linux-stable.git/arch/um/kernel, branch linux-3.4.y Linux kernel stable tree vm: add VM_FAULT_SIGSEGV handling support 2015-04-14T09:33:57+00:00 Linus Torvalds torvalds@linux-foundation.org 2015-01-29T18:51:32+00:00 a10ca0dbc2bcf3383fa42dcfeca055f7b5fe1106 commit 33692f27597fcab536d7cbbcc8f52905133e4aa7 upstream. The core VM already knows about VM_FAULT_SIGBUS, but cannot return a "you should SIGSEGV" error, because the SIGSEGV case was generally handled by the caller - usually the architecture fault handler. That results in lots of duplication - all the architecture fault handlers end up doing very similar "look up vma, check permissions, do retries etc" - but it generally works. However, there are cases where the VM actually wants to SIGSEGV, and applications _expect_ SIGSEGV. In particular, when accessing the stack guard page, libsigsegv expects a SIGSEGV. And it usually got one, because the stack growth is handled by that duplicated architecture fault handler. However, when the generic VM layer started propagating the error return from the stack expansion in commit fee7e49d4514 ("mm: propagate error from stack expansion even for guard page"), that now exposed the existing VM_FAULT_SIGBUS result to user space. And user space really expected SIGSEGV, not SIGBUS. To fix that case, we need to add a VM_FAULT_SIGSEGV, and teach all those duplicate architecture fault handlers about it. They all already have the code to handle SIGSEGV, so it's about just tying that new return value to the existing code, but it's all a bit annoying. This is the mindless minimal patch to do this. A more extensive patch would be to try to gather up the mostly shared fault handling logic into one generic helper routine, and long-term we really should do that cleanup. Just from this patch, you can generally see that most architectures just copied (directly or indirectly) the old x86 way of doing things, but in the meantime that original x86 model has been improved to hold the VM semaphore for shorter times etc and to handle VM_FAULT_RETRY and other "newer" things, so it would be a good idea to bring all those improvements to the generic case and teach other architectures about them too. Reported-and-tested-by: Takashi Iwai <tiwai@suse.de> Tested-by: Jan Engelhardt <jengelh@inai.de> Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com> # "s390 still compiles and boots" Cc: linux-arch@vger.kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> [bwh: Backported to 3.2: - Adjust filenames, context - Drop arc, metag, nios2 and lustre changes - For sh, patch both 32-bit and 64-bit implementations to use goto bad_area - For s390, pass int_code and trans_exc_code as arguments to do_no_context() and do_sigsegv()] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> [lizf: Backported to 3.4: - adjust context in arch/power/mm/fault.c - apply the original change in upstream commit for s390] Signed-off-by: Zefan Li <lizefan@huawei.com> 
commit 33692f27597fcab536d7cbbcc8f52905133e4aa7 upstream.

The core VM already knows about VM_FAULT_SIGBUS, but cannot return a
"you should SIGSEGV" error, because the SIGSEGV case was generally
handled by the caller - usually the architecture fault handler.

That results in lots of duplication - all the architecture fault
handlers end up doing very similar "look up vma, check permissions, do
retries etc" - but it generally works.  However, there are cases where
the VM actually wants to SIGSEGV, and applications _expect_ SIGSEGV.

In particular, when accessing the stack guard page, libsigsegv expects a
SIGSEGV.  And it usually got one, because the stack growth is handled by
that duplicated architecture fault handler.

However, when the generic VM layer started propagating the error return
from the stack expansion in commit fee7e49d4514 ("mm: propagate error
from stack expansion even for guard page"), that now exposed the
existing VM_FAULT_SIGBUS result to user space.  And user space really
expected SIGSEGV, not SIGBUS.

To fix that case, we need to add a VM_FAULT_SIGSEGV, and teach all those
duplicate architecture fault handlers about it.  They all already have
the code to handle SIGSEGV, so it's about just tying that new return
value to the existing code, but it's all a bit annoying.

This is the mindless minimal patch to do this.  A more extensive patch
would be to try to gather up the mostly shared fault handling logic into
one generic helper routine, and long-term we really should do that
cleanup.

Just from this patch, you can generally see that most architectures just
copied (directly or indirectly) the old x86 way of doing things, but in
the meantime that original x86 model has been improved to hold the VM
semaphore for shorter times etc and to handle VM_FAULT_RETRY and other
"newer" things, so it would be a good idea to bring all those
improvements to the generic case and teach other architectures about
them too.

Reported-and-tested-by: Takashi Iwai <tiwai@suse.de>
Tested-by: Jan Engelhardt <jengelh@inai.de>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com> # "s390 still compiles and boots"
Cc: linux-arch@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[bwh: Backported to 3.2:
 - Adjust filenames, context
 - Drop arc, metag, nios2 and lustre changes
 - For sh, patch both 32-bit and 64-bit implementations to use goto bad_area
 - For s390, pass int_code and trans_exc_code as arguments to do_no_context()
   and do_sigsegv()]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
[lizf: Backported to 3.4:
 - adjust context in arch/power/mm/fault.c
 - apply the original change in upstream commit for s390]
Signed-off-by: Zefan Li <lizefan@huawei.com>
uml: check length in exitcode_proc_write() 2013-11-13T03:01:49+00:00 Dan Carpenter dan.carpenter@oracle.com 2013-10-29T19:06:04+00:00 cc51af932905754ad594f8d1fc02d61073b7236f commit 201f99f170df14ba52ea4c52847779042b7a623b upstream. We don't cap the size of buffer from the user so we could write past the end of the array here. Only root can write to this file. Reported-by: Nico Golde <nico@ngolde.de> Reported-by: Fabian Yamaguchi <fabs@goesec.de> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 201f99f170df14ba52ea4c52847779042b7a623b upstream.

We don't cap the size of buffer from the user so we could write past the
end of the array here.  Only root can write to this file.

Reported-by: Nico Golde <nico@ngolde.de>
Reported-by: Fabian Yamaguchi <fabs@goesec.de>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
um: uml_setup_stubs': warning: unused variable 'pages' 2012-04-09T22:13:45+00:00 Boaz Harrosh bharrosh@panasas.com 2012-03-27T02:18:22+00:00 657b12d3a1508a3f06f7afe21d5dda7252279520 Fix the following gcc complain arch/um/kernel/skas/mmu.c: In function 'uml_setup_stubs': arch/um/kernel/skas/mmu.c:106:16: warning: unused variable 'pages' [-Wunused-variable] Signed-Signed-off-by: Boaz Harrosh <bharrosh@panasas.com> Signed-off-by: Richard Weinberger <richard@nod.at> 
Fix the following gcc complain
arch/um/kernel/skas/mmu.c: In function 'uml_setup_stubs':
arch/um/kernel/skas/mmu.c:106:16: warning: unused variable 'pages' [-Wunused-variable]

Signed-Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
um: Use asm-generic/switch_to.h 2012-04-09T22:13:45+00:00 Richard Weinberger richard@nod.at 2012-03-29T17:10:42+00:00 76b278edd99fb55525fcf2706095e388bd3d122c Signed-off-by: Richard Weinberger <richard@nod.at> 
Signed-off-by: Richard Weinberger <richard@nod.at>
um: fix linker script generation 2012-04-09T17:59:00+00:00 Al Viro viro@zeniv.linux.org.uk 2012-04-09T17:59:00+00:00 3cb42092ff02edec34bf936b7400b1f1efc8ca43 while we can't just use -U$(SUBARCH), we still need to kill idiotic define (implicit -Di386=1), both for SUBARCH=i386 and SUBARCH=x86/CONFIG_64BIT=n builds. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> 
while we can't just use -U$(SUBARCH), we still need to kill idiotic define
(implicit -Di386=1), both for SUBARCH=i386 and SUBARCH=x86/CONFIG_64BIT=n
builds.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
remove references to cpu_*_map in arch/ 2012-03-29T05:08:30+00:00 Rusty Russell rusty@rustcorp.com.au 2012-03-29T05:08:30+00:00 0b5f9c005def154f9c21f9be0223b65b50d54368 This has been obsolescent for a while; time for the final push. In adjacent context, replaced old cpus_* with cpumask_*. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Acked-by: David S. Miller <davem@davemloft.net> (arch/sparc) Acked-by: Chris Metcalf <cmetcalf@tilera.com> (arch/tile) Cc: user-mode-linux-devel@lists.sourceforge.net Cc: Russell King <linux@arm.linux.org.uk> Cc: linux-arm-kernel@lists.infradead.org Cc: Richard Kuo <rkuo@codeaurora.org> Cc: linux-hexagon@vger.kernel.org Cc: Ralf Baechle <ralf@linux-mips.org> Cc: linux-mips@linux-mips.org Cc: Kyle McMartin <kyle@mcmartin.ca> Cc: Helge Deller <deller@gmx.de> Cc: sparclinux@vger.kernel.org 
This has been obsolescent for a while; time for the final push.

In adjacent context, replaced old cpus_* with cpumask_*.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: David S. Miller <davem@davemloft.net> (arch/sparc)
Acked-by: Chris Metcalf <cmetcalf@tilera.com> (arch/tile)
Cc: user-mode-linux-devel@lists.sourceforge.net
Cc: Russell King <linux@arm.linux.org.uk>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: linux-hexagon@vger.kernel.org
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Helge Deller <deller@gmx.de>
Cc: sparclinux@vger.kernel.org
Merge branch 'for-linus-3.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml 2012-03-28T01:29:53+00:00 Linus Torvalds torvalds@linux-foundation.org 2012-03-28T01:29:53+00:00 fa453a625de5b8ee9ada0a5b329df3f88751c615 Pull UML changes from Richard Weinberger: "Mostly bug fixes and cleanups" * 'for-linus-3.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml: (35 commits) um: Update defconfig um: Switch to large mcmodel on x86_64 MTD: Relax dependencies um: Wire CONFIG_GENERIC_IO up um: Serve io_remap_pfn_range() Introduce CONFIG_GENERIC_IO um: allow SUBARCH=x86 um: most of the SUBARCH uses can be killed um: deadlock in line_write_interrupt() um: don't bother trying to rebuild CHECKFLAGS for USER_OBJS um: use the right ifdef around exports in user_syms.c um: a bunch of headers can be killed by using generic-y um: ptrace-generic.h doesn't need user.h um: kill HOST_TASK_PID um: remove pointless include of asm/fixmap.h from asm/pgtable.h um: asm-offsets.h might as well come from underlying arch... um: merge processor_{32,64}.h a bit... um: switch close_chan() to struct line um: race fix: initialize delayed_work *before* registering IRQ um: line->have_irq is never checked... ... 
Pull UML changes from Richard Weinberger:
 "Mostly bug fixes and cleanups"

* 'for-linus-3.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml: (35 commits)
  um: Update defconfig
  um: Switch to large mcmodel on x86_64
  MTD: Relax dependencies
  um: Wire CONFIG_GENERIC_IO up
  um: Serve io_remap_pfn_range()
  Introduce CONFIG_GENERIC_IO
  um: allow SUBARCH=x86
  um: most of the SUBARCH uses can be killed
  um: deadlock in line_write_interrupt()
  um: don't bother trying to rebuild CHECKFLAGS for USER_OBJS
  um: use the right ifdef around exports in user_syms.c
  um: a bunch of headers can be killed by using generic-y
  um: ptrace-generic.h doesn't need user.h
  um: kill HOST_TASK_PID
  um: remove pointless include of asm/fixmap.h from asm/pgtable.h
  um: asm-offsets.h might as well come from underlying arch...
  um: merge processor_{32,64}.h a bit...
  um: switch close_chan() to struct line
  um: race fix: initialize delayed_work *before* registering IRQ
  um: line->have_irq is never checked...
  ...
um: most of the SUBARCH uses can be killed 2012-03-24T23:29:56+00:00 Al Viro viro@zeniv.linux.org.uk 2012-02-11T10:39:56+00:00 dc5be20a6454312d395dbf07eb2218090a03ae24 Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> [richard@nod.at: Re-export SUBARCH in arch/um/Makefile] Signed-off-by: Richard Weinberger <richard@nod.at> 
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
[richard@nod.at: Re-export SUBARCH in arch/um/Makefile]
Signed-off-by: Richard Weinberger <richard@nod.at>
um: kill HOST_TASK_PID 2012-03-24T23:29:55+00:00 Al Viro viro@zeniv.linux.org.uk 2012-01-30T21:30:48+00:00 c2220b2a124d2fe7b0074b23680177c8e905a76c just provide get_current_pid() to the userland side of things instead of get_current() + manual poking in its results Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Richard Weinberger <richard@nod.at> 
just provide get_current_pid() to the userland side of things
instead of get_current() + manual poking in its results

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Richard Weinberger <richard@nod.at>
um: irq: Remove IRQF_DISABLED 2012-03-24T23:29:52+00:00 Yong Zhang yong.zhang0@gmail.com 2011-09-22T08:58:46+00:00 c0b79a90b1556a7e51d7a49a655eb60306f6258d Since commit [e58aa3d2: genirq: Run irq handlers with interrupts disabled], We run all interrupt handlers with interrupts disabled and we even check and yell when an interrupt handler returns with interrupts enabled (see commit [b738a50a: genirq: Warn when handler enables interrupts]). So now this flag is a NOOP and can be removed. Signed-off-by: Yong Zhang <yong.zhang0@gmail.com> Signed-off-by: Richard Weinberger <richard@nod.at> 
Since commit [e58aa3d2: genirq: Run irq handlers with interrupts disabled],
We run all interrupt handlers with interrupts disabled
and we even check and yell when an interrupt handler
returns with interrupts enabled (see commit [b738a50a:
genirq: Warn when handler enables interrupts]).

So now this flag is a NOOP and can be removed.

Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
Signed-off-by: Richard Weinberger <richard@nod.at>