diff options
| author | Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> | 2017-03-30 14:05:21 +0300 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2017-04-01 13:12:29 +0300 |
| commit | f4ea6dcb08ea2c6c996c373573caf74d48d23b84 (patch) | |
| tree | 45023c9b39b10ace9efabcc860d8f01009e89520 /arch/powerpc/mm/mmu_context_book3s64.c | |
| parent | fbfef9027c2a7ad9277755509fdb849dbccfe8c1 (diff) | |
| download | linux-f4ea6dcb08ea2c6c996c373573caf74d48d23b84.tar.xz | |
powerpc/mm: Enable mappings above 128TB
Not all user space application is ready to handle wide addresses. It's
known that at least some JIT compilers use higher bits in pointers to
encode their information. It collides with valid pointers with 512TB
addresses and leads to crashes.
To mitigate this, we are not going to allocate virtual address space
above 128TB by default.
But userspace can ask for allocation from full address space by
specifying hint address (with or without MAP_FIXED) above 128TB.
If hint address set above 128TB, but MAP_FIXED is not specified, we try
to look for unmapped area by specified address. If it's already
occupied, we look for unmapped area in *full* address space, rather than
from 128TB window.
This approach helps to easily make application's memory allocator aware
about large address space without manually tracking allocated virtual
address space.
This is going to be a per mmap decision. ie, we can have some mmaps with
larger addresses and other that do not.
A sample memory layout looks like:
10000000-10010000 r-xp 00000000 fc:00 9057045 /home/max_addr_512TB
10010000-10020000 r--p 00000000 fc:00 9057045 /home/max_addr_512TB
10020000-10030000 rw-p 00010000 fc:00 9057045 /home/max_addr_512TB
10029630000-10029660000 rw-p 00000000 00:00 0 [heap]
7fff834a0000-7fff834b0000 rw-p 00000000 00:00 0
7fff834b0000-7fff83670000 r-xp 00000000 fc:00 9177190 /lib/powerpc64le-linux-gnu/libc-2.23.so
7fff83670000-7fff83680000 r--p 001b0000 fc:00 9177190 /lib/powerpc64le-linux-gnu/libc-2.23.so
7fff83680000-7fff83690000 rw-p 001c0000 fc:00 9177190 /lib/powerpc64le-linux-gnu/libc-2.23.so
7fff83690000-7fff836a0000 rw-p 00000000 00:00 0
7fff836a0000-7fff836c0000 r-xp 00000000 00:00 0 [vdso]
7fff836c0000-7fff83700000 r-xp 00000000 fc:00 9177193 /lib/powerpc64le-linux-gnu/ld-2.23.so
7fff83700000-7fff83710000 r--p 00030000 fc:00 9177193 /lib/powerpc64le-linux-gnu/ld-2.23.so
7fff83710000-7fff83720000 rw-p 00040000 fc:00 9177193 /lib/powerpc64le-linux-gnu/ld-2.23.so
7fffdccf0000-7fffdcd20000 rw-p 00000000 00:00 0 [stack]
1000000000000-1000000010000 rw-p 00000000 00:00 0
1ffff83710000-1ffff83720000 rw-p 00000000 00:00 0
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/mm/mmu_context_book3s64.c')
| -rw-r--r-- | arch/powerpc/mm/mmu_context_book3s64.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/powerpc/mm/mmu_context_book3s64.c b/arch/powerpc/mm/mmu_context_book3s64.c index 7bc5b63034db..86719f6b5a7c 100644 --- a/arch/powerpc/mm/mmu_context_book3s64.c +++ b/arch/powerpc/mm/mmu_context_book3s64.c @@ -99,7 +99,7 @@ static int hash__init_new_context(struct mm_struct *mm) * mm->context.addr_limit. Default to max task size so that we copy the * default values to paca which will help us to handle slb miss early. */ - mm->context.addr_limit = TASK_SIZE_USER64; + mm->context.addr_limit = TASK_SIZE_128TB; /* * The old code would re-promote on fork, we don't do that when using |