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authorCatalin Marinas <catalin.marinas@arm.com>2019-11-27 11:00:27 +0100
committerCatalin Marinas <catalin.marinas@arm.com>2020-09-04 13:46:07 +0200
commit9f3419315f3cdc41a7318e4d50ba18a592b30c8c (patch)
tree6c3bd9f4b62d991a83d5bb203321b63c2b43efbd /fs/proc
parentmm: Introduce arch_calc_vm_flag_bits() (diff)
downloadlinux-9f3419315f3cdc41a7318e4d50ba18a592b30c8c.tar.xz
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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 'fs/proc')
-rw-r--r--fs/proc/task_mmu.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 5066b0251ed8..35172a91148e 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -653,6 +653,10 @@ static void show_smap_vma_flags(struct seq_file *m, struct vm_area_struct *vma)
[ilog2(VM_MERGEABLE)] = "mg",
[ilog2(VM_UFFD_MISSING)]= "um",
[ilog2(VM_UFFD_WP)] = "uw",
+#ifdef CONFIG_ARM64_MTE
+ [ilog2(VM_MTE)] = "mt",
+ [ilog2(VM_MTE_ALLOWED)] = "",
+#endif
#ifdef CONFIG_ARCH_HAS_PKEYS
/* These come out via ProtectionKey: */
[ilog2(VM_PKEY_BIT0)] = "",