<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/fs/binfmt_elf.c, branch v5.14</title>
<subtitle>Linux kernel source tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/'/>
<entry>
<title>Merge branch 'akpm' (patches from Andrew)</title>
<updated>2021-06-30T00:29:11+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2021-06-30T00:29:11+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=65090f30ab791810a3dc840317e57df05018559c'/>
<id>65090f30ab791810a3dc840317e57df05018559c</id>
<content type='text'>
Merge misc updates from Andrew Morton:
 "191 patches.

  Subsystems affected by this patch series: kthread, ia64, scripts,
  ntfs, squashfs, ocfs2, kernel/watchdog, and mm (gup, pagealloc, slab,
  slub, kmemleak, dax, debug, pagecache, gup, swap, memcg, pagemap,
  mprotect, bootmem, dma, tracing, vmalloc, kasan, initialization,
  pagealloc, and memory-failure)"

* emailed patches from Andrew Morton &lt;akpm@linux-foundation.org&gt;: (191 commits)
  mm,hwpoison: make get_hwpoison_page() call get_any_page()
  mm,hwpoison: send SIGBUS with error virutal address
  mm/page_alloc: split pcp-&gt;high across all online CPUs for cpuless nodes
  mm/page_alloc: allow high-order pages to be stored on the per-cpu lists
  mm: replace CONFIG_FLAT_NODE_MEM_MAP with CONFIG_FLATMEM
  mm: replace CONFIG_NEED_MULTIPLE_NODES with CONFIG_NUMA
  docs: remove description of DISCONTIGMEM
  arch, mm: remove stale mentions of DISCONIGMEM
  mm: remove CONFIG_DISCONTIGMEM
  m68k: remove support for DISCONTIGMEM
  arc: remove support for DISCONTIGMEM
  arc: update comment about HIGHMEM implementation
  alpha: remove DISCONTIGMEM and NUMA
  mm/page_alloc: move free_the_page
  mm/page_alloc: fix counting of managed_pages
  mm/page_alloc: improve memmap_pages dbg msg
  mm: drop SECTION_SHIFT in code comments
  mm/page_alloc: introduce vm.percpu_pagelist_high_fraction
  mm/page_alloc: limit the number of pages on PCP lists when reclaim is active
  mm/page_alloc: scale the number of pages that are batch freed
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Merge misc updates from Andrew Morton:
 "191 patches.

  Subsystems affected by this patch series: kthread, ia64, scripts,
  ntfs, squashfs, ocfs2, kernel/watchdog, and mm (gup, pagealloc, slab,
  slub, kmemleak, dax, debug, pagecache, gup, swap, memcg, pagemap,
  mprotect, bootmem, dma, tracing, vmalloc, kasan, initialization,
  pagealloc, and memory-failure)"

* emailed patches from Andrew Morton &lt;akpm@linux-foundation.org&gt;: (191 commits)
  mm,hwpoison: make get_hwpoison_page() call get_any_page()
  mm,hwpoison: send SIGBUS with error virutal address
  mm/page_alloc: split pcp-&gt;high across all online CPUs for cpuless nodes
  mm/page_alloc: allow high-order pages to be stored on the per-cpu lists
  mm: replace CONFIG_FLAT_NODE_MEM_MAP with CONFIG_FLATMEM
  mm: replace CONFIG_NEED_MULTIPLE_NODES with CONFIG_NUMA
  docs: remove description of DISCONTIGMEM
  arch, mm: remove stale mentions of DISCONIGMEM
  mm: remove CONFIG_DISCONTIGMEM
  m68k: remove support for DISCONTIGMEM
  arc: remove support for DISCONTIGMEM
  arc: update comment about HIGHMEM implementation
  alpha: remove DISCONTIGMEM and NUMA
  mm/page_alloc: move free_the_page
  mm/page_alloc: fix counting of managed_pages
  mm/page_alloc: improve memmap_pages dbg msg
  mm: drop SECTION_SHIFT in code comments
  mm/page_alloc: introduce vm.percpu_pagelist_high_fraction
  mm/page_alloc: limit the number of pages on PCP lists when reclaim is active
  mm/page_alloc: scale the number of pages that are batch freed
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>binfmt: remove in-tree usage of MAP_EXECUTABLE</title>
<updated>2021-06-29T17:53:50+00:00</updated>
<author>
<name>David Hildenbrand</name>
<email>david@redhat.com</email>
</author>
<published>2021-06-29T02:38:31+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=a4eec6a3dfb7a6257ddcacf15e9428fe5834ffd4'/>
<id>a4eec6a3dfb7a6257ddcacf15e9428fe5834ffd4</id>
<content type='text'>
Ever since commit e9714acf8c43 ("mm: kill vma flag VM_EXECUTABLE and
mm-&gt;num_exe_file_vmas"), VM_EXECUTABLE is gone and MAP_EXECUTABLE is
essentially completely ignored.  Let's remove all usage of MAP_EXECUTABLE.

[akpm@linux-foundation.org: fix blooper in fs/binfmt_aout.c. per David]

Link: https://lkml.kernel.org/r/20210421093453.6904-3-david@redhat.com
Signed-off-by: David Hildenbrand &lt;david@redhat.com&gt;
Acked-by: "Eric W. Biederman" &lt;ebiederm@xmission.com&gt;
Reviewed-by: Kees Cook &lt;keescook@chromium.org&gt;
Cc: Alexander Shishkin &lt;alexander.shishkin@linux.intel.com&gt;
Cc: Alexander Viro &lt;viro@zeniv.linux.org.uk&gt;
Cc: Arnaldo Carvalho de Melo &lt;acme@kernel.org&gt;
Cc: Borislav Petkov &lt;bp@alien8.de&gt;
Cc: Catalin Marinas &lt;catalin.marinas@arm.com&gt;
Cc: Don Zickus &lt;dzickus@redhat.com&gt;
Cc: Feng Tang &lt;feng.tang@intel.com&gt;
Cc: Greg Ungerer &lt;gerg@linux-m68k.org&gt;
Cc: "H. Peter Anvin" &lt;hpa@zytor.com&gt;
Cc: Ingo Molnar &lt;mingo@redhat.com&gt;
Cc: Jiri Olsa &lt;jolsa@redhat.com&gt;
Cc: Kevin Brodsky &lt;Kevin.Brodsky@arm.com&gt;
Cc: Mark Rutland &lt;mark.rutland@arm.com&gt;
Cc: Michal Hocko &lt;mhocko@suse.com&gt;
Cc: Mike Rapoport &lt;rppt@kernel.org&gt;
Cc: Namhyung Kim &lt;namhyung@kernel.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Ever since commit e9714acf8c43 ("mm: kill vma flag VM_EXECUTABLE and
mm-&gt;num_exe_file_vmas"), VM_EXECUTABLE is gone and MAP_EXECUTABLE is
essentially completely ignored.  Let's remove all usage of MAP_EXECUTABLE.

[akpm@linux-foundation.org: fix blooper in fs/binfmt_aout.c. per David]

Link: https://lkml.kernel.org/r/20210421093453.6904-3-david@redhat.com
Signed-off-by: David Hildenbrand &lt;david@redhat.com&gt;
Acked-by: "Eric W. Biederman" &lt;ebiederm@xmission.com&gt;
Reviewed-by: Kees Cook &lt;keescook@chromium.org&gt;
Cc: Alexander Shishkin &lt;alexander.shishkin@linux.intel.com&gt;
Cc: Alexander Viro &lt;viro@zeniv.linux.org.uk&gt;
Cc: Arnaldo Carvalho de Melo &lt;acme@kernel.org&gt;
Cc: Borislav Petkov &lt;bp@alien8.de&gt;
Cc: Catalin Marinas &lt;catalin.marinas@arm.com&gt;
Cc: Don Zickus &lt;dzickus@redhat.com&gt;
Cc: Feng Tang &lt;feng.tang@intel.com&gt;
Cc: Greg Ungerer &lt;gerg@linux-m68k.org&gt;
Cc: "H. Peter Anvin" &lt;hpa@zytor.com&gt;
Cc: Ingo Molnar &lt;mingo@redhat.com&gt;
Cc: Jiri Olsa &lt;jolsa@redhat.com&gt;
Cc: Kevin Brodsky &lt;Kevin.Brodsky@arm.com&gt;
Cc: Mark Rutland &lt;mark.rutland@arm.com&gt;
Cc: Michal Hocko &lt;mhocko@suse.com&gt;
Cc: Mike Rapoport &lt;rppt@kernel.org&gt;
Cc: Namhyung Kim &lt;namhyung@kernel.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>sched: Change task_struct::state</title>
<updated>2021-06-18T09:43:09+00:00</updated>
<author>
<name>Peter Zijlstra</name>
<email>peterz@infradead.org</email>
</author>
<published>2021-06-11T08:28:17+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=2f064a59a11ff9bc22e52e9678bc601404c7cb34'/>
<id>2f064a59a11ff9bc22e52e9678bc601404c7cb34</id>
<content type='text'>
Change the type and name of task_struct::state. Drop the volatile and
shrink it to an 'unsigned int'. Rename it in order to find all uses
such that we can use READ_ONCE/WRITE_ONCE as appropriate.

Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Reviewed-by: Daniel Bristot de Oliveira &lt;bristot@redhat.com&gt;
Acked-by: Will Deacon &lt;will@kernel.org&gt;
Acked-by: Daniel Thompson &lt;daniel.thompson@linaro.org&gt;
Link: https://lore.kernel.org/r/20210611082838.550736351@infradead.org
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Change the type and name of task_struct::state. Drop the volatile and
shrink it to an 'unsigned int'. Rename it in order to find all uses
such that we can use READ_ONCE/WRITE_ONCE as appropriate.

Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Reviewed-by: Daniel Bristot de Oliveira &lt;bristot@redhat.com&gt;
Acked-by: Will Deacon &lt;will@kernel.org&gt;
Acked-by: Daniel Thompson &lt;daniel.thompson@linaro.org&gt;
Link: https://lore.kernel.org/r/20210611082838.550736351@infradead.org
</pre>
</div>
</content>
</entry>
<entry>
<title>coredump: don't bother with do_truncate()</title>
<updated>2021-03-08T15:21:11+00:00</updated>
<author>
<name>Al Viro</name>
<email>viro@zeniv.linux.org.uk</email>
</author>
<published>2020-03-08T13:16:37+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=d0f1088b31db2d03497a74ca67755df5515f8ff4'/>
<id>d0f1088b31db2d03497a74ca67755df5515f8ff4</id>
<content type='text'>
have dump_skip() just remember how much needs to be skipped,
leave actual seeks/writing zeroes to the next dump_emit()
or the end of coredump output, whichever comes first.
And instead of playing with do_truncate() in the end, just
write one NUL at the end of the last gap (if any).

Signed-off-by: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
have dump_skip() just remember how much needs to be skipped,
leave actual seeks/writing zeroes to the next dump_emit()
or the end of coredump output, whichever comes first.
And instead of playing with do_truncate() in the end, just
write one NUL at the end of the last gap (if any).

Signed-off-by: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge branch 'parisc-5.12-1' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux</title>
<updated>2021-02-21T21:20:41+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2021-02-21T21:20:41+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=08179b47e1fdf288e5d59f90e5ce31513bb019c3'/>
<id>08179b47e1fdf288e5d59f90e5ce31513bb019c3</id>
<content type='text'>
Pull parisc updates from Helge Deller:

 - Optimize parisc page table locks by using the existing
   page_table_lock

 - Export argv0-preserve flag in binfmt_misc for usage in qemu-user

 - Fix interrupt table (IVT) checksum so firmware will call crash
   handler (HPMC)

 - Increase IRQ stack to 64kb on 64-bit kernel

 - Switch to common devmem_is_allowed() implementation

 - Minor fix to get_whan()

* 'parisc-5.12-1' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux:
  binfmt_misc: pass binfmt_misc flags to the interpreter
  parisc: Optimize per-pagetable spinlocks
  parisc: Replace test_ti_thread_flag() with test_tsk_thread_flag()
  parisc: Bump 64-bit IRQ stack size to 64 KB
  parisc: Fix IVT checksum calculation wrt HPMC
  parisc: Use the generic devmem_is_allowed()
  parisc: Drop out of get_whan() if task is running again
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull parisc updates from Helge Deller:

 - Optimize parisc page table locks by using the existing
   page_table_lock

 - Export argv0-preserve flag in binfmt_misc for usage in qemu-user

 - Fix interrupt table (IVT) checksum so firmware will call crash
   handler (HPMC)

 - Increase IRQ stack to 64kb on 64-bit kernel

 - Switch to common devmem_is_allowed() implementation

 - Minor fix to get_whan()

* 'parisc-5.12-1' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux:
  binfmt_misc: pass binfmt_misc flags to the interpreter
  parisc: Optimize per-pagetable spinlocks
  parisc: Replace test_ti_thread_flag() with test_tsk_thread_flag()
  parisc: Bump 64-bit IRQ stack size to 64 KB
  parisc: Fix IVT checksum calculation wrt HPMC
  parisc: Use the generic devmem_is_allowed()
  parisc: Drop out of get_whan() if task is running again
</pre>
</div>
</content>
</entry>
<entry>
<title>binfmt_misc: pass binfmt_misc flags to the interpreter</title>
<updated>2021-02-15T17:28:30+00:00</updated>
<author>
<name>Laurent Vivier</name>
<email>laurent@vivier.eu</email>
</author>
<published>2020-01-28T13:25:39+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=2347961b11d4079deace3c81dceed460c08a8fc1'/>
<id>2347961b11d4079deace3c81dceed460c08a8fc1</id>
<content type='text'>
It can be useful to the interpreter to know which flags are in use.

For instance, knowing if the preserve-argv[0] is in use would
allow to skip the pathname argument.

This patch uses an unused auxiliary vector, AT_FLAGS, to add a
flag to inform interpreter if the preserve-argv[0] is enabled.

Note by Helge Deller:
The real-world user of this patch is qemu-user, which needs to know
if it has to preserve the argv[0]. See Debian bug #970460.

Signed-off-by: Laurent Vivier &lt;laurent@vivier.eu&gt;
Reviewed-by: YunQiang Su &lt;ysu@wavecomp.com&gt;
URL: http://bugs.debian.org/970460
Signed-off-by: Helge Deller &lt;deller@gmx.de&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
It can be useful to the interpreter to know which flags are in use.

For instance, knowing if the preserve-argv[0] is in use would
allow to skip the pathname argument.

This patch uses an unused auxiliary vector, AT_FLAGS, to add a
flag to inform interpreter if the preserve-argv[0] is enabled.

Note by Helge Deller:
The real-world user of this patch is qemu-user, which needs to know
if it has to preserve the argv[0]. See Debian bug #970460.

Signed-off-by: Laurent Vivier &lt;laurent@vivier.eu&gt;
Reviewed-by: YunQiang Su &lt;ysu@wavecomp.com&gt;
URL: http://bugs.debian.org/970460
Signed-off-by: Helge Deller &lt;deller@gmx.de&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>elf_prstatus: collect the common part (everything before pr_reg) into a struct</title>
<updated>2021-01-06T13:38:29+00:00</updated>
<author>
<name>Al Viro</name>
<email>viro@zeniv.linux.org.uk</email>
</author>
<published>2020-06-13T04:08:44+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=f2485a2dc9f0f30fbdd013ad5772975100c71360'/>
<id>f2485a2dc9f0f30fbdd013ad5772975100c71360</id>
<content type='text'>
Preparations to doing i386 compat elf_prstatus sanely - rather than duplicating
the beginning of compat_elf_prstatus, take these fields into a separate
structure (compat_elf_prstatus_common), so that it could be reused.  Due to
the incestous relationship between binfmt_elf.c and compat_binfmt_elf.c we
need the same shape change done to native struct elf_prstatus, gathering the
fields prior to pr_reg into a new structure (struct elf_prstatus_common).

Fortunately, offset of pr_reg is always a multiple of 16 with no padding
right before it, so it's possible to turn all the stuff prior to it into
a single member without disturbing the layout.

[build fix from Geert Uytterhoeven folded in]

Signed-off-by: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Preparations to doing i386 compat elf_prstatus sanely - rather than duplicating
the beginning of compat_elf_prstatus, take these fields into a separate
structure (compat_elf_prstatus_common), so that it could be reused.  Due to
the incestous relationship between binfmt_elf.c and compat_binfmt_elf.c we
need the same shape change done to native struct elf_prstatus, gathering the
fields prior to pr_reg into a new structure (struct elf_prstatus_common).

Fortunately, offset of pr_reg is always a multiple of 16 with no padding
right before it, so it's possible to turn all the stuff prior to it into
a single member without disturbing the layout.

[build fix from Geert Uytterhoeven folded in]

Signed-off-by: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>binfmt_elf: partially sanitize PRSTATUS_SIZE and SET_PR_FPVALID</title>
<updated>2021-01-04T23:27:37+00:00</updated>
<author>
<name>Al Viro</name>
<email>viro@zeniv.linux.org.uk</email>
</author>
<published>2020-06-23T00:14:02+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=8a00dd0012f383fc0c39b169b694dc15236cec7c'/>
<id>8a00dd0012f383fc0c39b169b694dc15236cec7c</id>
<content type='text'>
On 64bit architectures that support 32bit processes there are
two possible layouts for NT_PRSTATUS note in ELF coredumps.
For one thing, several fields are 64bit for native processes
and 32bit for compat ones (pr_sigpend, etc.).  For another,
the register dump is obviously different - the size and number
of registers are not going to be the same for 32bit and 64bit
variants of processor.

Usually that's handled by having two structures - elf_prstatus
for native layout and compat_elf_prstatus for 32bit one.
32bit processes are handled by fs/compat_binfmt_elf.c, which
defines a macro called 'elf_prstatus' that expands to compat_elf_prstatus.
Then it includes fs/binfmt_elf.c, which makes all references to
struct elf_prstatus to be textually replaced with struct
compat_elf_prstatus.  Ugly and somewhat brittle, but it works.

However, amd64 is worse - there are _three_ possible layouts.
One for native 64bit processes, another for i386 (32bit) processes
and yet another for x32 (32bit address space with full 64bit
registers).

Both i386 and x32 processes are handled by fs/compat_binfmt_elf.c,
with usual compat_binfmt_elf.c trickery.  However, the layouts
for i386 and x32 are not identical - they have the common beginning,
but the register dump part (pr_reg) is bigger on x32.  Worse, pr_reg
is not the last field - it's followed by int pr_fpvalid, so that
field ends up at different offsets for i386 and x32 layouts.

Fortunately, there's not much code that cares about any of that -
it's all encapsulated in fill_thread_core_info().  Since x32
variant is bigger, we define compat_elf_prstatus to match that
layout.  That way i386 processes have enough space to fit
their layout into.

Moreover, since these layouts are identical prior to pr_reg,
we don't need to distinguish x32 and i386 cases when we are
setting the fields prior to pr_reg.

Filling pr_reg itself is done by calling -&gt;get() method of
appropriate regset, and that method knows what layout (and size)
to use.

We do need to distinguish x32 and i386 cases only for two
things: setting -&gt;pr_fpvalid (offset differs for x32 and
i386) and choosing the right size for our note.

The way it's done is Not Nice, for the lack of more accurate
printable description.  There are two macros (PRSTATUS_SIZE and
SET_PR_FPVALID), that default essentially to sizeof(struct elf_prstatus)
and (S)-&gt;pr_fpvalid = 1.  On x86 asm/compat.h provides its own
variants.

Unfortunately, quite a few things go wrong there:
	* PRSTATUS_SIZE doesn't use the normal test for process
being an x32 one; it compares the size reported by regset with
the size of pr_reg.
	* it hardcodes the sizes of x32 and i386 variants (296 and 144
resp.), so if some change in includes leads to asm/compat.h pulled
in by fs/binfmt_elf.c we are in trouble - it will end up using
the size of x32 variant for 64bit processes.
	* it's in the wrong place; asm/compat.h couldn't define
the structure for i386 layout, since it lacks quite a few types
needed for it.  Hardcoded sizes are largely due to that.

The proper fix would be to have an explicitly defined i386 variant
of structure and have PRSTATUS_SIZE/SET_PR_FPVALID check for
TIF_X32 to choose the variant that should be used.  Unfortunately,
that requires some manipulations of headers; we'll do that later
in the series, but for now let's go with the minimal variant -
rename PRSTATUS_SIZE in asm/compat.h to COMPAT_PRSTATUS_SIZE,
have fs/compat_binfmt_elf.c define PRSTATUS_SIZE to COMPAT_PRSTATUS_SIZE
and use the normal TIF_X32 check in that macro.  The size of i386 variant
is kept hardcoded for now.  Similar story for SET_PR_FPVALID.

Signed-off-by: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
On 64bit architectures that support 32bit processes there are
two possible layouts for NT_PRSTATUS note in ELF coredumps.
For one thing, several fields are 64bit for native processes
and 32bit for compat ones (pr_sigpend, etc.).  For another,
the register dump is obviously different - the size and number
of registers are not going to be the same for 32bit and 64bit
variants of processor.

Usually that's handled by having two structures - elf_prstatus
for native layout and compat_elf_prstatus for 32bit one.
32bit processes are handled by fs/compat_binfmt_elf.c, which
defines a macro called 'elf_prstatus' that expands to compat_elf_prstatus.
Then it includes fs/binfmt_elf.c, which makes all references to
struct elf_prstatus to be textually replaced with struct
compat_elf_prstatus.  Ugly and somewhat brittle, but it works.

However, amd64 is worse - there are _three_ possible layouts.
One for native 64bit processes, another for i386 (32bit) processes
and yet another for x32 (32bit address space with full 64bit
registers).

Both i386 and x32 processes are handled by fs/compat_binfmt_elf.c,
with usual compat_binfmt_elf.c trickery.  However, the layouts
for i386 and x32 are not identical - they have the common beginning,
but the register dump part (pr_reg) is bigger on x32.  Worse, pr_reg
is not the last field - it's followed by int pr_fpvalid, so that
field ends up at different offsets for i386 and x32 layouts.

Fortunately, there's not much code that cares about any of that -
it's all encapsulated in fill_thread_core_info().  Since x32
variant is bigger, we define compat_elf_prstatus to match that
layout.  That way i386 processes have enough space to fit
their layout into.

Moreover, since these layouts are identical prior to pr_reg,
we don't need to distinguish x32 and i386 cases when we are
setting the fields prior to pr_reg.

Filling pr_reg itself is done by calling -&gt;get() method of
appropriate regset, and that method knows what layout (and size)
to use.

We do need to distinguish x32 and i386 cases only for two
things: setting -&gt;pr_fpvalid (offset differs for x32 and
i386) and choosing the right size for our note.

The way it's done is Not Nice, for the lack of more accurate
printable description.  There are two macros (PRSTATUS_SIZE and
SET_PR_FPVALID), that default essentially to sizeof(struct elf_prstatus)
and (S)-&gt;pr_fpvalid = 1.  On x86 asm/compat.h provides its own
variants.

Unfortunately, quite a few things go wrong there:
	* PRSTATUS_SIZE doesn't use the normal test for process
being an x32 one; it compares the size reported by regset with
the size of pr_reg.
	* it hardcodes the sizes of x32 and i386 variants (296 and 144
resp.), so if some change in includes leads to asm/compat.h pulled
in by fs/binfmt_elf.c we are in trouble - it will end up using
the size of x32 variant for 64bit processes.
	* it's in the wrong place; asm/compat.h couldn't define
the structure for i386 layout, since it lacks quite a few types
needed for it.  Hardcoded sizes are largely due to that.

The proper fix would be to have an explicitly defined i386 variant
of structure and have PRSTATUS_SIZE/SET_PR_FPVALID check for
TIF_X32 to choose the variant that should be used.  Unfortunately,
that requires some manipulations of headers; we'll do that later
in the series, but for now let's go with the minimal variant -
rename PRSTATUS_SIZE in asm/compat.h to COMPAT_PRSTATUS_SIZE,
have fs/compat_binfmt_elf.c define PRSTATUS_SIZE to COMPAT_PRSTATUS_SIZE
and use the normal TIF_X32 check in that macro.  The size of i386 variant
is kept hardcoded for now.  Similar story for SET_PR_FPVALID.

Signed-off-by: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge branch 'exec-for-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace</title>
<updated>2020-12-16T03:29:43+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2020-12-16T03:29:43+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=faf145d6f3f3d6f2c066f65602ba9d0a03106915'/>
<id>faf145d6f3f3d6f2c066f65602ba9d0a03106915</id>
<content type='text'>
Pull execve updates from Eric Biederman:
 "This set of changes ultimately fixes the interaction of posix file
  lock and exec. Fundamentally most of the change is just moving where
  unshare_files is called during exec, and tweaking the users of
  files_struct so that the count of files_struct is not unnecessarily
  played with.

  Along the way fcheck and related helpers were renamed to more
  accurately reflect what they do.

  There were also many other small changes that fell out, as this is the
  first time in a long time much of this code has been touched.

  Benchmarks haven't turned up any practical issues but Al Viro has
  observed a possibility for a lot of pounding on task_lock. So I have
  some changes in progress to convert put_files_struct to always rcu
  free files_struct. That wasn't ready for the merge window so that will
  have to wait until next time"

* 'exec-for-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (27 commits)
  exec: Move io_uring_task_cancel after the point of no return
  coredump: Document coredump code exclusively used by cell spufs
  file: Remove get_files_struct
  file: Rename __close_fd_get_file close_fd_get_file
  file: Replace ksys_close with close_fd
  file: Rename __close_fd to close_fd and remove the files parameter
  file: Merge __alloc_fd into alloc_fd
  file: In f_dupfd read RLIMIT_NOFILE once.
  file: Merge __fd_install into fd_install
  proc/fd: In fdinfo seq_show don't use get_files_struct
  bpf/task_iter: In task_file_seq_get_next use task_lookup_next_fd_rcu
  proc/fd: In proc_readfd_common use task_lookup_next_fd_rcu
  file: Implement task_lookup_next_fd_rcu
  kcmp: In get_file_raw_ptr use task_lookup_fd_rcu
  proc/fd: In tid_fd_mode use task_lookup_fd_rcu
  file: Implement task_lookup_fd_rcu
  file: Rename fcheck lookup_fd_rcu
  file: Replace fcheck_files with files_lookup_fd_rcu
  file: Factor files_lookup_fd_locked out of fcheck_files
  file: Rename __fcheck_files to files_lookup_fd_raw
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull execve updates from Eric Biederman:
 "This set of changes ultimately fixes the interaction of posix file
  lock and exec. Fundamentally most of the change is just moving where
  unshare_files is called during exec, and tweaking the users of
  files_struct so that the count of files_struct is not unnecessarily
  played with.

  Along the way fcheck and related helpers were renamed to more
  accurately reflect what they do.

  There were also many other small changes that fell out, as this is the
  first time in a long time much of this code has been touched.

  Benchmarks haven't turned up any practical issues but Al Viro has
  observed a possibility for a lot of pounding on task_lock. So I have
  some changes in progress to convert put_files_struct to always rcu
  free files_struct. That wasn't ready for the merge window so that will
  have to wait until next time"

* 'exec-for-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (27 commits)
  exec: Move io_uring_task_cancel after the point of no return
  coredump: Document coredump code exclusively used by cell spufs
  file: Remove get_files_struct
  file: Rename __close_fd_get_file close_fd_get_file
  file: Replace ksys_close with close_fd
  file: Rename __close_fd to close_fd and remove the files parameter
  file: Merge __alloc_fd into alloc_fd
  file: In f_dupfd read RLIMIT_NOFILE once.
  file: Merge __fd_install into fd_install
  proc/fd: In fdinfo seq_show don't use get_files_struct
  bpf/task_iter: In task_file_seq_get_next use task_lookup_next_fd_rcu
  proc/fd: In proc_readfd_common use task_lookup_next_fd_rcu
  file: Implement task_lookup_next_fd_rcu
  kcmp: In get_file_raw_ptr use task_lookup_fd_rcu
  proc/fd: In tid_fd_mode use task_lookup_fd_rcu
  file: Implement task_lookup_fd_rcu
  file: Rename fcheck lookup_fd_rcu
  file: Replace fcheck_files with files_lookup_fd_rcu
  file: Factor files_lookup_fd_locked out of fcheck_files
  file: Rename __fcheck_files to files_lookup_fd_raw
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'x86_cleanups_for_v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip</title>
<updated>2020-12-14T21:45:26+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2020-12-14T21:45:26+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=405f868f13daf7bae85e6fec143121c27d52cdb4'/>
<id>405f868f13daf7bae85e6fec143121c27d52cdb4</id>
<content type='text'>
Pull x86 cleanups from Borislav Petkov:
 "Another branch with a nicely negative diffstat, just the way I
  like 'em:

   - Remove all uses of TIF_IA32 and TIF_X32 and reclaim the two bits in
     the end (Gabriel Krisman Bertazi)

   - All kinds of minor cleanups all over the tree"

* tag 'x86_cleanups_for_v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits)
  x86/ia32_signal: Propagate __user annotation properly
  x86/alternative: Update text_poke_bp() kernel-doc comment
  x86/PCI: Make a kernel-doc comment a normal one
  x86/asm: Drop unused RDPID macro
  x86/boot/compressed/64: Use TEST %reg,%reg instead of CMP $0,%reg
  x86/head64: Remove duplicate include
  x86/mm: Declare 'start' variable where it is used
  x86/head/64: Remove unused GET_CR2_INTO() macro
  x86/boot: Remove unused finalize_identity_maps()
  x86/uaccess: Document copy_from_user_nmi()
  x86/dumpstack: Make show_trace_log_lvl() static
  x86/mtrr: Fix a kernel-doc markup
  x86/setup: Remove unused MCA variables
  x86, libnvdimm/test: Remove COPY_MC_TEST
  x86: Reclaim TIF_IA32 and TIF_X32
  x86/mm: Convert mmu context ia32_compat into a proper flags field
  x86/elf: Use e_machine to check for x32/ia32 in setup_additional_pages()
  elf: Expose ELF header on arch_setup_additional_pages()
  x86/elf: Use e_machine to select start_thread for x32
  elf: Expose ELF header in compat_start_thread()
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull x86 cleanups from Borislav Petkov:
 "Another branch with a nicely negative diffstat, just the way I
  like 'em:

   - Remove all uses of TIF_IA32 and TIF_X32 and reclaim the two bits in
     the end (Gabriel Krisman Bertazi)

   - All kinds of minor cleanups all over the tree"

* tag 'x86_cleanups_for_v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits)
  x86/ia32_signal: Propagate __user annotation properly
  x86/alternative: Update text_poke_bp() kernel-doc comment
  x86/PCI: Make a kernel-doc comment a normal one
  x86/asm: Drop unused RDPID macro
  x86/boot/compressed/64: Use TEST %reg,%reg instead of CMP $0,%reg
  x86/head64: Remove duplicate include
  x86/mm: Declare 'start' variable where it is used
  x86/head/64: Remove unused GET_CR2_INTO() macro
  x86/boot: Remove unused finalize_identity_maps()
  x86/uaccess: Document copy_from_user_nmi()
  x86/dumpstack: Make show_trace_log_lvl() static
  x86/mtrr: Fix a kernel-doc markup
  x86/setup: Remove unused MCA variables
  x86, libnvdimm/test: Remove COPY_MC_TEST
  x86: Reclaim TIF_IA32 and TIF_X32
  x86/mm: Convert mmu context ia32_compat into a proper flags field
  x86/elf: Use e_machine to check for x32/ia32 in setup_additional_pages()
  elf: Expose ELF header on arch_setup_additional_pages()
  x86/elf: Use e_machine to select start_thread for x32
  elf: Expose ELF header in compat_start_thread()
  ...
</pre>
</div>
</content>
</entry>
</feed>
