[PATCH] ldv/unwind: Improve stacktrace feature

[Luca Clementi]

On Thu, Oct 10, 2013 at 6:54 AM, Masatake YAMATO <yamato at redhat.com> wrote:
> Based on the discussion on strace-devel, I improved following points:
>
> * using unwind_ as prefix for functions exported from unwind.c
>
> * stacktrace for execve
>
>     About the most of system calls, stacktrace is captured and printed at
>     the same time, the system call exiting.  However, about execve, which
>     is marked with STACKTRACE_CAPTURE_IN_ENTERING(CE), stacktrace is
>     captured at the system call entering, and is printed at the exiting.
>     By capturing in the system call entering, user can know the process
>     context of execve is called.
>
>     struct queue_t and some manipulators are introduced for
>     capturing-at-entering and printing-at-exiting.
>
> * controlling the maps cache with STACKTRACE_MAKE_CACHE_INVALID(CI) marker
>
>     Currently stacktrace feature of strace needs the information of the
>     memory mapping. Some of system calls like mmap change the memory
>     mapping of the target process. Therefore unwind.c must track the
>     modification of memory mapping.
>
>     In older version the modification is tracked in print functions of
>     each system call. In this patch STACKTRACE_MAKE_CACHE_INVALID(CI)
>     marker is introduced. In stead of handling in print functions, the
>     modification is tracked in system call entering only if current
>     system call is marked with CI.
>
>     If new system call modifying the memory mapping is added, just
>     mark it with CI.
>
> * marking CI on brk, mremap, shmat, shmdt, and remap_file_pages.
>
> TODO:
>
> * Move the memory mapping cache to libuwind and use API for it.
>
>     See http://lists.nongnu.org/archive/html/libunwind-devel/2013-10/msg00001.html
>
> * Handle multi threads
>
>     If target threads are share the same address space, cache invalidation
>     on a thread must be propagated to the other threads.
>
> * Static link target
>
>   Target compiled with gcc -static, stacktrace is not
>   shown well through gdb can show it. Maybe libunwind
>   side issue.
>
> * Platform other than linux/x86_64
>
> * Test cases
>

Hey Masatake,
I think you email client messed up the patch.
I can't apply it is full of "=" at the end of lines.

I don't know what the maintainer prefers but shouldn't you push this
patch with all the required modification (for all the architectures)
and then ask to other plp to test them?


Luca