| Message ID | 20230309145246.22787-13-joey.gouly@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Permission Indirection Extension | expand |
On Thu, Mar 09, 2023 at 02:52:40PM +0000, Joey Gouly wrote: > 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. > > Signed-off-by: Joey Gouly <joey.gouly@arm.com> > Cc: Catalin Marinas <catalin.marinas@arm.com> > Cc: Will Deacon <will@kernel.org> > Cc: Mark Rutland <mark.rutland@arm.com> > --- > arch/arm64/include/asm/kernel-pgtable.h | 4 ++-- > arch/arm64/kernel/head.S | 8 ++++---- > arch/arm64/mm/proc.S | 2 +- > 3 files changed, 7 insertions(+), 7 deletions(-) > > diff --git a/arch/arm64/include/asm/kernel-pgtable.h b/arch/arm64/include/asm/kernel-pgtable.h > index fcd14197756f..daf1909116f6 100644 > --- a/arch/arm64/include/asm/kernel-pgtable.h > +++ b/arch/arm64/include/asm/kernel-pgtable.h > @@ -104,8 +104,8 @@ > /* > * 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 | PTE_WRITE) > +#define SWAPPER_PMD_FLAGS (PMD_TYPE_SECT | PMD_SECT_AF | PMD_SECT_S | PTE_UXN | PTE_WRITE) Adding PTE_UXN is fine but we have SWAPPER_RX_MMUFLAGS which is no longer read-only after this change. I don't think this matters much as IIUC we only use init_pg_dir briefly before creating the proper swapper_pg_dir.
diff --git a/arch/arm64/include/asm/kernel-pgtable.h b/arch/arm64/include/asm/kernel-pgtable.h index fcd14197756f..daf1909116f6 100644 --- a/arch/arm64/include/asm/kernel-pgtable.h +++ b/arch/arm64/include/asm/kernel-pgtable.h @@ -104,8 +104,8 @@ /* * 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 | PTE_WRITE) +#define SWAPPER_PMD_FLAGS (PMD_TYPE_SECT | PMD_SECT_AF | PMD_SECT_S | PTE_UXN | PTE_WRITE) #ifdef CONFIG_ARM64_4K_PAGES #define SWAPPER_RW_MMUFLAGS (PMD_ATTRINDX(MT_NORMAL) | SWAPPER_PMD_FLAGS) diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index b98970907226..989e2132af14 100644 --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -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 diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S index 91410f488090..644e8daa25df 100644 --- a/arch/arm64/mm/proc.S +++ b/arch/arm64/mm/proc.S @@ -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 */
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. Signed-off-by: Joey Gouly <joey.gouly@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> --- arch/arm64/include/asm/kernel-pgtable.h | 4 ++-- arch/arm64/kernel/head.S | 8 ++++---- arch/arm64/mm/proc.S | 2 +- 3 files changed, 7 insertions(+), 7 deletions(-)