[Bug gdb/28914] New: 'info proc mappings' does not display memory protections

[Bug gdb/28914] New: 'info proc mappings' does not display memory protections

[dominik.b.czarnota+bugzilla at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28914

            Bug ID: 28914
           Summary: 'info proc mappings' does not display memory
                    protections
           Product: gdb
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: gdb
          Assignee: unassigned at sourceware dot org
          Reporter: dominik.b.czarnota+bugzilla at gmail dot com
  Target Milestone: ---

Hello,

The `info proc mappings` command does not display the memory pages memory
protections which are present in the `/proc/$pid/maps` file fetched by GDB and
which is sometimes helpful to understand what the memory page refers to or why
a certain exception happened (e.g. segfault on memory access to a page with no
permissions).

Said all of this, I think that the `info proc mappings` command should simply
display an additional command with memory page protections if those are
available.

This would also simplify the implementation of commands like `vmmap` in plugins
that help with low-level debugging such as Pwndbg [0] or Gef [1] which
currently does parse /proc/$pid/maps by themselves (and have to do weird hacks
when doing this on remote targets like those run with qemu-user emulation).

Below we can see the output of `info proc mappings` and the corresponding
/proc/$pid/maps file:

```
(gdb) info proc mappings
process 21673
Mapped address spaces:

          Start Addr           End Addr       Size     Offset objfile
      0x555555554000     0x555555555000     0x1000        0x0 /home/dc/a.out
      0x555555754000     0x555555756000     0x2000        0x0 /home/dc/a.out
      0x7ffff7dd3000     0x7ffff7dfc000    0x29000        0x0
/lib/x86_64-linux-gnu/ld-2.27.so
      0x7ffff7ff7000     0x7ffff7ffa000     0x3000        0x0 [vvar]
      0x7ffff7ffa000     0x7ffff7ffc000     0x2000        0x0 [vdso]
      0x7ffff7ffc000     0x7ffff7ffe000     0x2000    0x29000
/lib/x86_64-linux-gnu/ld-2.27.so
      0x7ffff7ffe000     0x7ffff7fff000     0x1000        0x0
      0x7ffffffde000     0x7ffffffff000    0x21000        0x0 [stack]
  0xffffffffff600000 0xffffffffff601000     0x1000        0x0 [vsyscall]
```

Versus:

```
(gdb) !cat /proc/21673/maps
555555554000-555555555000 r-xp 00000000 fc:01 256615                    
/home/dc/a.out
555555754000-555555756000 rw-p 00000000 fc:01 256615                    
/home/dc/a.out
7ffff7dd3000-7ffff7dfc000 r-xp 00000000 fc:01 1444636                   
/lib/x86_64-linux-gnu/ld-2.27.so
7ffff7ff7000-7ffff7ffa000 r--p 00000000 00:00 0                          [vvar]
7ffff7ffa000-7ffff7ffc000 r-xp 00000000 00:00 0                          [vdso]
7ffff7ffc000-7ffff7ffe000 rw-p 00029000 fc:01 1444636                   
/lib/x86_64-linux-gnu/ld-2.27.so
7ffff7ffe000-7ffff7fff000 rw-p 00000000 00:00 0
7ffffffde000-7ffffffff000 rw-p 00000000 00:00 0                         
[stack]
ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0                 
[vsyscall]
(gdb)
```

[0] https://github.com/pwndbg/pwndbg/
[1] https://github.com/hugsy/gef

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug gdb/28914] 'info proc mappings' does not display memory protections

[dominik.b.czarnota+bugzilla at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28914

--- Comment #1 from Disconnect3d <dominik.b.czarnota+bugzilla at gmail dot com> ---
Created attachment 13991
  --> https://sourceware.org/bugzilla/attachment.cgi?id=13991&action=edit
Patch that implements the feature requested in this bug report

It seems that implementing this is straightforward and so please see the
attached patch.

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug gdb/28914] 'info proc mappings' does not display memory protections

[dominik.b.czarnota+bugzilla at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28914

Disconnect3d <dominik.b.czarnota+bugzilla at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Version|unknown                     |HEAD

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug gdb/28914] 'info proc mappings' does not display memory protections

[simark at simark dot ca]

https://sourceware.org/bugzilla/show_bug.cgi?id=28914

Simon Marchi <simark at simark dot ca> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |simark at simark dot ca
         Resolution|---                         |FIXED
             Status|UNCONFIRMED                 |RESOLVED

--- Comment #2 from Simon Marchi <simark at simark dot ca> ---
https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=29ef4c0699e1b46d41ade00ae07a54f979ea21cc

-- 
You are receiving this mail because:
You are on the CC list for the bug.