diff options
| author | Heiko Carstens <hca@linux.ibm.com> | 2024-07-29 13:06:44 +0200 |
|---|---|---|
| committer | Vasily Gorbik <gor@linux.ibm.com> | 2024-07-31 16:30:20 +0200 |
| commit | 33bd8d153c337ba9b30a2e5994437ca703ab4ed8 (patch) | |
| tree | e68f63f074da9d10d898bb3b03bff5a5adf0066c /arch/s390/mm/init.c | |
| parent | s390/vmlinux.lds.S: Move ro_after_init section behind rodata section (diff) | |
| download | linux-33bd8d153c337ba9b30a2e5994437ca703ab4ed8.tar.xz linux-33bd8d153c337ba9b30a2e5994437ca703ab4ed8.zip | |
s390: Keep inittext section writable
There is no added security by making the inittext section non-writable,
however it does split part of the kernel mapping into 4K mappings
instead of 1M mappings:
---[ Kernel Image Start ]---
0x000003ffe0000000-0x000003ffe0e00000 14M PMD RO X
0x000003ffe0e00000-0x000003ffe0ec7000 796K PTE RO X
0x000003ffe0ec7000-0x000003ffe0f00000 228K PTE RO NX
0x000003ffe0f00000-0x000003ffe1300000 4M PMD RO NX
0x000003ffe1300000-0x000003ffe1353000 332K PTE RO NX
0x000003ffe1353000-0x000003ffe1400000 692K PTE RW NX
0x000003ffe1400000-0x000003ffe1500000 1M PMD RW NX
0x000003ffe1500000-0x000003ffe1700000 2M PTE RW NX <---
0x000003ffe1700000-0x000003ffe1800000 1M PMD RW NX
0x000003ffe1800000-0x000003ffe187e000 504K PTE RW NX
---[ Kernel Image End ]---
Keep the inittext writable and enable instruction execution protection
(aka noexec) later to prevent this. This also allows to use the
generic free_initmem() implementation.
---[ Kernel Image Start ]---
0x000003ffe0000000-0x000003ffe0e00000 14M PMD RO X
0x000003ffe0e00000-0x000003ffe0ec7000 796K PTE RO X
0x000003ffe0ec7000-0x000003ffe0f00000 228K PTE RO NX
0x000003ffe0f00000-0x000003ffe1300000 4M PMD RO NX
0x000003ffe1300000-0x000003ffe1353000 332K PTE RO NX
0x000003ffe1353000-0x000003ffe1400000 692K PTE RW NX
0x000003ffe1400000-0x000003ffe1800000 4M PMD RW NX <---
0x000003ffe1800000-0x000003ffe187e000 504K PTE RW NX
---[ Kernel Image End ]---
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Diffstat (limited to 'arch/s390/mm/init.c')
| -rw-r--r-- | arch/s390/mm/init.c | 9 |
1 files changed, 2 insertions, 7 deletions
diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c index ddcd39ef4346..e3d258f9e726 100644 --- a/arch/s390/mm/init.c +++ b/arch/s390/mm/init.c @@ -108,6 +108,8 @@ void mark_rodata_ro(void) { unsigned long size = __end_ro_after_init - __start_ro_after_init; + if (MACHINE_HAS_NX) + system_ctl_set_bit(0, CR0_INSTRUCTION_EXEC_PROTECTION_BIT); __set_memory_ro(__start_ro_after_init, __end_ro_after_init); pr_info("Write protected read-only-after-init data: %luk\n", size >> 10); } @@ -170,13 +172,6 @@ void __init mem_init(void) setup_zero_pages(); /* Setup zeroed pages. */ } -void free_initmem(void) -{ - set_memory_rwnx((unsigned long)_sinittext, - (unsigned long)(_einittext - _sinittext) >> PAGE_SHIFT); - free_initmem_default(POISON_FREE_INITMEM); -} - unsigned long memory_block_size_bytes(void) { /* |