[pushed] Warn if /proc is not accessible (was: Re: [PATCH] Check if /proc is usable on gdbserver start)
Commit Message
On 07/04/2018 12:19 PM, Vyacheslav Barinov wrote:
>
> Okay, if the gdbserver can work without /proc, then just warning for cases
> like this is enough.
Alright, here's what I've merged.
I added a new linux_ptrace_init_warnings routine to nat/linux-procfs.c
very similar in spirit to the existing linux_ptrace_init_warnings
and called it from the same places. This makes native debugging
with GDB warn too.
From 7c65a87e84f79155a9e9f59890340f85387df8a1 Mon Sep 17 00:00:00 2001
From: Vyacheslav Barinov <v.barinov@samsung.com>
Date: Wed, 4 Jul 2018 16:13:29 +0100
Subject: [PATCH] Warn if /proc is not accessible
There's a buildroot where I want to debug a binary, and I tried to
connect to it from outside, but got very weird errors like
architecture mismatch or protocol errors. At last, after switching on
'--debug' for gdbserver I found a message 'Can't open /proc/pid/'
message and suddenly found that I forgot to mount procfs in my
buildroot.
Make discovering the problem easier by making GDB / GDBserver warn
(even without --debug) if /proc can not be accessed.
Native debugging:
(gdb) start
Temporary breakpoint 1 at 0x400835: file test.c, line 10.
Starting program: /tmp/test
warning: /proc is not accessible.
GDBserver/remote debugging:
$ ./gdbserver :9999 ./gdbserver
gdbserver: /proc is not accessible.
gdb/ChangeLog:
2018-07-04 Vyacheslav Barinov <v.barinov@samsung.com>
Pedro Alves <palves@redhat.com>
* linux-nat.c (linux_init_ptrace): Rename to ...
(linux_init_ptrace_procfs): ... this. Call
linux_proc_init_warnings.
(linux_nat_target::post_attach)
(linux_nat_target::post_startup_inferior): Adjust.
* nat/linux-procfs.c (linux_proc_init_warnings): Define function.
* nat/linux-procfs.h (linux_proc_init_warnings): Declare function.
gdb/gdbserver/ChangeLog:
2018-07-04 Vyacheslav Barinov <v.barinov@samsung.com>
Pedro Alves <palves@redhat.com>
* linux-low.c (initialize_low): Call linux_proc_init_warnings.
---
gdb/gdbserver/linux-low.c | 1 +
gdb/linux-nat.c | 11 ++++++-----
gdb/nat/linux-procfs.c | 17 +++++++++++++++++
gdb/nat/linux-procfs.h | 5 +++++
4 files changed, 29 insertions(+), 5 deletions(-)
@@ -7558,6 +7558,7 @@ initialize_low (void)
set_target_ops (&linux_target_ops);
linux_ptrace_init_warnings ();
+ linux_proc_init_warnings ();
sigchld_action.sa_handler = sigchld_handler;
sigemptyset (&sigchld_action.sa_mask);
@@ -384,18 +384,19 @@ linux_nat_ptrace_options (int attached)
return options;
}
-/* Initialize ptrace warnings and check for supported ptrace
- features given PID.
+/* Initialize ptrace and procfs warnings and check for supported
+ ptrace features given PID.
ATTACHED should be nonzero iff we attached to the inferior. */
static void
-linux_init_ptrace (pid_t pid, int attached)
+linux_init_ptrace_procfs (pid_t pid, int attached)
{
int options = linux_nat_ptrace_options (attached);
linux_enable_event_reporting (pid, options);
linux_ptrace_init_warnings ();
+ linux_proc_init_warnings ();
}
linux_nat_target::~linux_nat_target ()
@@ -404,13 +405,13 @@ linux_nat_target::~linux_nat_target ()
void
linux_nat_target::post_attach (int pid)
{
- linux_init_ptrace (pid, 1);
+ linux_init_ptrace_procfs (pid, 1);
}
void
linux_nat_target::post_startup_inferior (ptid_t ptid)
{
- linux_init_ptrace (ptid.pid (), 0);
+ linux_init_ptrace_procfs (ptid.pid (), 0);
}
/* Return the number of known LWPs in the tgid given by PID. */
@@ -357,3 +357,20 @@ linux_proc_pid_to_exec_file (int pid)
return buf;
}
+
+/* See linux-procfs.h. */
+
+void
+linux_proc_init_warnings ()
+{
+ static bool warned = false;
+
+ if (warned)
+ return;
+ warned = true;
+
+ struct stat st;
+
+ if (stat ("/proc/self", &st) != 0)
+ warning (_("/proc is not accessible."));
+}
@@ -80,4 +80,9 @@ extern int linux_proc_task_list_dir_exists (pid_t pid);
extern char *linux_proc_pid_to_exec_file (int pid);
+/* Display possible problems on this system. Display them only once
+ per GDB execution. */
+
+extern void linux_proc_init_warnings ();
+
#endif /* COMMON_LINUX_PROCFS_H */