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authorCatalin Marinas <catalin.marinas@arm.com>2019-11-27 13:00:27 +0300
committerCatalin Marinas <catalin.marinas@arm.com>2020-09-04 14:46:07 +0300
commit9f3419315f3cdc41a7318e4d50ba18a592b30c8c (patch)
tree6c3bd9f4b62d991a83d5bb203321b63c2b43efbd /arch/arm64/include/asm/pgtable.h
parentb3fbbea4c00220f62e6f7e2514466e6ee81f7f60 (diff)
arm64: mte: Add PROT_MTE support to mmap() and mprotect()
To enable tagging on a memory range, the user must explicitly opt in via a new PROT_MTE flag passed to mmap() or mprotect(). Since this is a new memory type in the AttrIndx field of a pte, simplify the or'ing of these bits over the protection_map[] attributes by making MT_NORMAL index 0. There are two conditions for arch_vm_get_page_prot() to return the MT_NORMAL_TAGGED memory type: (1) the user requested it via PROT_MTE, registered as VM_MTE in the vm_flags, and (2) the vma supports MTE, decided during the mmap() call (only) and registered as VM_MTE_ALLOWED. arch_calc_vm_prot_bits() is responsible for registering the user request as VM_MTE. The newly introduced arch_calc_vm_flag_bits() sets VM_MTE_ALLOWED if the mapping is MAP_ANONYMOUS. An MTE-capable filesystem (RAM-based) may be able to set VM_MTE_ALLOWED during its mmap() file ops call. In addition, update VM_DATA_DEFAULT_FLAGS to allow mprotect(PROT_MTE) on stack or brk area. The Linux mmap() syscall currently ignores unknown PROT_* flags. In the presence of MTE, an mmap(PROT_MTE) on a file which does not support MTE will not report an error and the memory will not be mapped as Normal Tagged. For consistency, mprotect(PROT_MTE) will not report an error either if the memory range does not support MTE. Two subsequent patches in the series will propose tightening of this behaviour. Co-developed-by: Vincenzo Frascino <vincenzo.frascino@arm.com> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org>
Diffstat (limited to 'arch/arm64/include/asm/pgtable.h')
-rw-r--r--arch/arm64/include/asm/pgtable.h7
1 files changed, 6 insertions, 1 deletions
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 0a205a8e91b2..057c40b6f5e0 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -681,8 +681,13 @@ static inline unsigned long p4d_page_vaddr(p4d_t p4d)
static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
{
+ /*
+ * Normal and Normal-Tagged are two different memory types and indices
+ * in MAIR_EL1. The mask below has to include PTE_ATTRINDX_MASK.
+ */
const pteval_t mask = PTE_USER | PTE_PXN | PTE_UXN | PTE_RDONLY |
- PTE_PROT_NONE | PTE_VALID | PTE_WRITE | PTE_GP;
+ PTE_PROT_NONE | PTE_VALID | PTE_WRITE | PTE_GP |
+ PTE_ATTRINDX_MASK;
/* preserve the hardware dirty information */
if (pte_hw_dirty(pte))
pte = pte_mkdirty(pte);