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Subject[tip:sched/core] sched: Add helper for task stack page overrun checking
Commit-ID:  a70857e46dd13e87ae06bf0e64cb6a2d4f436265
Gitweb: http://git.kernel.org/tip/a70857e46dd13e87ae06bf0e64cb6a2d4f436265
Author: Aaron Tomlin <atomlin@redhat.com>
AuthorDate: Fri, 12 Sep 2014 14:16:18 +0100
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Fri, 19 Sep 2014 12:35:23 +0200

sched: Add helper for task stack page overrun checking

This facility is used in a few places so let's introduce
a helper function to improve code readability.

Signed-off-by: Aaron Tomlin <atomlin@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: aneesh.kumar@linux.vnet.ibm.com
Cc: dzickus@redhat.com
Cc: bmr@redhat.com
Cc: jcastillo@redhat.com
Cc: oleg@redhat.com
Cc: riel@redhat.com
Cc: prarit@redhat.com
Cc: jgh@redhat.com
Cc: minchan@kernel.org
Cc: mpe@ellerman.id.au
Cc: tglx@linutronix.de
Cc: hannes@cmpxchg.org
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Seiji Aguchi <seiji.aguchi@hds.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/1410527779-8133-3-git-send-email-atomlin@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/powerpc/mm/fault.c | 4 +---
arch/x86/mm/fault.c | 4 +---
include/linux/sched.h | 2 ++
kernel/trace/trace_stack.c | 2 +-
4 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 35d0760c..99b2f27 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -507,7 +507,6 @@ bail:
void bad_page_fault(struct pt_regs *regs, unsigned long address, int sig)
{
const struct exception_table_entry *entry;
- unsigned long *stackend;

/* Are we prepared to handle this fault? */
if ((entry = search_exception_tables(regs->nip)) != NULL) {
@@ -536,8 +535,7 @@ void bad_page_fault(struct pt_regs *regs, unsigned long address, int sig)
printk(KERN_ALERT "Faulting instruction address: 0x%08lx\n",
regs->nip);

- stackend = end_of_stack(current);
- if (*stackend != STACK_END_MAGIC)
+ if (task_stack_end_corrupted(current))
printk(KERN_ALERT "Thread overran stack, or stack corrupted\n");

die("Kernel access of bad area", regs, sig);
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index bc23a70..6240bc7 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -648,7 +648,6 @@ no_context(struct pt_regs *regs, unsigned long error_code,
unsigned long address, int signal, int si_code)
{
struct task_struct *tsk = current;
- unsigned long *stackend;
unsigned long flags;
int sig;

@@ -708,8 +707,7 @@ no_context(struct pt_regs *regs, unsigned long error_code,

show_fault_oops(regs, error_code, address);

- stackend = end_of_stack(tsk);
- if (*stackend != STACK_END_MAGIC)
+ if (task_stack_end_corrupted(tsk))
printk(KERN_EMERG "Thread overran stack, or stack corrupted\n");

tsk->thread.cr2 = address;
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 118dca7..18f5262 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2617,6 +2617,8 @@ static inline unsigned long *end_of_stack(struct task_struct *p)
}

#endif
+#define task_stack_end_corrupted(task) \
+ (*(end_of_stack(task)) != STACK_END_MAGIC)

static inline int object_is_on_stack(void *obj)
{
diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c
index 1636e41..16eddb3 100644
--- a/kernel/trace/trace_stack.c
+++ b/kernel/trace/trace_stack.c
@@ -170,7 +170,7 @@ check_stack(unsigned long ip, unsigned long *stack)
i++;
}

- if (*end_of_stack(current) != STACK_END_MAGIC) {
+ if (task_stack_end_corrupted(current)) {
print_max_stack();
BUG();
}

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