Revision f43c27188a49111b58e9611afa2f0365b0b55625 authored by Lorenzo Pieralisi on 19 December 2014, 17:03:47 UTC, committed by Catalin Marinas on 23 December 2014, 16:38:50 UTC
On arm64 the TTBR0_EL1 register is set to either the reserved TTBR0 page tables on boot or to the active_mm mappings belonging to user space processes, it must never be set to swapper_pg_dir page tables mappings. When a CPU is booted its active_mm is set to init_mm even though its TTBR0_EL1 points at the reserved TTBR0 page mappings. This implies that when __cpu_suspend is triggered the active_mm can point at init_mm even if the current TTBR0_EL1 register contains the reserved TTBR0_EL1 mappings. Therefore, the mm save and restore executed in __cpu_suspend might turn out to be erroneous in that, if the current->active_mm corresponds to init_mm, on resume from low power it ends up restoring in the TTBR0_EL1 the init_mm mappings that are global and can cause speculation of TLB entries which end up being propagated to user space. This patch fixes the issue by checking the active_mm pointer before restoring the TTBR0 mappings. If the current active_mm == &init_mm, the code sets the TTBR0_EL1 to the reserved TTBR0 mapping instead of switching back to the active_mm, which is the expected behaviour corresponding to the TTBR0_EL1 settings when __cpu_suspend was entered. Fixes: 95322526ef62 ("arm64: kernel: cpu_{suspend/resume} implementation") Cc: <stable@vger.kernel.org> # 3.14+: 18ab7db Cc: <stable@vger.kernel.org> # 3.14+: 714f599 Cc: <stable@vger.kernel.org> # 3.14+: c3684fb Cc: <stable@vger.kernel.org> # 3.14+ Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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fadvise.c
/*
* mm/fadvise.c
*
* Copyright (C) 2002, Linus Torvalds
*
* 11Jan2003 Andrew Morton
* Initial version.
*/
#include <linux/kernel.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/pagemap.h>
#include <linux/backing-dev.h>
#include <linux/pagevec.h>
#include <linux/fadvise.h>
#include <linux/writeback.h>
#include <linux/syscalls.h>
#include <linux/swap.h>
#include <asm/unistd.h>
/*
* POSIX_FADV_WILLNEED could set PG_Referenced, and POSIX_FADV_NOREUSE could
* deactivate the pages and clear PG_Referenced.
*/
SYSCALL_DEFINE4(fadvise64_64, int, fd, loff_t, offset, loff_t, len, int, advice)
{
struct fd f = fdget(fd);
struct address_space *mapping;
struct backing_dev_info *bdi;
loff_t endbyte; /* inclusive */
pgoff_t start_index;
pgoff_t end_index;
unsigned long nrpages;
int ret = 0;
if (!f.file)
return -EBADF;
if (S_ISFIFO(file_inode(f.file)->i_mode)) {
ret = -ESPIPE;
goto out;
}
mapping = f.file->f_mapping;
if (!mapping || len < 0) {
ret = -EINVAL;
goto out;
}
if (mapping->a_ops->get_xip_mem) {
switch (advice) {
case POSIX_FADV_NORMAL:
case POSIX_FADV_RANDOM:
case POSIX_FADV_SEQUENTIAL:
case POSIX_FADV_WILLNEED:
case POSIX_FADV_NOREUSE:
case POSIX_FADV_DONTNEED:
/* no bad return value, but ignore advice */
break;
default:
ret = -EINVAL;
}
goto out;
}
/* Careful about overflows. Len == 0 means "as much as possible" */
endbyte = offset + len;
if (!len || endbyte < len)
endbyte = -1;
else
endbyte--; /* inclusive */
bdi = mapping->backing_dev_info;
switch (advice) {
case POSIX_FADV_NORMAL:
f.file->f_ra.ra_pages = bdi->ra_pages;
spin_lock(&f.file->f_lock);
f.file->f_mode &= ~FMODE_RANDOM;
spin_unlock(&f.file->f_lock);
break;
case POSIX_FADV_RANDOM:
spin_lock(&f.file->f_lock);
f.file->f_mode |= FMODE_RANDOM;
spin_unlock(&f.file->f_lock);
break;
case POSIX_FADV_SEQUENTIAL:
f.file->f_ra.ra_pages = bdi->ra_pages * 2;
spin_lock(&f.file->f_lock);
f.file->f_mode &= ~FMODE_RANDOM;
spin_unlock(&f.file->f_lock);
break;
case POSIX_FADV_WILLNEED:
/* First and last PARTIAL page! */
start_index = offset >> PAGE_CACHE_SHIFT;
end_index = endbyte >> PAGE_CACHE_SHIFT;
/* Careful about overflow on the "+1" */
nrpages = end_index - start_index + 1;
if (!nrpages)
nrpages = ~0UL;
/*
* Ignore return value because fadvise() shall return
* success even if filesystem can't retrieve a hint,
*/
force_page_cache_readahead(mapping, f.file, start_index,
nrpages);
break;
case POSIX_FADV_NOREUSE:
break;
case POSIX_FADV_DONTNEED:
if (!bdi_write_congested(mapping->backing_dev_info))
__filemap_fdatawrite_range(mapping, offset, endbyte,
WB_SYNC_NONE);
/*
* First and last FULL page! Partial pages are deliberately
* preserved on the expectation that it is better to preserve
* needed memory than to discard unneeded memory.
*/
start_index = (offset+(PAGE_CACHE_SIZE-1)) >> PAGE_CACHE_SHIFT;
end_index = (endbyte >> PAGE_CACHE_SHIFT);
if (end_index >= start_index) {
unsigned long count = invalidate_mapping_pages(mapping,
start_index, end_index);
/*
* If fewer pages were invalidated than expected then
* it is possible that some of the pages were on
* a per-cpu pagevec for a remote CPU. Drain all
* pagevecs and try again.
*/
if (count < (end_index - start_index + 1)) {
lru_add_drain_all();
invalidate_mapping_pages(mapping, start_index,
end_index);
}
}
break;
default:
ret = -EINVAL;
}
out:
fdput(f);
return ret;
}
#ifdef __ARCH_WANT_SYS_FADVISE64
SYSCALL_DEFINE4(fadvise64, int, fd, loff_t, offset, size_t, len, int, advice)
{
return sys_fadvise64_64(fd, offset, len, advice);
}
#endif
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