From 1b919490e8ba30bf1d6941df0ed112b0e557017e Mon Sep 17 00:00:00 2001 From: Vyacheslav Barinov 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 Pedro Alves * 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 Pedro Alves * linux-low.c (initialize_low): Call linux_proc_init_warnings. --- gdb/ChangeLog | 11 +++++++++++ gdb/gdbserver/ChangeLog | 5 +++++ gdb/gdbserver/linux-low.c | 1 + gdb/linux-nat.c | 11 ++++++----- gdb/nat/linux-procfs.c | 17 +++++++++++++++++ gdb/nat/linux-procfs.h | 5 +++++ 6 files changed, 45 insertions(+), 5 deletions(-) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index ea1e7e371e9..0cece38e6b8 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,14 @@ +2018-07-04 Vyacheslav Barinov + Pedro Alves + + * 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. + 2018-07-04 Tom de Vries * dwarf2read.c (error_check_comp_unit_head): Move dwarf version diff --git a/gdb/gdbserver/ChangeLog b/gdb/gdbserver/ChangeLog index a59999a217a..ac644ceb7fb 100644 --- a/gdb/gdbserver/ChangeLog +++ b/gdb/gdbserver/ChangeLog @@ -1,3 +1,8 @@ +2018-07-04 Vyacheslav Barinov + Pedro Alves + + * linux-low.c (initialize_low): Call linux_proc_init_warnings. + 2018-07-03 Tom Tromey * linux-low.c: Update. diff --git a/gdb/gdbserver/linux-low.c b/gdb/gdbserver/linux-low.c index 6e026f1aab8..7c396ae3662 100644 --- a/gdb/gdbserver/linux-low.c +++ b/gdb/gdbserver/linux-low.c @@ -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); diff --git a/gdb/linux-nat.c b/gdb/linux-nat.c index 567cb064d3a..18d9a3872a5 100644 --- a/gdb/linux-nat.c +++ b/gdb/linux-nat.c @@ -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. */ diff --git a/gdb/nat/linux-procfs.c b/gdb/nat/linux-procfs.c index 1c236c543d9..6c15ea5cce3 100644 --- a/gdb/nat/linux-procfs.c +++ b/gdb/nat/linux-procfs.c @@ -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.")); +} diff --git a/gdb/nat/linux-procfs.h b/gdb/nat/linux-procfs.h index efb2911cb8f..2f8932e89c7 100644 --- a/gdb/nat/linux-procfs.h +++ b/gdb/nat/linux-procfs.h @@ -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 */ -- 2.30.2