[patch 3/7] arch: mm: pass userspace fault flag to generic fault handler

From: Johannes Weiner
Date: Sat Aug 03 2013 - 13:01:37 EST

Unlike global OOM handling, memory cgroup code will invoke the OOM
killer in any OOM situation because it has no way of telling faults
occuring in kernel context - which could be handled more gracefully -
from user-triggered faults.

Pass a flag that identifies faults originating in user space from the
architecture-specific fault handlers to generic code so that memcg OOM
handling can be improved.

Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Reviewed-by: Michal Hocko <mhocko@xxxxxxx>
---
arch/alpha/mm/fault.c | 7 ++++---
arch/arc/mm/fault.c | 6 ++++--
arch/arm/mm/fault.c | 9 ++++++---
arch/arm64/mm/fault.c | 9 ++++++---
arch/avr32/mm/fault.c | 2 ++
arch/cris/mm/fault.c | 6 ++++--
arch/frv/mm/fault.c | 10 ++++++----
arch/hexagon/mm/vm_fault.c | 6 ++++--
arch/ia64/mm/fault.c | 6 ++++--
arch/m32r/mm/fault.c | 10 ++++++----
arch/m68k/mm/fault.c | 2 ++
arch/metag/mm/fault.c | 6 ++++--
arch/microblaze/mm/fault.c | 7 +++++--
arch/mips/mm/fault.c | 6 ++++--
arch/mn10300/mm/fault.c | 2 ++
arch/openrisc/mm/fault.c | 1 +
arch/parisc/mm/fault.c | 7 +++++--
arch/powerpc/mm/fault.c | 7 ++++---
arch/s390/mm/fault.c | 2 ++
arch/score/mm/fault.c | 7 ++++++-
arch/sh/mm/fault.c | 9 ++++++---
arch/sparc/mm/fault_32.c | 12 +++++++++---
arch/sparc/mm/fault_64.c | 8 +++++---
arch/tile/mm/fault.c | 7 +++++--
arch/um/kernel/trap.c | 20 ++++++++++++--------
arch/unicore32/mm/fault.c | 8 ++++++--
arch/x86/mm/fault.c | 8 +++++---
arch/xtensa/mm/fault.c | 2 ++
include/linux/mm.h | 1 +
29 files changed, 132 insertions(+), 61 deletions(-)

diff --git a/arch/alpha/mm/fault.c b/arch/alpha/mm/fault.c
index 0c4132d..98838a0 100644
--- a/arch/alpha/mm/fault.c
+++ b/arch/alpha/mm/fault.c
@@ -89,8 +89,7 @@ do_page_fault(unsigned long address, unsigned long mmcsr,
const struct exception_table_entry *fixup;
int fault, si_code = SEGV_MAPERR;
siginfo_t info;
- unsigned int flags = (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
- (cause > 0 ? FAULT_FLAG_WRITE : 0));
+ unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;

/* As of EV6, a load into $31/$f31 is a prefetch, and never faults
(or is suppressed by the PALcode). Support that for older CPUs
@@ -115,7 +114,8 @@ do_page_fault(unsigned long address, unsigned long mmcsr,
if (address >= TASK_SIZE)
goto vmalloc_fault;
#endif
-
+ if (user_mode(regs))
+ flags |= FAULT_FLAG_USER;
retry:
down_read(&mm->mmap_sem);
vma = find_vma(mm, address);
@@ -142,6 +142,7 @@ retry:
} else {
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
+ flags |= FAULT_FLAG_WRITE;
}

/* If for any reason at all we couldn't handle the fault,
diff --git a/arch/arc/mm/fault.c b/arch/arc/mm/fault.c
index 6b0bb41..d63f3de 100644
--- a/arch/arc/mm/fault.c
+++ b/arch/arc/mm/fault.c
@@ -60,8 +60,7 @@ void do_page_fault(struct pt_regs *regs, unsigned long address)
siginfo_t info;
int fault, ret;
int write = regs->ecr_cause & ECR_C_PROTV_STORE; /* ST/EX */
- unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
- (write ? FAULT_FLAG_WRITE : 0);
+ unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;

/*
* We fault-in kernel-space virtual memory on-demand. The
@@ -89,6 +88,8 @@ void do_page_fault(struct pt_regs *regs, unsigned long address)
if (in_atomic() || !mm)
goto no_context;

+ if (user_mode(regs))
+ flags |= FAULT_FLAG_USER;
retry:
down_read(&mm->mmap_sem);
vma = find_vma(mm, address);
@@ -117,6 +118,7 @@ good_area:
if (write) {
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
+ flags |= FAULT_FLAG_WRITE;
} else {
if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
goto bad_area;
diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
index 217bcbf..eb8830a 100644
--- a/arch/arm/mm/fault.c
+++ b/arch/arm/mm/fault.c
@@ -261,9 +261,7 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
struct task_struct *tsk;
struct mm_struct *mm;
int fault, sig, code;
- int write = fsr & FSR_WRITE;
- unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
- (write ? FAULT_FLAG_WRITE : 0);
+ unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;

if (notify_page_fault(regs, fsr))
return 0;
@@ -282,6 +280,11 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
if (in_atomic() || !mm)
goto no_context;

+ if (user_mode(regs))
+ flags |= FAULT_FLAG_USER;
+ if (fsr & FSR_WRITE)
+ flags |= FAULT_FLAG_WRITE;
+
/*
* As per x86, we may deadlock here. However, since the kernel only
* validly references user space from well defined areas of the code,
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index dab1cfd..12205b4 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -208,9 +208,7 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
struct task_struct *tsk;
struct mm_struct *mm;
int fault, sig, code;
- bool write = (esr & ESR_WRITE) && !(esr & ESR_CM);
- unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
- (write ? FAULT_FLAG_WRITE : 0);
+ unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;

tsk = current;
mm = tsk->mm;
@@ -226,6 +224,11 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
if (in_atomic() || !mm)
goto no_context;

+ if (user_mode(regs))
+ flags |= FAULT_FLAG_USER;
+ if ((esr & ESR_WRITE) && !(esr & ESR_CM))
+ flags |= FAULT_FLAG_WRITE;
+
/*
* As per x86, we may deadlock here. However, since the kernel only
* validly references user space from well defined areas of the code,
diff --git a/arch/avr32/mm/fault.c b/arch/avr32/mm/fault.c
index 2ca27b0..0eca933 100644
--- a/arch/avr32/mm/fault.c
+++ b/arch/avr32/mm/fault.c
@@ -86,6 +86,8 @@ asmlinkage void do_page_fault(unsigned long ecr, struct pt_regs *regs)

local_irq_enable();

+ if (user_mode(regs))
+ flags |= FAULT_FLAG_USER;
retry:
down_read(&mm->mmap_sem);

diff --git a/arch/cris/mm/fault.c b/arch/cris/mm/fault.c
index 73312ab..1790f22 100644
--- a/arch/cris/mm/fault.c
+++ b/arch/cris/mm/fault.c
@@ -58,8 +58,7 @@ do_page_fault(unsigned long address, struct pt_regs *regs,
struct vm_area_struct * vma;
siginfo_t info;
int fault;
- unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
- ((writeaccess & 1) ? FAULT_FLAG_WRITE : 0);
+ unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;

D(printk(KERN_DEBUG
"Page fault for %lX on %X at %lX, prot %d write %d\n",
@@ -117,6 +116,8 @@ do_page_fault(unsigned long address, struct pt_regs *regs,
if (in_atomic() || !mm)
goto no_context;

+ if (user_mode(regs))
+ flags |= FAULT_FLAG_USER;
retry:
down_read(&mm->mmap_sem);
vma = find_vma(mm, address);
@@ -155,6 +156,7 @@ retry:
} else if (writeaccess == 1) {
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
+ flags |= FAULT_FLAG_WRITE;
} else {
if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
goto bad_area;
diff --git a/arch/frv/mm/fault.c b/arch/frv/mm/fault.c
index 331c1e2..9a66372 100644
--- a/arch/frv/mm/fault.c
+++ b/arch/frv/mm/fault.c
@@ -34,11 +34,11 @@ asmlinkage void do_page_fault(int datammu, unsigned long esr0, unsigned long ear
struct vm_area_struct *vma;
struct mm_struct *mm;
unsigned long _pme, lrai, lrad, fixup;
+ unsigned long flags = 0;
siginfo_t info;
pgd_t *pge;
pud_t *pue;
pte_t *pte;
- int write;
int fault;

#if 0
@@ -81,6 +81,9 @@ asmlinkage void do_page_fault(int datammu, unsigned long esr0, unsigned long ear
if (in_atomic() || !mm)
goto no_context;

+ if (user_mode(__frame))
+ flags |= FAULT_FLAG_USER;
+
down_read(&mm->mmap_sem);

vma = find_vma(mm, ear0);
@@ -129,7 +132,6 @@ asmlinkage void do_page_fault(int datammu, unsigned long esr0, unsigned long ear
*/
good_area:
info.si_code = SEGV_ACCERR;
- write = 0;
switch (esr0 & ESR0_ATXC) {
default:
/* handle write to write protected page */
@@ -140,7 +142,7 @@ asmlinkage void do_page_fault(int datammu, unsigned long esr0, unsigned long ear
#endif
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
- write = 1;
+ flags |= FAULT_FLAG_WRITE;
break;

/* handle read from protected page */
@@ -162,7 +164,7 @@ asmlinkage void do_page_fault(int datammu, unsigned long esr0, unsigned long ear
* make sure we exit gracefully rather than endlessly redo
* the fault.
*/
- fault = handle_mm_fault(mm, vma, ear0, write ? FAULT_FLAG_WRITE : 0);
+ fault = handle_mm_fault(mm, vma, ear0, flags);
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM)
goto out_of_memory;
diff --git a/arch/hexagon/mm/vm_fault.c b/arch/hexagon/mm/vm_fault.c
index 1bd276d..8704c93 100644
--- a/arch/hexagon/mm/vm_fault.c
+++ b/arch/hexagon/mm/vm_fault.c
@@ -53,8 +53,7 @@ void do_page_fault(unsigned long address, long cause, struct pt_regs *regs)
int si_code = SEGV_MAPERR;
int fault;
const struct exception_table_entry *fixup;
- unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
- (cause > 0 ? FAULT_FLAG_WRITE : 0);
+ unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;

/*
* If we're in an interrupt or have no user context,
@@ -65,6 +64,8 @@ void do_page_fault(unsigned long address, long cause, struct pt_regs *regs)

local_irq_enable();

+ if (user_mode(regs))
+ flags |= FAULT_FLAG_USER;
retry:
down_read(&mm->mmap_sem);
vma = find_vma(mm, address);
@@ -96,6 +97,7 @@ good_area:
case FLT_STORE:
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
+ flags |= FAULT_FLAG_WRITE;
break;
}

diff --git a/arch/ia64/mm/fault.c b/arch/ia64/mm/fault.c
index 6cf0341..7225dad 100644
--- a/arch/ia64/mm/fault.c
+++ b/arch/ia64/mm/fault.c
@@ -90,8 +90,6 @@ ia64_do_page_fault (unsigned long address, unsigned long isr, struct pt_regs *re
mask = ((((isr >> IA64_ISR_X_BIT) & 1UL) << VM_EXEC_BIT)
| (((isr >> IA64_ISR_W_BIT) & 1UL) << VM_WRITE_BIT));

- flags |= ((mask & VM_WRITE) ? FAULT_FLAG_WRITE : 0);
-
/* mmap_sem is performance critical.... */
prefetchw(&mm->mmap_sem);

@@ -119,6 +117,10 @@ ia64_do_page_fault (unsigned long address, unsigned long isr, struct pt_regs *re
if (notify_page_fault(regs, TRAP_BRKPT))
return;

+ if (user_mode(regs))
+ flags |= FAULT_FLAG_USER;
+ if (mask & VM_WRITE)
+ flags |= FAULT_FLAG_WRITE;
retry:
down_read(&mm->mmap_sem);

diff --git a/arch/m32r/mm/fault.c b/arch/m32r/mm/fault.c
index 3cdfa9c..e9c6a80 100644
--- a/arch/m32r/mm/fault.c
+++ b/arch/m32r/mm/fault.c
@@ -78,7 +78,7 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long error_code,
struct mm_struct *mm;
struct vm_area_struct * vma;
unsigned long page, addr;
- int write;
+ unsigned long flags = 0;
int fault;
siginfo_t info;

@@ -117,6 +117,9 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long error_code,
if (in_atomic() || !mm)
goto bad_area_nosemaphore;

+ if (error_code & ACE_USERMODE)
+ flags |= FAULT_FLAG_USER;
+
/* When running in the kernel we expect faults to occur only to
* addresses in user space. All other faults represent errors in the
* kernel and should generate an OOPS. Unfortunately, in the case of an
@@ -166,14 +169,13 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long error_code,
*/
good_area:
info.si_code = SEGV_ACCERR;
- write = 0;
switch (error_code & (ACE_WRITE|ACE_PROTECTION)) {
default: /* 3: write, present */
/* fall through */
case ACE_WRITE: /* write, not present */
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
- write++;
+ flags |= FAULT_FLAG_WRITE;
break;
case ACE_PROTECTION: /* read, present */
case 0: /* read, not present */
@@ -194,7 +196,7 @@ good_area:
*/
addr = (address & PAGE_MASK);
set_thread_fault_code(error_code);
- fault = handle_mm_fault(mm, vma, addr, write ? FAULT_FLAG_WRITE : 0);
+ fault = handle_mm_fault(mm, vma, addr, flags);
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM)
goto out_of_memory;
diff --git a/arch/m68k/mm/fault.c b/arch/m68k/mm/fault.c
index a563727..eb1d61f 100644
--- a/arch/m68k/mm/fault.c
+++ b/arch/m68k/mm/fault.c
@@ -88,6 +88,8 @@ int do_page_fault(struct pt_regs *regs, unsigned long address,
if (in_atomic() || !mm)
goto no_context;

+ if (user_mode(regs))
+ flags |= FAULT_FLAG_USER;
retry:
down_read(&mm->mmap_sem);

diff --git a/arch/metag/mm/fault.c b/arch/metag/mm/fault.c
index 8fddf46..332680e 100644
--- a/arch/metag/mm/fault.c
+++ b/arch/metag/mm/fault.c
@@ -53,8 +53,7 @@ int do_page_fault(struct pt_regs *regs, unsigned long address,
struct vm_area_struct *vma, *prev_vma;
siginfo_t info;
int fault;
- unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
- (write_access ? FAULT_FLAG_WRITE : 0);
+ unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;

tsk = current;

@@ -109,6 +108,8 @@ int do_page_fault(struct pt_regs *regs, unsigned long address,
if (in_atomic() || !mm)
goto no_context;

+ if (user_mode(regs))
+ flags |= FAULT_FLAG_USER;
retry:
down_read(&mm->mmap_sem);

@@ -121,6 +122,7 @@ good_area:
if (write_access) {
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
+ flags |= FAULT_FLAG_WRITE;
} else {
if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
goto bad_area;
diff --git a/arch/microblaze/mm/fault.c b/arch/microblaze/mm/fault.c
index 731f739..fa4cf52 100644
--- a/arch/microblaze/mm/fault.c
+++ b/arch/microblaze/mm/fault.c
@@ -92,8 +92,7 @@ void do_page_fault(struct pt_regs *regs, unsigned long address,
int code = SEGV_MAPERR;
int is_write = error_code & ESR_S;
int fault;
- unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
- (is_write ? FAULT_FLAG_WRITE : 0);
+ unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;

regs->ear = address;
regs->esr = error_code;
@@ -121,6 +120,9 @@ void do_page_fault(struct pt_regs *regs, unsigned long address,
die("Weird page fault", regs, SIGSEGV);
}

+ if (user_mode(regs))
+ flags |= FAULT_FLAG_USER;
+
/* When running in the kernel we expect faults to occur only to
* addresses in user space. All other faults represent errors in the
* kernel and should generate an OOPS. Unfortunately, in the case of an
@@ -199,6 +201,7 @@ good_area:
if (unlikely(is_write)) {
if (unlikely(!(vma->vm_flags & VM_WRITE)))
goto bad_area;
+ flags |= FAULT_FLAG_WRITE;
/* a read */
} else {
/* protection fault */
diff --git a/arch/mips/mm/fault.c b/arch/mips/mm/fault.c
index 94d3a31..becc42b 100644
--- a/arch/mips/mm/fault.c
+++ b/arch/mips/mm/fault.c
@@ -42,8 +42,7 @@ static void __kprobes __do_page_fault(struct pt_regs *regs, unsigned long write,
const int field = sizeof(unsigned long) * 2;
siginfo_t info;
int fault;
- unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
- (write ? FAULT_FLAG_WRITE : 0);
+ unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;

#if 0
printk("Cpu%d[%s:%d:%0*lx:%ld:%0*lx]\n", raw_smp_processor_id(),
@@ -93,6 +92,8 @@ static void __kprobes __do_page_fault(struct pt_regs *regs, unsigned long write,
if (in_atomic() || !mm)
goto bad_area_nosemaphore;

+ if (user_mode(regs))
+ flags |= FAULT_FLAG_USER;
retry:
down_read(&mm->mmap_sem);
vma = find_vma(mm, address);
@@ -114,6 +115,7 @@ good_area:
if (write) {
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
+ flags |= FAULT_FLAG_WRITE;
} else {
if (cpu_has_rixi) {
if (address == regs->cp0_epc && !(vma->vm_flags & VM_EXEC)) {
diff --git a/arch/mn10300/mm/fault.c b/arch/mn10300/mm/fault.c
index 8a2e6de..3516cbd 100644
--- a/arch/mn10300/mm/fault.c
+++ b/arch/mn10300/mm/fault.c
@@ -171,6 +171,8 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long fault_code,
if (in_atomic() || !mm)
goto no_context;

+ if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_USR)
+ flags |= FAULT_FLAG_USER;
retry:
down_read(&mm->mmap_sem);

diff --git a/arch/openrisc/mm/fault.c b/arch/openrisc/mm/fault.c
index 4a41f84..0703acf 100644
--- a/arch/openrisc/mm/fault.c
+++ b/arch/openrisc/mm/fault.c
@@ -86,6 +86,7 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long address,
if (user_mode(regs)) {
/* Exception was in userspace: reenable interrupts */
local_irq_enable();
+ flags |= FAULT_FLAG_USER;
} else {
/* If exception was in a syscall, then IRQ's may have
* been enabled or disabled. If they were enabled,
diff --git a/arch/parisc/mm/fault.c b/arch/parisc/mm/fault.c
index f247a34..d10d27a 100644
--- a/arch/parisc/mm/fault.c
+++ b/arch/parisc/mm/fault.c
@@ -180,6 +180,10 @@ void do_page_fault(struct pt_regs *regs, unsigned long code,
if (in_atomic() || !mm)
goto no_context;

+ if (user_mode(regs))
+ flags |= FAULT_FLAG_USER;
+ if (acc_type & VM_WRITE)
+ flags |= FAULT_FLAG_WRITE;
retry:
down_read(&mm->mmap_sem);
vma = find_vma_prev(mm, address, &prev_vma);
@@ -203,8 +207,7 @@ good_area:
* fault.
*/

- fault = handle_mm_fault(mm, vma, address,
- flags | ((acc_type & VM_WRITE) ? FAULT_FLAG_WRITE : 0));
+ fault = handle_mm_fault(mm, vma, address, flags);

if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
return;
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 8726779..d9196c9 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -223,9 +223,6 @@ int __kprobes do_page_fault(struct pt_regs *regs, unsigned long address,
is_write = error_code & ESR_DST;
#endif /* CONFIG_4xx || CONFIG_BOOKE */

- if (is_write)
- flags |= FAULT_FLAG_WRITE;
-
#ifdef CONFIG_PPC_ICSWX
/*
* we need to do this early because this "data storage
@@ -280,6 +277,9 @@ int __kprobes do_page_fault(struct pt_regs *regs, unsigned long address,

perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);

+ if (user_mode(regs))
+ flags |= FAULT_FLAG_USER;
+
/* When running in the kernel we expect faults to occur only to
* addresses in user space. All other faults represent errors in the
* kernel and should generate an OOPS. Unfortunately, in the case of an
@@ -408,6 +408,7 @@ good_area:
} else if (is_write) {
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
+ flags |= FAULT_FLAG_WRITE;
/* a read */
} else {
/* protection fault */
diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index f00aefb..35b81d6 100644
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -302,6 +302,8 @@ static inline int do_exception(struct pt_regs *regs, int access)
address = trans_exc_code & __FAIL_ADDR_MASK;
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
+ if (user_mode(regs))
+ flags |= FAULT_FLAG_USER;
if (access == VM_WRITE || (trans_exc_code & store_indication) == 0x400)
flags |= FAULT_FLAG_WRITE;
down_read(&mm->mmap_sem);
diff --git a/arch/score/mm/fault.c b/arch/score/mm/fault.c
index 4b71a62..52238983 100644
--- a/arch/score/mm/fault.c
+++ b/arch/score/mm/fault.c
@@ -47,6 +47,7 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long write,
struct task_struct *tsk = current;
struct mm_struct *mm = tsk->mm;
const int field = sizeof(unsigned long) * 2;
+ unsigned long flags = 0;
siginfo_t info;
int fault;

@@ -75,6 +76,9 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long write,
if (in_atomic() || !mm)
goto bad_area_nosemaphore;

+ if (user_mode(regs))
+ flags |= FAULT_FLAG_USER;
+
down_read(&mm->mmap_sem);
vma = find_vma(mm, address);
if (!vma)
@@ -95,6 +99,7 @@ good_area:
if (write) {
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
+ flags |= FAULT_FLAG_WRITE;
} else {
if (!(vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC)))
goto bad_area;
@@ -105,7 +110,7 @@ good_area:
* make sure we exit gracefully rather than endlessly redo
* the fault.
*/
- fault = handle_mm_fault(mm, vma, address, write);
+ fault = handle_mm_fault(mm, vma, address, flags);
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM)
goto out_of_memory;
diff --git a/arch/sh/mm/fault.c b/arch/sh/mm/fault.c
index 1f49c28..541dc61 100644
--- a/arch/sh/mm/fault.c
+++ b/arch/sh/mm/fault.c
@@ -400,9 +400,7 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
struct mm_struct *mm;
struct vm_area_struct * vma;
int fault;
- int write = error_code & FAULT_CODE_WRITE;
- unsigned int flags = (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
- (write ? FAULT_FLAG_WRITE : 0));
+ unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;

tsk = current;
mm = tsk->mm;
@@ -476,6 +474,11 @@ good_area:

set_thread_fault_code(error_code);

+ if (user_mode(regs))
+ flags |= FAULT_FLAG_USER;
+ if (error_code & FAULT_CODE_WRITE)
+ flags |= FAULT_FLAG_WRITE;
+
/*
* If for any reason at all we couldn't handle the fault,
* make sure we exit gracefully rather than endlessly redo
diff --git a/arch/sparc/mm/fault_32.c b/arch/sparc/mm/fault_32.c
index e98bfda..59dbd46 100644
--- a/arch/sparc/mm/fault_32.c
+++ b/arch/sparc/mm/fault_32.c
@@ -177,8 +177,7 @@ asmlinkage void do_sparc_fault(struct pt_regs *regs, int text_fault, int write,
unsigned long g2;
int from_user = !(regs->psr & PSR_PS);
int fault, code;
- unsigned int flags = (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
- (write ? FAULT_FLAG_WRITE : 0));
+ unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;

if (text_fault)
address = regs->pc;
@@ -235,6 +234,11 @@ good_area:
goto bad_area;
}

+ if (from_user)
+ flags |= FAULT_FLAG_USER;
+ if (write)
+ flags |= FAULT_FLAG_WRITE;
+
/*
* If for any reason at all we couldn't handle the fault,
* make sure we exit gracefully rather than endlessly redo
@@ -383,6 +387,7 @@ static void force_user_fault(unsigned long address, int write)
struct vm_area_struct *vma;
struct task_struct *tsk = current;
struct mm_struct *mm = tsk->mm;
+ unsigned int flags = FAULT_FLAG_USER;
int code;

code = SEGV_MAPERR;
@@ -402,11 +407,12 @@ good_area:
if (write) {
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
+ flags |= FAULT_FLAG_WRITE;
} else {
if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
goto bad_area;
}
- switch (handle_mm_fault(mm, vma, address, write ? FAULT_FLAG_WRITE : 0)) {
+ switch (handle_mm_fault(mm, vma, address, flags)) {
case VM_FAULT_SIGBUS:
case VM_FAULT_OOM:
goto do_sigbus;
diff --git a/arch/sparc/mm/fault_64.c b/arch/sparc/mm/fault_64.c
index 5062ff3..c08b9bb 100644
--- a/arch/sparc/mm/fault_64.c
+++ b/arch/sparc/mm/fault_64.c
@@ -314,8 +314,9 @@ asmlinkage void __kprobes do_sparc64_fault(struct pt_regs *regs)
} else {
bad_kernel_pc(regs, address);
return;
- }
- }
+ }
+ } else
+ flags |= FAULT_FLAG_USER;

/*
* If we're in an interrupt or have no user
@@ -418,13 +419,14 @@ good_area:
vma->vm_file != NULL)
set_thread_fault_code(fault_code |
FAULT_CODE_BLKCOMMIT);
+
+ flags |= FAULT_FLAG_WRITE;
} else {
/* Allow reads even for write-only mappings */
if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
goto bad_area;
}

- flags |= ((fault_code & FAULT_CODE_WRITE) ? FAULT_FLAG_WRITE : 0);
fault = handle_mm_fault(mm, vma, address, flags);

if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
diff --git a/arch/tile/mm/fault.c b/arch/tile/mm/fault.c
index ac553ee..3ff289f 100644
--- a/arch/tile/mm/fault.c
+++ b/arch/tile/mm/fault.c
@@ -280,8 +280,7 @@ static int handle_page_fault(struct pt_regs *regs,
if (!is_page_fault)
write = 1;

- flags = (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
- (write ? FAULT_FLAG_WRITE : 0));
+ flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;

is_kernel_mode = (EX1_PL(regs->ex1) != USER_PL);

@@ -365,6 +364,9 @@ static int handle_page_fault(struct pt_regs *regs,
goto bad_area_nosemaphore;
}

+ if (!is_kernel_mode)
+ flags |= FAULT_FLAG_USER;
+
/*
* When running in the kernel we expect faults to occur only to
* addresses in user space. All other faults represent errors in the
@@ -425,6 +427,7 @@ good_area:
#endif
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
+ flags |= FAULT_FLAG_WRITE;
} else {
if (!is_page_fault || !(vma->vm_flags & VM_READ))
goto bad_area;
diff --git a/arch/um/kernel/trap.c b/arch/um/kernel/trap.c
index b2f5adf..5c3aef7 100644
--- a/arch/um/kernel/trap.c
+++ b/arch/um/kernel/trap.c
@@ -30,8 +30,7 @@ int handle_page_fault(unsigned long address, unsigned long ip,
pmd_t *pmd;
pte_t *pte;
int err = -EFAULT;
- unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
- (is_write ? FAULT_FLAG_WRITE : 0);
+ unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;

*code_out = SEGV_MAPERR;

@@ -42,6 +41,8 @@ int handle_page_fault(unsigned long address, unsigned long ip,
if (in_atomic())
goto out_nosemaphore;

+ if (is_user)
+ flags |= FAULT_FLAG_USER;
retry:
down_read(&mm->mmap_sem);
vma = find_vma(mm, address);
@@ -58,12 +59,15 @@ retry:

good_area:
*code_out = SEGV_ACCERR;
- if (is_write && !(vma->vm_flags & VM_WRITE))
- goto out;
-
- /* Don't require VM_READ|VM_EXEC for write faults! */
- if (!is_write && !(vma->vm_flags & (VM_READ | VM_EXEC)))
- goto out;
+ if (is_write) {
+ if (!(vma->vm_flags & VM_WRITE))
+ goto out;
+ flags |= FAULT_FLAG_WRITE;
+ } else {
+ /* Don't require VM_READ|VM_EXEC for write faults! */
+ if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
+ goto out;
+ }

do {
int fault;
diff --git a/arch/unicore32/mm/fault.c b/arch/unicore32/mm/fault.c
index 8ed3c45..0dc922d 100644
--- a/arch/unicore32/mm/fault.c
+++ b/arch/unicore32/mm/fault.c
@@ -209,8 +209,7 @@ static int do_pf(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
struct task_struct *tsk;
struct mm_struct *mm;
int fault, sig, code;
- unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
- ((!(fsr ^ 0x12)) ? FAULT_FLAG_WRITE : 0);
+ unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;

tsk = current;
mm = tsk->mm;
@@ -222,6 +221,11 @@ static int do_pf(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
if (in_atomic() || !mm)
goto no_context;

+ if (user_mode(regs))
+ flags |= FAULT_FLAG_USER;
+ if (!(fsr ^ 0x12))
+ flags |= FAULT_FLAG_WRITE;
+
/*
* As per x86, we may deadlock here. However, since the kernel only
* validly references user space from well defined areas of the code,
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 654be4a..6d77c38 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -1011,9 +1011,7 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code)
unsigned long address;
struct mm_struct *mm;
int fault;
- int write = error_code & PF_WRITE;
- unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
- (write ? FAULT_FLAG_WRITE : 0);
+ unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;

tsk = current;
mm = tsk->mm;
@@ -1083,6 +1081,7 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code)
if (user_mode_vm(regs)) {
local_irq_enable();
error_code |= PF_USER;
+ flags |= FAULT_FLAG_USER;
} else {
if (regs->flags & X86_EFLAGS_IF)
local_irq_enable();
@@ -1109,6 +1108,9 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code)
return;
}

+ if (error_code & PF_WRITE)
+ flags |= FAULT_FLAG_WRITE;
+
/*
* When running in the kernel we expect faults to occur only to
* addresses in user space. All other faults represent errors in
diff --git a/arch/xtensa/mm/fault.c b/arch/xtensa/mm/fault.c
index 4b7bc8d..70fa7bc 100644
--- a/arch/xtensa/mm/fault.c
+++ b/arch/xtensa/mm/fault.c
@@ -72,6 +72,8 @@ void do_page_fault(struct pt_regs *regs)
address, exccause, regs->pc, is_write? "w":"", is_exec? "x":"");
#endif

+ if (user_mode(regs))
+ flags |= FAULT_FLAG_USER;
retry:
down_read(&mm->mmap_sem);
vma = find_vma(mm, address);
diff --git a/include/linux/mm.h b/include/linux/mm.h
index d5c82dc..c51fc32 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -170,6 +170,7 @@ extern pgprot_t protection_map[16];
#define FAULT_FLAG_RETRY_NOWAIT 0x10 /* Don't drop mmap_sem and wait when retrying */
#define FAULT_FLAG_KILLABLE 0x20 /* The fault task is in SIGKILL killable region */
#define FAULT_FLAG_TRIED 0x40 /* second try */
+#define FAULT_FLAG_USER 0x80 /* The fault originated in userspace */

/*
* vm_fault is filled by the the pagefault handler and passed to the vma's
--
1.8.3.2

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