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MIPS: Call find_vma with the mmap_sem held 

Performing vma lookups without taking the mm->mmap_sem is asking
for trouble. While doing the search, the vma in question can be
modified or even removed before returning to the caller. Take the
lock (exclusively) in order to avoid races while iterating through
the vmacache and/or rbtree.

Updates two functions:
  - process_fpemu_return()
  - cteon_flush_cache_sigtramp()

Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>
Tested-by: Andreas Herrmann <andreas.herrmann@caviumnetworks.com>
Cc: linux-mips@linux-mips.org
Cc: akpm@linux-foundation.org
Cc: zeus@gnu.org
Cc: aswin@hp.com
Cc: davidlohr@hp.com
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
Patchwork: http://patchwork.linux-mips.org/patch/6811/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
hifive-unleashed-5.1
Davidlohr Bueso 2014-04-19 19:26:28 -07:00 committed by Ralf Baechle
parent 25198235c7
commit f7a89f1b8e
2 changed files with 4 additions and 0 deletions
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2
arch/mips/kernel/traps.c
View File

@ -712,10 +712,12 @@ int process_fpemu_return(int sig, void __user *fault_addr)
si.si_addr = fault_addr;
si.si_signo = sig;
if (sig == SIGSEGV) {
down_read(&current->mm->mmap_sem);
if (find_vma(current->mm, (unsigned long)fault_addr))
si.si_code = SEGV_ACCERR;
else
si.si_code = SEGV_MAPERR;
up_read(&current->mm->mmap_sem);
} else {
si.si_code = BUS_ADRERR;
}

2
arch/mips/mm/c-octeon.c
View File

@ -137,8 +137,10 @@ static void octeon_flush_cache_sigtramp(unsigned long addr)
{
struct vm_area_struct *vma;
down_read(&current->mm->mmap_sem);
vma = find_vma(current->mm, addr);
octeon_flush_icache_all_cores(vma);
up_read(&current->mm->mmap_sem);
}