From e0d407564b532d978b03ceccebd224a05d02f111 Mon Sep 17 00:00:00 2001
From: Russell King <rmk+kernel@arm.linux.org.uk>
Date: Sat, 3 Aug 2013 10:30:05 +0100
Subject: ARM: fix a cockup in 48be69a02 (ARM: move signal handlers into a
vdso-like page)
Unfortunately, I never committed the fix to a nasty oops which can
occur as a result of that commit:
------------[ cut here ]------------
kernel BUG at /home/olof/work/batch/include/linux/mm.h:414!
Internal error: Oops - BUG: 0 [#1] PREEMPT SMP ARM
Modules linked in:
CPU: 0 PID: 490 Comm: killall5 Not tainted 3.11.0-rc3-00288-gabe0308 #53
task: e90acac0 ti: e9be8000 task.ti: e9be8000
PC is at special_mapping_fault+0xa4/0xc4
LR is at __do_fault+0x68/0x48c
This doesn't show up unless you do quite a bit of testing; a simple
boot test does not do this, so all my nightly tests were passing fine.
The reason for this is that install_special_mapping() expects the
page array to stick around, and as this was only inserting one page
which was stored on the kernel stack, that's why this was blowing up.
Reported-by: Olof Johansson <olof@lixom.net>
Tested-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
---
arch/arm/kernel/process.c | 9 +++++----
arch/arm/kernel/signal.c | 41 +++++++++++++++++++----------------------
2 files changed, 24 insertions(+), 26 deletions(-)
(limited to 'arch/arm/kernel')
diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 1e6c33d01c0..d03b5bd889c 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -471,17 +471,18 @@ const char *arch_vma_name(struct vm_area_struct *vma)
"[sigpage]" : NULL;
}
+static struct page *signal_page;
extern struct page *get_signal_page(void);
int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
{
struct mm_struct *mm = current->mm;
- struct page *page;
unsigned long addr;
int ret;
- page = get_signal_page();
- if (!page)
+ if (!signal_page)
+ signal_page = get_signal_page();
+ if (!signal_page)
return -ENOMEM;
down_write(&mm->mmap_sem);
@@ -493,7 +494,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
ret = install_special_mapping(mm, addr, PAGE_SIZE,
VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
- &page);
+ &signal_page);
if (ret == 0)
mm->context.sigpage = addr;
diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index 0f17e06d51e..39e7105a9b7 100644
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -614,35 +614,32 @@ do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
return 0;
}
-static struct page *signal_page;
-
struct page *get_signal_page(void)
{
- if (!signal_page) {
- unsigned long ptr;
- unsigned offset;
- void *addr;
+ unsigned long ptr;
+ unsigned offset;
+ struct page *page;
+ void *addr;
- signal_page = alloc_pages(GFP_KERNEL, 0);
+ page = alloc_pages(GFP_KERNEL, 0);
- if (!signal_page)
- return NULL;
+ if (!page)
+ return NULL;
- addr = page_address(signal_page);
+ addr = page_address(page);
- /* Give the signal return code some randomness */
- offset = 0x200 + (get_random_int() & 0x7fc);
- signal_return_offset = offset;
+ /* Give the signal return code some randomness */
+ offset = 0x200 + (get_random_int() & 0x7fc);
+ signal_return_offset = offset;
- /*
- * Copy signal return handlers into the vector page, and
- * set sigreturn to be a pointer to these.
- */
- memcpy(addr + offset, sigreturn_codes, sizeof(sigreturn_codes));
+ /*
+ * Copy signal return handlers into the vector page, and
+ * set sigreturn to be a pointer to these.
+ */
+ memcpy(addr + offset, sigreturn_codes, sizeof(sigreturn_codes));
- ptr = (unsigned long)addr + offset;
- flush_icache_range(ptr, ptr + sizeof(sigreturn_codes));
- }
+ ptr = (unsigned long)addr + offset;
+ flush_icache_range(ptr, ptr + sizeof(sigreturn_codes));
- return signal_page;
+ return page;
}
--
cgit v1.2.3-18-g5258
From 8c0cc8a5d90bc7373a7a9e7f7a40eb41f51e03fc Mon Sep 17 00:00:00 2001
From: Russell King <rmk+kernel@arm.linux.org.uk>
Date: Sat, 3 Aug 2013 10:39:51 +0100
Subject: ARM: fix nommu builds with 48be69a02 (ARM: move signal handlers into
a vdso-like page)
Olof reports that noMMU builds error out with:
arch/arm/kernel/signal.c: In function 'setup_return':
arch/arm/kernel/signal.c:413:25: error: 'mm_context_t' has no member named 'sigpage'
This shows one of the evilnesses of IS_ENABLED(). Get rid of it here
and replace it with #ifdef's - and as no noMMU platform can make use
of sigpage, depend on CONIFG_MMU not CONFIG_ARM_MPU.
Reported-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
---
arch/arm/kernel/signal.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
(limited to 'arch/arm/kernel')
diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index 39e7105a9b7..ab330422527 100644
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -402,7 +402,8 @@ setup_return(struct pt_regs *regs, struct ksignal *ksig,
__put_user(sigreturn_codes[idx+1], rc+1))
return 1;
- if ((cpsr & MODE32_BIT) && !IS_ENABLED(CONFIG_ARM_MPU)) {
+#ifdef CONFIG_MMU
+ if (cpsr & MODE32_BIT) {
struct mm_struct *mm = current->mm;
/*
@@ -412,7 +413,9 @@ setup_return(struct pt_regs *regs, struct ksignal *ksig,
*/
retcode = mm->context.sigpage + signal_return_offset +
(idx << 2) + thumb;
- } else {
+ } else
+#endif
+ {
/*
* Ensure that the instruction cache sees
* the return code written onto the stack.
--
cgit v1.2.3-18-g5258