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.
Change-Id: Ib2cf8c19833e17d8d145e29141d68aaefd4dc233
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>
Git-commit: e0d407564b532d978b03ceccebd224a05d02f111
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
CRs-fixed: 561044
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>
diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index 1a65c31..7fa2fa5 100644
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -753,35 +753,32 @@
}
}
-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;
}