s %s, %s, inferior_ptid %s",
step ? "step" : "resume",
- ptid.to_string ().c_str (),
+ scope_ptid.to_string ().c_str (),
(signo != GDB_SIGNAL_0
? strsignal (gdb_signal_to_host (signo)) : "0"),
inferior_ptid.to_string ().c_str ());
- /* A specific PTID means `step only this process id'. */
- resume_many = (minus_one_ptid == ptid
- || ptid.is_pid ());
-
/* Mark the lwps we're resuming as resumed and update their
last_resume_kind to resume_continue. */
- iterate_over_lwps (ptid, resume_set_callback);
+ iterate_over_lwps (scope_ptid, resume_set_callback);
- /* See if it's the current inferior that should be handled
- specially. */
- if (resume_many)
- lp = find_lwp_pid (inferior_ptid);
- else
- lp = find_lwp_pid (ptid);
+ lp = find_lwp_pid (inferior_ptid);
gdb_assert (lp != NULL);
/* Remember if we're stepping. */
if (target_can_async_p ())
{
- target_async (1);
+ target_async (true);
/* Tell the event loop we have something to process. */
async_file_mark ();
}
return;
}
- if (resume_many)
- iterate_over_lwps (ptid, [=] (struct lwp_info *info)
- {
- return linux_nat_resume_callback (info, lp);
- });
+ /* No use iterating unless we're resuming other threads. */
+ if (scope_ptid != lp->ptid)
+ iterate_over_lwps (scope_ptid, [=] (struct lwp_info *info)
+ {
+ return linux_nat_resume_callback (info, lp);
+ });
linux_nat_debug_printf ("%s %s, %s (resume event thread)",
step ? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
if (ret == -1)
perror_with_name (_("waiting for new child"));
else if (ret != new_pid)
- internal_error (__FILE__, __LINE__,
- _("wait returned unexpected PID %d"), ret);
+ internal_error (_("wait returned unexpected PID %d"), ret);
else if (!WIFSTOPPED (status))
- internal_error (__FILE__, __LINE__,
- _("wait returned unexpected status 0x%x"), status);
+ internal_error (_("wait returned unexpected status 0x%x"), status);
}
ptid_t child_ptid (new_pid, new_pid);
{
/* The process is not using thread_db. Add the LWP to
GDB's list. */
- target_post_attach (new_lp->ptid.lwp ());
add_thread (linux_target, new_lp->ptid);
}
return 0;
}
- internal_error (__FILE__, __LINE__,
- _("unknown ptrace event %d"), event);
+ internal_error (_("unknown ptrace event %d"), event);
}
/* Suspend waiting for a signal. We're mostly interested in
if (!linux_target->low_status_is_event (lp->status))
return;
+ inferior *inf = find_inferior_ptid (linux_target, lp->ptid);
+ if (inf->starting_up)
+ return;
+
regcache = get_thread_regcache (linux_target, lp->ptid);
gdbarch = regcache->arch ();
}
static enum target_xfer_status
-linux_xfer_siginfo (enum target_object object,
+linux_xfer_siginfo (ptid_t ptid, enum target_object object,
const char *annex, gdb_byte *readbuf,
const gdb_byte *writebuf, ULONGEST offset, ULONGEST len,
ULONGEST *xfered_len)
{
- int pid;
siginfo_t siginfo;
gdb_byte inf_siginfo[sizeof (siginfo_t)];
gdb_assert (object == TARGET_OBJECT_SIGNAL_INFO);
gdb_assert (readbuf || writebuf);
- pid = inferior_ptid.lwp ();
- if (pid == 0)
- pid = inferior_ptid.pid ();
-
if (offset > sizeof (siginfo))
return TARGET_XFER_E_IO;
- errno = 0;
- ptrace (PTRACE_GETSIGINFO, pid, (PTRACE_TYPE_ARG3) 0, &siginfo);
- if (errno != 0)
+ if (!linux_nat_get_siginfo (ptid, &siginfo))
return TARGET_XFER_E_IO;
/* When GDB is built as a 64-bit application, ptrace writes into
/* Convert back to ptrace layout before flushing it out. */
siginfo_fixup (&siginfo, inf_siginfo, 1);
+ int pid = get_ptrace_pid (ptid);
errno = 0;
ptrace (PTRACE_SETSIGINFO, pid, (PTRACE_TYPE_ARG3) 0, &siginfo);
if (errno != 0)
ULONGEST *xfered_len);
static enum target_xfer_status
-linux_proc_xfer_memory_partial (gdb_byte *readbuf, const gdb_byte *writebuf,
- ULONGEST offset, LONGEST len, ULONGEST *xfered_len);
+linux_proc_xfer_memory_partial (int pid, gdb_byte *readbuf,
+ const gdb_byte *writebuf, ULONGEST offset,
+ LONGEST len, ULONGEST *xfered_len);
enum target_xfer_status
linux_nat_target::xfer_partial (enum target_object object,
ULONGEST offset, ULONGEST len, ULONGEST *xfered_len)
{
if (object == TARGET_OBJECT_SIGNAL_INFO)
- return linux_xfer_siginfo (object, annex, readbuf, writebuf,
+ return linux_xfer_siginfo (inferior_ptid, object, annex, readbuf, writebuf,
offset, len, xfered_len);
/* The target is connected but no live inferior is selected. Pass
if (addr_bit < (sizeof (ULONGEST) * HOST_CHAR_BIT))
offset &= ((ULONGEST) 1 << addr_bit) - 1;
- return linux_proc_xfer_memory_partial (readbuf, writebuf,
- offset, len, xfered_len);
+ /* If /proc/pid/mem is writable, don't fallback to ptrace. If
+ the write via /proc/pid/mem fails because the inferior execed
+ (and we haven't seen the exec event yet), a subsequent ptrace
+ poke would incorrectly write memory to the post-exec address
+ space, while the core was trying to write to the pre-exec
+ address space. */
+ if (proc_mem_file_is_writable ())
+ return linux_proc_xfer_memory_partial (inferior_ptid.pid (), readbuf,
+ writebuf, offset, len,
+ xfered_len);
}
return inf_ptrace_target::xfer_partial (object, annex, readbuf, writebuf,
/* Accepts an integer PID; Returns a string representing a file that
can be opened to get the symbols for the child process. */
-char *
+const char *
linux_nat_target::pid_to_exec_file (int pid)
{
return linux_proc_pid_to_exec_file (pid);
fd, ptid.pid (), ptid.lwp ());
}
-/* Implement the to_xfer_partial target method using /proc/PID/mem.
- Because we can use a single read/write call, this can be much more
- efficient than banging away at PTRACE_PEEKTEXT. Also, unlike
- PTRACE_PEEKTEXT/PTRACE_POKETEXT, this works with running
- threads. */
+/* Helper for linux_proc_xfer_memory_partial and
+ proc_mem_file_is_writable. FD is the already opened /proc/pid/mem
+ file, and PID is the pid of the corresponding process. The rest of
+ the arguments are like linux_proc_xfer_memory_partial's. */
static enum target_xfer_status
-linux_proc_xfer_memory_partial (gdb_byte *readbuf, const gdb_byte *writebuf,
- ULONGEST offset, LONGEST len,
- ULONGEST *xfered_len)
+linux_proc_xfer_memory_partial_fd (int fd, int pid,
+ gdb_byte *readbuf, const gdb_byte *writebuf,
+ ULONGEST offset, LONGEST len,
+ ULONGEST *xfered_len)
{
ssize_t ret;
- auto iter = proc_mem_file_map.find (inferior_ptid.pid ());
- if (iter == proc_mem_file_map.end ())
- return TARGET_XFER_EOF;
-
- int fd = iter->second.fd ();
-
gdb_assert (fd != -1);
/* Use pread64/pwrite64 if available, since they save a syscall and can
if (ret == -1)
{
linux_nat_debug_printf ("accessing fd %d for pid %d failed: %s (%d)",
- fd, inferior_ptid.pid (),
- safe_strerror (errno), errno);
- return TARGET_XFER_EOF;
+ fd, pid, safe_strerror (errno), errno);
+ return TARGET_XFER_E_IO;
}
else if (ret == 0)
{
/* EOF means the address space is gone, the whole process exited
or execed. */
linux_nat_debug_printf ("accessing fd %d for pid %d got EOF",
- fd, inferior_ptid.pid ());
+ fd, pid);
return TARGET_XFER_EOF;
}
else
}
}
+/* Implement the to_xfer_partial target method using /proc/PID/mem.
+ Because we can use a single read/write call, this can be much more
+ efficient than banging away at PTRACE_PEEKTEXT. Also, unlike
+ PTRACE_PEEKTEXT/PTRACE_POKETEXT, this works with running
+ threads. */
+
+static enum target_xfer_status
+linux_proc_xfer_memory_partial (int pid, gdb_byte *readbuf,
+ const gdb_byte *writebuf, ULONGEST offset,
+ LONGEST len, ULONGEST *xfered_len)
+{
+ auto iter = proc_mem_file_map.find (pid);
+ if (iter == proc_mem_file_map.end ())
+ return TARGET_XFER_EOF;
+
+ int fd = iter->second.fd ();
+
+ return linux_proc_xfer_memory_partial_fd (fd, pid, readbuf, writebuf, offset,
+ len, xfered_len);
+}
+
+/* Check whether /proc/pid/mem is writable in the current kernel, and
+ return true if so. It wasn't writable before Linux 2.6.39, but
+ there's no way to know whether the feature was backported to older
+ kernels. So we check to see if it works. The result is cached,
+ and this is garanteed to be called once early during inferior
+ startup, so that any warning is printed out consistently between
+ GDB invocations. Note we don't call it during GDB startup instead
+ though, because then we might warn with e.g. just "gdb --version"
+ on sandboxed systems. See PR gdb/29907. */
+
+static bool
+proc_mem_file_is_writable ()
+{
+ static gdb::optional<bool> writable;
+
+ if (writable.has_value ())
+ return *writable;
+
+ writable.emplace (false);
+
+ /* We check whether /proc/pid/mem is writable by trying to write to
+ one of our variables via /proc/self/mem. */
+
+ int fd = gdb_open_cloexec ("/proc/self/mem", O_RDWR | O_LARGEFILE, 0).release ();
+
+ if (fd == -1)
+ {
+ warning (_("opening /proc/self/mem file failed: %s (%d)"),
+ safe_strerror (errno), errno);
+ return *writable;
+ }
+
+ SCOPE_EXIT { close (fd); };
+
+ /* This is the variable we try to write to. Note OFFSET below. */
+ volatile gdb_byte test_var = 0;
+
+ gdb_byte writebuf[] = {0x55};
+ ULONGEST offset = (uintptr_t) &test_var;
+ ULONGEST xfered_len;
+
+ enum target_xfer_status res
+ = linux_proc_xfer_memory_partial_fd (fd, getpid (), nullptr, writebuf,
+ offset, 1, &xfered_len);
+
+ if (res == TARGET_XFER_OK)
+ {
+ gdb_assert (xfered_len == 1);
+ gdb_assert (test_var == 0x55);
+ /* Success. */
+ *writable = true;
+ }
+
+ return *writable;
+}
+
/* Parse LINE as a signal set and add its set bits to SIGS. */
static void
/* Pause all */
target_stop (ptid);
- memcpy (s, "qTfSTM", sizeof ("qTfSTM"));
- s[sizeof ("qTfSTM")] = 0;
-
+ strcpy (s, "qTfSTM");
agent_run_command (pid, s, strlen (s) + 1);
/* Unpause all. */
}
while (*p++ == ','); /* comma-separated list */
- memcpy (s, "qTsSTM", sizeof ("qTsSTM"));
- s[sizeof ("qTsSTM")] = 0;
+ strcpy (s, "qTsSTM");
agent_run_command (pid, s, strlen (s) + 1);
p = s;
}
/* target_async implementation. */
void
-linux_nat_target::async (int enable)
+linux_nat_target::async (bool enable)
{
- if ((enable != 0) == is_async_p ())
+ if (enable == is_async_p ())
return;
/* Block child signals while we create/destroy the pipe, as their
if (enable)
{
if (!async_file_open ())
- internal_error (__FILE__, __LINE__, "creating event pipe failed.");
+ internal_error ("creating event pipe failed.");
add_file_handler (async_wait_fd (), handle_target_event, NULL,
"linux-nat");
int
linux_nat_target::fileio_open (struct inferior *inf, const char *filename,
int flags, int mode, int warn_if_slow,
- int *target_errno)
+ fileio_error *target_errno)
{
int nat_flags;
mode_t nat_mode;
gdb::optional<std::string>
linux_nat_target::fileio_readlink (struct inferior *inf, const char *filename,
- int *target_errno)
+ fileio_error *target_errno)
{
char buf[PATH_MAX];
int len;
int
linux_nat_target::fileio_unlink (struct inferior *inf, const char *filename,
- int *target_errno)
+ fileio_error *target_errno)
{
int ret;
/* See linux-nat.h. */
-int
+bool
linux_nat_get_siginfo (ptid_t ptid, siginfo_t *siginfo)
{
- int pid;
-
- pid = ptid.lwp ();
- if (pid == 0)
- pid = ptid.pid ();
-
- errno = 0;
- ptrace (PTRACE_GETSIGINFO, pid, (PTRACE_TYPE_ARG3) 0, siginfo);
- if (errno != 0)
- {
- memset (siginfo, 0, sizeof (*siginfo));
- return 0;
- }
- return 1;
+ int pid = get_ptrace_pid (ptid);
+ return ptrace (PTRACE_GETSIGINFO, pid, (PTRACE_TYPE_ARG3) 0, siginfo) == 0;
}
/* See nat/linux-nat.h. */
projects / binutils-gdb.git / blobdiff