diff options
| author | Will Deacon <will.deacon@arm.com> | 2017-11-14 14:14:17 +0000 |
|---|---|---|
| committer | Amit Pundir <amit.pundir@linaro.org> | 2018-01-22 13:16:20 +0530 |
| commit | 3100a4b4f4e349e6e8f4b104eef64d03441623bc (patch) | |
| tree | f9ac6ddd01d8763d3d66a5386fb706c8dd1125b9 /arch/arm64/mm/mmu.c | |
| parent | 5b6527383726be9b60cc596da4fae04b7d725e7a (diff) | |
FROMLIST: arm64: mm: Map entry trampoline into trampoline and kernel page tables
The exception entry trampoline needs to be mapped at the same virtual
address in both the trampoline page table (which maps nothing else)
and also the kernel page table, so that we can swizzle TTBR1_EL1 on
exceptions from and return to EL0.
This patch maps the trampoline at a fixed virtual address in the fixmap
area of the kernel virtual address space, which allows the kernel proper
to be randomized with respect to the trampoline when KASLR is enabled.
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Laura Abbott <labbott@redhat.com>
Tested-by: Shanker Donthineni <shankerd@codeaurora.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
(cherry picked from git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git
commit 51a0048beb449682d632d0af52a515adb9f9882e)
Change-Id: I31b2dcdf4db36c3e31181fe43ccb984f9efb6ac6
[ghackmann@google.com:
- adjust context
- tweak __create_pgd_mapping() call to match 4.4 APIs]
Signed-off-by: Greg Hackmann <ghackmann@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Diffstat (limited to 'arch/arm64/mm/mmu.c')
| -rw-r--r-- | arch/arm64/mm/mmu.c | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index 358536be66f0..a787c75d1e65 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -485,6 +485,29 @@ static void __init map_kernel_segment(pgd_t *pgd, void *va_start, void *va_end, vm_area_add_early(vma); } +#ifdef CONFIG_UNMAP_KERNEL_AT_EL0 +static int __init map_entry_trampoline(void) +{ + extern char __entry_tramp_text_start[]; + + pgprot_t prot = PAGE_KERNEL_EXEC; + phys_addr_t pa_start = __pa_symbol(__entry_tramp_text_start); + + /* The trampoline is always mapped and can therefore be global */ + pgprot_val(prot) &= ~PTE_NG; + + /* Map only the text into the trampoline page table */ + memset(tramp_pg_dir, 0, PGD_SIZE); + __create_pgd_mapping(tramp_pg_dir, pa_start, TRAMP_VALIAS, PAGE_SIZE, + prot, late_pgtable_alloc); + + /* ...as well as the kernel page table */ + __set_fixmap(FIX_ENTRY_TRAMP_TEXT, pa_start, prot); + return 0; +} +core_initcall(map_entry_trampoline); +#endif + /* * Create fine-grained mappings for the kernel. */ |