ebiederm@xxxxxxxxxxxx (Eric W. Biederman) writes: > Oleg Nesterov recently asked[1] why is there an unshare_files in > do_coredump. After digging through all of the callers of lookup_fd it > turns out that it is > arch/powerpc/platforms/cell/spufs/coredump.c:coredump_next_context > that needs the unshare_files in do_coredump. > > Looking at the history[2] this code was also the only piece of coredump code > that required the unshare_files when the unshare_files was added. > > Looking at that code it turns out that cell is also the only > architecture that implements elf_coredump_extra_notes_size and > elf_coredump_extra_notes_write. > > I looked at the gdb repo[3] support for cell has been removed[4] in binutils > 2.34. Geoff Levand reports he is still getting questions on how to > run modern kernels on the PS3, from people using 3rd party firmware so > this code is not dead. According to Wikipedia the last PS3 shipped in > Japan sometime in 2017. So it will probably be a little while before > everyone's hardware dies. > > Add some comments briefly documenting the coredump code that exists > only to support cell spufs to make it easier to understand the > coredump code. Eventually the hardware will be dead, or their won't > be userspace tools, or the coredump code will be refactored and it > will be too difficult to update a dead architecture and these comments > make it easy to tell where to pull to remove cell spufs support. > > [1] https://lkml.kernel.org/r/20201123175052.GA20279@xxxxxxxxxx > [2] 179e037fc137 ("do_coredump(): make sure that descriptor table isn't shared") > [3] git://sourceware.org/git/binutils-gdb.git > [4] abf516c6931a ("Remove Cell Broadband Engine debugging support"). > Signed-off-by: Eric W. Biederman <ebiederm@xxxxxxxxxxxx> > --- > > Does this change look good to people? I think it captures this state of > things and makes things clearer without breaking anything or removing > functionality for anyone. I haven't heard anything except a general ack to the concept of comments. So I am applying this. Eric > > fs/binfmt_elf.c | 2 ++ > fs/coredump.c | 1 + > 2 files changed, 3 insertions(+) > > diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c > index b6b3d052ca86..c1996f0aeaed 100644 > --- a/fs/binfmt_elf.c > +++ b/fs/binfmt_elf.c > @@ -2198,6 +2198,7 @@ static int elf_core_dump(struct coredump_params *cprm) > { > size_t sz = get_note_info_size(&info); > > + /* For cell spufs */ > sz += elf_coredump_extra_notes_size(); > > phdr4note = kmalloc(sizeof(*phdr4note), GFP_KERNEL); > @@ -2261,6 +2262,7 @@ static int elf_core_dump(struct coredump_params *cprm) > if (!write_note_info(&info, cprm)) > goto end_coredump; > > + /* For cell spufs */ > if (elf_coredump_extra_notes_write(cprm)) > goto end_coredump; > > diff --git a/fs/coredump.c b/fs/coredump.c > index abf807235262..3ff17eea812e 100644 > --- a/fs/coredump.c > +++ b/fs/coredump.c > @@ -790,6 +790,7 @@ void do_coredump(const kernel_siginfo_t *siginfo) > } > > /* get us an unshared descriptor table; almost always a no-op */ > + /* The cell spufs coredump code reads the file descriptor tables */ > retval = unshare_files(); > if (retval) > goto close_fail;
