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| author | Ard Biesheuvel <ardb@kernel.org> | 2021-03-10 11:49:41 +0100 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2021-03-19 18:50:45 +0000 |
| commit | 87143f404f338dbf0b51374ea48ab05e598af564 (patch) | |
| tree | 3909d7a6a9afb16d331eb60ebd16314b6e777dcc /arch/arm64/include/asm/pgtable-hwdef.h | |
| parent | c1fd78a77704318de34ba4b780cd99a5ef96d162 (diff) | |
| download | linux-87143f404f338dbf0b51374ea48ab05e598af564.tar.bz2 | |
arm64: mm: use XN table mapping attributes for the linear region
The way the arm64 kernel virtual address space is constructed guarantees
that swapper PGD entries are never shared between the linear region on
the one hand, and the vmalloc region on the other, which is where all
kernel text, module text and BPF text mappings reside.
This means that mappings in the linear region (which never require
executable permissions) never share any table entries at any level with
mappings that do require executable permissions, and so we can set the
table-level PXN attributes for all table entries that are created while
setting up mappings in the linear region. Since swapper's PGD level page
table is mapped r/o itself, this adds another layer of robustness to the
way the kernel manages its own page tables. While at it, set the UXN
attribute as well for all kernel mappings created at boot.
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Link: https://lore.kernel.org/r/20210310104942.174584-3-ardb@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/include/asm/pgtable-hwdef.h')
| -rw-r--r-- | arch/arm64/include/asm/pgtable-hwdef.h | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/pgtable-hwdef.h b/arch/arm64/include/asm/pgtable-hwdef.h index e64e77a345b2..b82575a33f8b 100644 --- a/arch/arm64/include/asm/pgtable-hwdef.h +++ b/arch/arm64/include/asm/pgtable-hwdef.h @@ -101,6 +101,8 @@ #define P4D_TYPE_MASK (_AT(p4dval_t, 3) << 0) #define P4D_TYPE_SECT (_AT(p4dval_t, 1) << 0) #define P4D_SECT_RDONLY (_AT(p4dval_t, 1) << 7) /* AP[2] */ +#define P4D_TABLE_PXN (_AT(p4dval_t, 1) << 59) +#define P4D_TABLE_UXN (_AT(p4dval_t, 1) << 60) /* * Level 1 descriptor (PUD). @@ -110,6 +112,8 @@ #define PUD_TYPE_MASK (_AT(pudval_t, 3) << 0) #define PUD_TYPE_SECT (_AT(pudval_t, 1) << 0) #define PUD_SECT_RDONLY (_AT(pudval_t, 1) << 7) /* AP[2] */ +#define PUD_TABLE_PXN (_AT(pudval_t, 1) << 59) +#define PUD_TABLE_UXN (_AT(pudval_t, 1) << 60) /* * Level 2 descriptor (PMD). @@ -131,6 +135,8 @@ #define PMD_SECT_CONT (_AT(pmdval_t, 1) << 52) #define PMD_SECT_PXN (_AT(pmdval_t, 1) << 53) #define PMD_SECT_UXN (_AT(pmdval_t, 1) << 54) +#define PMD_TABLE_PXN (_AT(pmdval_t, 1) << 59) +#define PMD_TABLE_UXN (_AT(pmdval_t, 1) << 60) /* * AttrIndx[2:0] encoding (mapping attributes defined in the MAIR* registers). |