From 33692f27597fcab536d7cbbcc8f52905133e4aa7 Mon Sep 17 00:00:00 2001
From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Thu, 29 Jan 2015 10:51:32 -0800
Subject: [PATCH] vm: add VM_FAULT_SIGSEGV handling support
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
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
arch/alpha/mm/fault.c | 2 ++
arch/arc/mm/fault.c | 2 ++
arch/avr32/mm/fault.c | 2 ++
arch/cris/mm/fault.c | 2 ++
arch/frv/mm/fault.c | 2 ++
arch/ia64/mm/fault.c | 2 ++
arch/m32r/mm/fault.c | 2 ++
arch/m68k/mm/fault.c | 2 ++
arch/metag/mm/fault.c | 2 ++
arch/microblaze/mm/fault.c | 2 ++
arch/mips/mm/fault.c | 2 ++
arch/mn10300/mm/fault.c | 2 ++
arch/nios2/mm/fault.c | 2 ++
arch/openrisc/mm/fault.c | 2 ++
arch/parisc/mm/fault.c | 2 ++
arch/powerpc/mm/copro_fault.c | 2 +-
arch/powerpc/mm/fault.c | 2 ++
arch/s390/mm/fault.c | 6 ++++++
arch/score/mm/fault.c | 2 ++
arch/sh/mm/fault.c | 2 ++
arch/sparc/mm/fault_32.c | 2 ++
arch/sparc/mm/fault_64.c | 2 ++
arch/tile/mm/fault.c | 2 ++
arch/um/kernel/trap.c | 2 ++
arch/x86/mm/fault.c | 2 ++
arch/xtensa/mm/fault.c | 2 ++
drivers/staging/lustre/lustre/llite/vvp_io.c | 2 +-
include/linux/mm.h | 6 ++++--
mm/gup.c | 4 ++--
mm/ksm.c | 2 +-
30 files changed, 63 insertions(+), 7 deletions(-)
diff --git a/arch/alpha/mm/fault.c b/arch/alpha/mm/fault.c
index 98838a05ba6d89..9d0ac091a52a7d 100644
--- a/arch/alpha/mm/fault.c
+++ b/arch/alpha/mm/fault.c
@@ -156,6 +156,8 @@ retry:
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM)
goto out_of_memory;
+ else if (fault & VM_FAULT_SIGSEGV)
+ goto bad_area;
else if (fault & VM_FAULT_SIGBUS)
goto do_sigbus;
BUG();
diff --git a/arch/arc/mm/fault.c b/arch/arc/mm/fault.c
index 6f7e3a68803a09..0f8df3b5b1b366 100644
--- a/arch/arc/mm/fault.c
+++ b/arch/arc/mm/fault.c
@@ -161,6 +161,8 @@ good_area:
if (fault & VM_FAULT_OOM)
goto out_of_memory;
+ else if (fault & VM_FAULT_SIGSEV)
+ goto bad_area;
else if (fault & VM_FAULT_SIGBUS)
goto do_sigbus;
diff --git a/arch/avr32/mm/fault.c b/arch/avr32/mm/fault.c
index 0eca9332719507..d223a8b57c1eaa 100644
--- a/arch/avr32/mm/fault.c
+++ b/arch/avr32/mm/fault.c
@@ -142,6 +142,8 @@ good_area:
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM)
goto out_of_memory;
+ else if (fault & VM_FAULT_SIGSEGV)
+ goto bad_area;
else if (fault & VM_FAULT_SIGBUS)
goto do_sigbus;
BUG();
diff --git a/arch/cris/mm/fault.c b/arch/cris/mm/fault.c
index 1790f22e71a21a..2686a7aa8ec82c 100644
--- a/arch/cris/mm/fault.c
+++ b/arch/cris/mm/fault.c
@@ -176,6 +176,8 @@ retry:
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM)
goto out_of_memory;
+ else if (fault & VM_FAULT_SIGSEGV)
+ goto bad_area;
else if (fault & VM_FAULT_SIGBUS)
goto do_sigbus;
BUG();
diff --git a/arch/frv/mm/fault.c b/arch/frv/mm/fault.c
index 9a66372fc7c760..ec4917ddf67872 100644
--- a/arch/frv/mm/fault.c
+++ b/arch/frv/mm/fault.c
@@ -168,6 +168,8 @@ asmlinkage void do_page_fault(int datammu, unsigned long esr0, unsigned long ear
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM)
goto out_of_memory;
+ else if (fault & VM_FAULT_SIGSEGV)
+ goto bad_area;
else if (fault & VM_FAULT_SIGBUS)
goto do_sigbus;
BUG();
diff --git a/arch/ia64/mm/fault.c b/arch/ia64/mm/fault.c
index 7225dad87094d8..ba5ba7accd0d6b 100644
--- a/arch/ia64/mm/fault.c
+++ b/arch/ia64/mm/fault.c
@@ -172,6 +172,8 @@ retry:
*/
if (fault & VM_FAULT_OOM) {
goto out_of_memory;
+ } else if (fault & VM_FAULT_SIGSEGV) {
+ goto bad_area;
} else if (fault & VM_FAULT_SIGBUS) {
signal = SIGBUS;
goto bad_area;
diff --git a/arch/m32r/mm/fault.c b/arch/m32r/mm/fault.c
index e9c6a8014bd647..e3d4d4890104cc 100644
--- a/arch/m32r/mm/fault.c
+++ b/arch/m32r/mm/fault.c
@@ -200,6 +200,8 @@ good_area:
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM)
goto out_of_memory;
+ else if (fault & VM_FAULT_SIGSEGV)
+ goto bad_area;
else if (fault & VM_FAULT_SIGBUS)
goto do_sigbus;
BUG();
diff --git a/arch/m68k/mm/fault.c b/arch/m68k/mm/fault.c
index 2bd7487440c455..b2f04aee46ecc2 100644
--- a/arch/m68k/mm/fault.c
+++ b/arch/m68k/mm/fault.c
@@ -145,6 +145,8 @@ good_area:
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM)
goto out_of_memory;
+ else if (fault & VM_FAULT_SIGSEGV)
+ goto map_err;
else if (fault & VM_FAULT_SIGBUS)
goto bus_err;
BUG();
diff --git a/arch/metag/mm/fault.c b/arch/metag/mm/fault.c
index 332680e5ebf23c..2de5dc695a87fa 100644
--- a/arch/metag/mm/fault.c
+++ b/arch/metag/mm/fault.c
@@ -141,6 +141,8 @@ good_area:
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM)
goto out_of_memory;
+ else if (fault & VM_FAULT_SIGSEGV)
+ goto bad_area;
else if (fault & VM_FAULT_SIGBUS)
goto do_sigbus;
BUG();
diff --git a/arch/microblaze/mm/fault.c b/arch/microblaze/mm/fault.c
index fa4cf52aa7a6d3..d46a5ebb7570e0 100644
--- a/arch/microblaze/mm/fault.c
+++ b/arch/microblaze/mm/fault.c
@@ -224,6 +224,8 @@ good_area:
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM)
goto out_of_memory;
+ else if (fault & VM_FAULT_SIGSEGV)
+ goto bad_area;
else if (fault & VM_FAULT_SIGBUS)
goto do_sigbus;
BUG();
diff --git a/arch/mips/mm/fault.c b/arch/mips/mm/fault.c
index becc42bb18495a..70ab5d66433269 100644
--- a/arch/mips/mm/fault.c
+++ b/arch/mips/mm/fault.c
@@ -158,6 +158,8 @@ good_area:
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM)
goto out_of_memory;
+ else if (fault & VM_FAULT_SIGSEGV)
+ goto bad_area;
else if (fault & VM_FAULT_SIGBUS)
goto do_sigbus;
BUG();
diff --git a/arch/mn10300/mm/fault.c b/arch/mn10300/mm/fault.c
index 3516cbdf1ee93a..0c2cc5d39c8e37 100644
--- a/arch/mn10300/mm/fault.c
+++ b/arch/mn10300/mm/fault.c
@@ -262,6 +262,8 @@ good_area:
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM)
goto out_of_memory;
+ else if (fault & VM_FAULT_SIGSEGV)
+ goto bad_area;
else if (fault & VM_FAULT_SIGBUS)
goto do_sigbus;
BUG();
diff --git a/arch/nios2/mm/fault.c b/arch/nios2/mm/fault.c
index 15a0bb5fc06d97..34429d5a0ccde6 100644
--- a/arch/nios2/mm/fault.c
+++ b/arch/nios2/mm/fault.c
@@ -135,6 +135,8 @@ survive:
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM)
goto out_of_memory;
+ else if (fault & VM_FAULT_SIGSEGV)
+ goto bad_area;
else if (fault & VM_FAULT_SIGBUS)
goto do_sigbus;
BUG();
diff --git a/arch/openrisc/mm/fault.c b/arch/openrisc/mm/fault.c
index 0703acf7d32768..230ac20ae7944f 100644
--- a/arch/openrisc/mm/fault.c
+++ b/arch/openrisc/mm/fault.c
@@ -171,6 +171,8 @@ good_area:
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM)
goto out_of_memory;
+ else if (fault & VM_FAULT_SIGSEGV)
+ goto bad_area;
else if (fault & VM_FAULT_SIGBUS)
goto do_sigbus;
BUG();
diff --git a/arch/parisc/mm/fault.c b/arch/parisc/mm/fault.c
index 3ca9c1131cfe0d..e5120e653240c4 100644
--- a/arch/parisc/mm/fault.c
+++ b/arch/parisc/mm/fault.c
@@ -256,6 +256,8 @@ good_area:
*/
if (fault & VM_FAULT_OOM)
goto out_of_memory;
+ else if (fault & VM_FAULT_SIGSEGV)
+ goto bad_area;
else if (fault & VM_FAULT_SIGBUS)
goto bad_area;
BUG();
diff --git a/arch/powerpc/mm/copro_fault.c b/arch/powerpc/mm/copro_fault.c
index 5a236f082c7838..1b5305d4bdabe9 100644
--- a/arch/powerpc/mm/copro_fault.c
+++ b/arch/powerpc/mm/copro_fault.c
@@ -76,7 +76,7 @@ int copro_handle_mm_fault(struct mm_struct *mm, unsigned long ea,
if (*flt & VM_FAULT_OOM) {
ret = -ENOMEM;
goto out_unlock;
- } else if (*flt & VM_FAULT_SIGBUS) {
+ } else if (*flt & (VM_FAULT_SIGBUS | VM_FAULT_SIGSEGV)) {
ret = -EFAULT;
goto out_unlock;
}
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index eb79907f34fac2..6154b0a2b06331 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -437,6 +437,8 @@ good_area:
*/
fault = handle_mm_fault(mm, vma, address, flags);
if (unlikely(fault & (VM_FAULT_RETRY|VM_FAULT_ERROR))) {
+ if (fault & VM_FAULT_SIGSEGV)
+ goto bad_area;
rc = mm_fault_error(regs, address, fault);
if (rc >= MM_FAULT_RETURN)
goto bail;
diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index 811937bb90be69..9065d5aa3932dd 100644
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -374,6 +374,12 @@ static noinline void do_fault_error(struct pt_regs *regs, int fault)
do_no_context(regs);
else
pagefault_out_of_memory();
+ } else if (fault & VM_FAULT_SIGSEGV) {
+ /* Kernel mode? Handle exceptions or die */
+ if (!user_mode(regs))
+ do_no_context(regs);
+ else
+ do_sigsegv(regs, SEGV_MAPERR);
} else if (fault & VM_FAULT_SIGBUS) {
/* Kernel mode? Handle exceptions or die */
if (!user_mode(regs))
diff --git a/arch/score/mm/fault.c b/arch/score/mm/fault.c
index 52238983527d60..6860beb2a280d0 100644
--- a/arch/score/mm/fault.c
+++ b/arch/score/mm/fault.c
@@ -114,6 +114,8 @@ good_area:
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM)
goto out_of_memory;
+ else if (fault & VM_FAULT_SIGSEGV)
+ goto bad_area;
else if (fault & VM_FAULT_SIGBUS)
goto do_sigbus;
BUG();
diff --git a/arch/sh/mm/fault.c b/arch/sh/mm/fault.c
index 541dc610150888..a58fec9b55e016 100644
--- a/arch/sh/mm/fault.c
+++ b/arch/sh/mm/fault.c
@@ -353,6 +353,8 @@ mm_fault_error(struct pt_regs *regs, unsigned long error_code,
} else {
if (fault & VM_FAULT_SIGBUS)
do_sigbus(regs, error_code, address);
+ else if (fault & VM_FAULT_SIGSEGV)
+ bad_area(regs, error_code, address);
else
BUG();
}
diff --git a/arch/sparc/mm/fault_32.c b/arch/sparc/mm/fault_32.c
index 908e8c17c902be..70d817154fe8bf 100644
--- a/arch/sparc/mm/fault_32.c
+++ b/arch/sparc/mm/fault_32.c
@@ -249,6 +249,8 @@ good_area:
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM)
goto out_of_memory;
+ else if (fault & VM_FAULT_SIGSEGV)
+ goto bad_area;
else if (fault & VM_FAULT_SIGBUS)
goto do_sigbus;
BUG();
diff --git a/arch/sparc/mm/fault_64.c b/arch/sparc/mm/fault_64.c
index 18fcd716709592..4798232494294a 100644
--- a/arch/sparc/mm/fault_64.c
+++ b/arch/sparc/mm/fault_64.c
@@ -446,6 +446,8 @@ good_area:
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM)
goto out_of_memory;
+ else if (fault & VM_FAULT_SIGSEGV)
+ goto bad_area;
else if (fault & VM_FAULT_SIGBUS)
goto do_sigbus;
BUG();
diff --git a/arch/tile/mm/fault.c b/arch/tile/mm/fault.c
index 565e25a9833420..0f61a73534e6d7 100644
--- a/arch/tile/mm/fault.c
+++ b/arch/tile/mm/fault.c
@@ -442,6 +442,8 @@ good_area:
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM)
goto out_of_memory;
+ else if (fault & VM_FAULT_SIGSEGV)
+ goto bad_area;
else if (fault & VM_FAULT_SIGBUS)
goto do_sigbus;
BUG();
diff --git a/arch/um/kernel/trap.c b/arch/um/kernel/trap.c
index 5678c3571e7cb4..209617302df89e 100644
--- a/arch/um/kernel/trap.c
+++ b/arch/um/kernel/trap.c
@@ -80,6 +80,8 @@ good_area:
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM) {
goto out_of_memory;
+ } else if (fault & VM_FAULT_SIGSEGV) {
+ goto out;
} else if (fault & VM_FAULT_SIGBUS) {
err = -EACCES;
goto out;
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 38dcec403b46ae..e3ff27a5b6348f 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -898,6 +898,8 @@ mm_fault_error(struct pt_regs *regs, unsigned long error_code,
if (fault & (VM_FAULT_SIGBUS|VM_FAULT_HWPOISON|
VM_FAULT_HWPOISON_LARGE))
do_sigbus(regs, error_code, address, fault);
+ else if (fault & VM_FAULT_SIGSEGV)
+ bad_area_nosemaphore(regs, error_code, address);
else
BUG();
}
diff --git a/arch/xtensa/mm/fault.c b/arch/xtensa/mm/fault.c
index b57c4f91f487ef..9e3571a6535c3b 100644
--- a/arch/xtensa/mm/fault.c
+++ b/arch/xtensa/mm/fault.c
@@ -117,6 +117,8 @@ good_area:
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM)
goto out_of_memory;
+ else if (fault & VM_FAULT_SIGSEGV)
+ goto bad_area;
else if (fault & VM_FAULT_SIGBUS)
goto do_sigbus;
BUG();
diff --git a/drivers/staging/lustre/lustre/llite/vvp_io.c b/drivers/staging/lustre/lustre/llite/vvp_io.c
index 930f6010203e96..65d610abe06e53 100644
--- a/drivers/staging/lustre/lustre/llite/vvp_io.c
+++ b/drivers/staging/lustre/lustre/llite/vvp_io.c
@@ -632,7 +632,7 @@ static int vvp_io_kernel_fault(struct vvp_fault_io *cfio)
return 0;
}
- if (cfio->fault.ft_flags & VM_FAULT_SIGBUS) {
+ if (cfio->fault.ft_flags & (VM_FAULT_SIGBUS | VM_FAULT_SIGSEGV)) {
CDEBUG(D_PAGE, "got addr %p - SIGBUS\n", vmf->virtual_address);
return -EFAULT;
}
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 80fc92a49649cf..dd5ea3016fc4e8 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1070,6 +1070,7 @@ static inline int page_mapped(struct page *page)
#define VM_FAULT_WRITE 0x0008 /* Special case for get_user_pages */
#define VM_FAULT_HWPOISON 0x0010 /* Hit poisoned small page */
#define VM_FAULT_HWPOISON_LARGE 0x0020 /* Hit poisoned large page. Index encoded in upper bits */
+#define VM_FAULT_SIGSEGV 0x0040
#define VM_FAULT_NOPAGE 0x0100 /* ->fault installed the pte, not return page */
#define VM_FAULT_LOCKED 0x0200 /* ->fault locked the returned page */
@@ -1078,8 +1079,9 @@ static inline int page_mapped(struct page *page)
#define VM_FAULT_HWPOISON_LARGE_MASK 0xf000 /* encodes hpage index for large hwpoison */
-#define VM_FAULT_ERROR (VM_FAULT_OOM | VM_FAULT_SIGBUS | VM_FAULT_HWPOISON | \
- VM_FAULT_FALLBACK | VM_FAULT_HWPOISON_LARGE)
+#define VM_FAULT_ERROR (VM_FAULT_OOM | VM_FAULT_SIGBUS | VM_FAULT_SIGSEGV | \
+ VM_FAULT_HWPOISON | VM_FAULT_HWPOISON_LARGE | \
+ VM_FAULT_FALLBACK)
/* Encode hstate index for a hwpoisoned large page */
#define VM_FAULT_SET_HINDEX(x) ((x) << 12)
diff --git a/mm/gup.c b/mm/gup.c
index a900759cc8075f..8dd50ce6326fd5 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -296,7 +296,7 @@ static int faultin_page(struct task_struct *tsk, struct vm_area_struct *vma,
return -ENOMEM;
if (ret & (VM_FAULT_HWPOISON | VM_FAULT_HWPOISON_LARGE))
return *flags & FOLL_HWPOISON ? -EHWPOISON : -EFAULT;
- if (ret & VM_FAULT_SIGBUS)
+ if (ret & (VM_FAULT_SIGBUS | VM_FAULT_SIGSEGV))
return -EFAULT;
BUG();
}
@@ -571,7 +571,7 @@ int fixup_user_fault(struct task_struct *tsk, struct mm_struct *mm,
return -ENOMEM;
if (ret & (VM_FAULT_HWPOISON | VM_FAULT_HWPOISON_LARGE))
return -EHWPOISON;
- if (ret & VM_FAULT_SIGBUS)
+ if (ret & (VM_FAULT_SIGBUS | VM_FAULT_SIGSEGV))
return -EFAULT;
BUG();
}
diff --git a/mm/ksm.c b/mm/ksm.c
index d247efab5073ab..15647fb0394fab 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -376,7 +376,7 @@ static int break_ksm(struct vm_area_struct *vma, unsigned long addr)
else
ret = VM_FAULT_WRITE;
put_page(page);
- } while (!(ret & (VM_FAULT_WRITE | VM_FAULT_SIGBUS | VM_FAULT_OOM)));
+ } while (!(ret & (VM_FAULT_WRITE | VM_FAULT_SIGBUS | VM_FAULT_SIGSEGV | VM_FAULT_OOM)));
/*
* We must loop because handle_mm_fault() may back out if there's
* any difficulty e.g. if pte accessed bit gets updated concurrently.
--
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