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arm64: add PTE_UXN/PTE_WRITE to SWAPPER_*_FLAGS

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With PIE enabled, the swapper PTEs would have a Permission Indirection Index
(PIIndex) of 0. A PIIndex of 0 is not currently used by any other PTEs.

To avoid using index 0 specifically for the swapper PTEs, mark them as
PTE_UXN and PTE_WRITE, so that they map to a PAGE_KERNEL_EXEC equivalent.

This also adds PTE_WRITE to KPTI_NG_PTE_FLAGS, which was tested by booting
with kpti=on.

Signed-off-by: Joey Gouly <joey.gouly@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20230606145859.697944-12-joey.gouly@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Joey Gouly 2023-06-06 15:58:50 +01:00 committed by Catalin Marinas
parent 8ef67c67e6
commit f0af339fc4
3 changed files with 10 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
arch/arm64/include/asm/kernel-pgtable.h
View File

@ -107,14 +107,14 @@
/*
* Initial memory map attributes.
*/
#define SWAPPER_PTE_FLAGS (PTE_TYPE_PAGE | PTE_AF | PTE_SHARED)
#define SWAPPER_PMD_FLAGS (PMD_TYPE_SECT | PMD_SECT_AF | PMD_SECT_S)
#define SWAPPER_PTE_FLAGS (PTE_TYPE_PAGE | PTE_AF | PTE_SHARED | PTE_UXN)
#define SWAPPER_PMD_FLAGS (PMD_TYPE_SECT | PMD_SECT_AF | PMD_SECT_S | PTE_UXN)
#ifdef CONFIG_ARM64_4K_PAGES
#define SWAPPER_RW_MMUFLAGS (PMD_ATTRINDX(MT_NORMAL) | SWAPPER_PMD_FLAGS)
#define SWAPPER_RW_MMUFLAGS (PMD_ATTRINDX(MT_NORMAL) | SWAPPER_PMD_FLAGS | PTE_WRITE)
#define SWAPPER_RX_MMUFLAGS (SWAPPER_RW_MMUFLAGS | PMD_SECT_RDONLY)
#else
#define SWAPPER_RW_MMUFLAGS (PTE_ATTRINDX(MT_NORMAL) | SWAPPER_PTE_FLAGS)
#define SWAPPER_RW_MMUFLAGS (PTE_ATTRINDX(MT_NORMAL) | SWAPPER_PTE_FLAGS | PTE_WRITE)
#define SWAPPER_RX_MMUFLAGS (SWAPPER_RW_MMUFLAGS | PTE_RDONLY)
#endif

8
arch/arm64/kernel/head.S
View File

@ -382,7 +382,7 @@ SYM_FUNC_START_LOCAL(create_idmap)
adrp x0, init_idmap_pg_dir
adrp x3, _text
adrp x6, _end + MAX_FDT_SIZE + SWAPPER_BLOCK_SIZE
mov x7, SWAPPER_RX_MMUFLAGS
mov_q x7, SWAPPER_RX_MMUFLAGS
map_memory x0, x1, x3, x6, x7, x3, IDMAP_PGD_ORDER, x10, x11, x12, x13, x14, EXTRA_SHIFT
@ -391,7 +391,7 @@ SYM_FUNC_START_LOCAL(create_idmap)
adrp x2, init_pg_dir
adrp x3, init_pg_end
bic x4, x2, #SWAPPER_BLOCK_SIZE - 1
mov x5, SWAPPER_RW_MMUFLAGS
mov_q x5, SWAPPER_RW_MMUFLAGS
mov x6, #SWAPPER_BLOCK_SHIFT
bl remap_region
@ -402,7 +402,7 @@ SYM_FUNC_START_LOCAL(create_idmap)
bfi x22, x21, #0, #SWAPPER_BLOCK_SHIFT // remapped FDT address
add x3, x2, #MAX_FDT_SIZE + SWAPPER_BLOCK_SIZE
bic x4, x21, #SWAPPER_BLOCK_SIZE - 1
mov x5, SWAPPER_RW_MMUFLAGS
mov_q x5, SWAPPER_RW_MMUFLAGS
mov x6, #SWAPPER_BLOCK_SHIFT
bl remap_region
@ -430,7 +430,7 @@ SYM_FUNC_START_LOCAL(create_kernel_mapping)
adrp x3, _text // runtime __pa(_text)
sub x6, x6, x3 // _end - _text
add x6, x6, x5 // runtime __va(_end)
mov x7, SWAPPER_RW_MMUFLAGS
mov_q x7, SWAPPER_RW_MMUFLAGS
map_memory x0, x1, x5, x6, x7, x3, (VA_BITS - PGDIR_SHIFT), x10, x11, x12, x13, x14

4
arch/arm64/mm/proc.S
View File

@ -199,7 +199,7 @@ SYM_FUNC_END(idmap_cpu_replace_ttbr1)
#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
#define KPTI_NG_PTE_FLAGS (PTE_ATTRINDX(MT_NORMAL) | SWAPPER_PTE_FLAGS)
#define KPTI_NG_PTE_FLAGS (PTE_ATTRINDX(MT_NORMAL) | SWAPPER_PTE_FLAGS | PTE_WRITE)
.pushsection ".idmap.text", "a"
@ -290,7 +290,7 @@ SYM_TYPED_FUNC_START(idmap_kpti_install_ng_mappings)
isb
mov temp_pte, x5
mov pte_flags, #KPTI_NG_PTE_FLAGS
mov_q pte_flags, KPTI_NG_PTE_FLAGS
/* Everybody is enjoying the idmap, so we can rewrite swapper. */
/* PGD */