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author | Mark Rutland <mark.rutland@arm.com> | 2020-11-03 10:22:29 +0000 |
---|---|---|
committer | Catalin Marinas <catalin.marinas@arm.com> | 2020-11-10 17:30:40 +0000 |
commit | 833be850f1cabd0e3b5337c0fcab20a6e936dd48 (patch) | |
tree | f19034fb5146f82b4fc2944ec86fef62581335aa /arch/arm64 | |
parent | ba090f9cafd53dbabe0f0a8c4ccae44203d3731b (diff) | |
download | linux-833be850f1cabd0e3b5337c0fcab20a6e936dd48.tar.gz linux-833be850f1cabd0e3b5337c0fcab20a6e936dd48.tar.bz2 linux-833be850f1cabd0e3b5337c0fcab20a6e936dd48.zip |
arm64: consistently use reserved_pg_dir
Depending on configuration options and specific code paths, we either
use the empty_zero_page or the configuration-dependent reserved_ttbr0
as a reserved value for TTBR{0,1}_EL1.
To simplify this code, let's always allocate and use the same
reserved_pg_dir, replacing reserved_ttbr0. Note that this is allocated
(and hence pre-zeroed), and is also marked as read-only in the kernel
Image mapping.
Keeping this separate from the empty_zero_page potentially helps with
robustness as the empty_zero_page is used in a number of cases where a
failure to map it read-only could allow it to become corrupted.
The (presently unused) swapper_pg_end symbol is also removed, and
comments are added wherever we rely on the offsets between the
pre-allocated pg_dirs to keep these cases easily identifiable.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20201103102229.8542-1-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64')
-rw-r--r-- | arch/arm64/include/asm/asm-uaccess.h | 4 | ||||
-rw-r--r-- | arch/arm64/include/asm/kernel-pgtable.h | 6 | ||||
-rw-r--r-- | arch/arm64/include/asm/mmu_context.h | 6 | ||||
-rw-r--r-- | arch/arm64/include/asm/pgtable.h | 1 | ||||
-rw-r--r-- | arch/arm64/include/asm/uaccess.h | 4 | ||||
-rw-r--r-- | arch/arm64/kernel/entry.S | 6 | ||||
-rw-r--r-- | arch/arm64/kernel/setup.c | 2 | ||||
-rw-r--r-- | arch/arm64/kernel/vmlinux.lds.S | 8 | ||||
-rw-r--r-- | arch/arm64/mm/proc.S | 2 |
9 files changed, 17 insertions, 22 deletions
diff --git a/arch/arm64/include/asm/asm-uaccess.h b/arch/arm64/include/asm/asm-uaccess.h index f68a0e64482a..5ef624fef44a 100644 --- a/arch/arm64/include/asm/asm-uaccess.h +++ b/arch/arm64/include/asm/asm-uaccess.h @@ -15,10 +15,10 @@ .macro __uaccess_ttbr0_disable, tmp1 mrs \tmp1, ttbr1_el1 // swapper_pg_dir bic \tmp1, \tmp1, #TTBR_ASID_MASK - sub \tmp1, \tmp1, #RESERVED_TTBR0_SIZE // reserved_ttbr0 just before swapper_pg_dir + sub \tmp1, \tmp1, #PAGE_SIZE // reserved_pg_dir just before swapper_pg_dir msr ttbr0_el1, \tmp1 // set reserved TTBR0_EL1 isb - add \tmp1, \tmp1, #RESERVED_TTBR0_SIZE + add \tmp1, \tmp1, #PAGE_SIZE msr ttbr1_el1, \tmp1 // set reserved ASID isb .endm diff --git a/arch/arm64/include/asm/kernel-pgtable.h b/arch/arm64/include/asm/kernel-pgtable.h index 19ca76ea60d9..587c504a4c8b 100644 --- a/arch/arm64/include/asm/kernel-pgtable.h +++ b/arch/arm64/include/asm/kernel-pgtable.h @@ -89,12 +89,6 @@ #define INIT_DIR_SIZE (PAGE_SIZE * EARLY_PAGES(KIMAGE_VADDR, _end)) #define IDMAP_DIR_SIZE (IDMAP_PGTABLE_LEVELS * PAGE_SIZE) -#ifdef CONFIG_ARM64_SW_TTBR0_PAN -#define RESERVED_TTBR0_SIZE (PAGE_SIZE) -#else -#define RESERVED_TTBR0_SIZE (0) -#endif - /* Initial memory map size */ #if ARM64_SWAPPER_USES_SECTION_MAPS #define SWAPPER_BLOCK_SHIFT SECTION_SHIFT diff --git a/arch/arm64/include/asm/mmu_context.h b/arch/arm64/include/asm/mmu_context.h index 0672236e1aea..5c72c20bd300 100644 --- a/arch/arm64/include/asm/mmu_context.h +++ b/arch/arm64/include/asm/mmu_context.h @@ -36,11 +36,11 @@ static inline void contextidr_thread_switch(struct task_struct *next) } /* - * Set TTBR0 to empty_zero_page. No translations will be possible via TTBR0. + * Set TTBR0 to reserved_pg_dir. No translations will be possible via TTBR0. */ static inline void cpu_set_reserved_ttbr0(void) { - unsigned long ttbr = phys_to_ttbr(__pa_symbol(empty_zero_page)); + unsigned long ttbr = phys_to_ttbr(__pa_symbol(reserved_pg_dir)); write_sysreg(ttbr, ttbr0_el1); isb(); @@ -195,7 +195,7 @@ static inline void update_saved_ttbr0(struct task_struct *tsk, return; if (mm == &init_mm) - ttbr = __pa_symbol(empty_zero_page); + ttbr = __pa_symbol(reserved_pg_dir); else ttbr = virt_to_phys(mm->pgd) | ASID(mm) << 48; diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index 4ff12a7adcfd..74694e129f9a 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -519,6 +519,7 @@ extern pgd_t swapper_pg_dir[PTRS_PER_PGD]; extern pgd_t idmap_pg_dir[PTRS_PER_PGD]; extern pgd_t idmap_pg_end[]; extern pgd_t tramp_pg_dir[PTRS_PER_PGD]; +extern pgd_t reserved_pg_dir[PTRS_PER_PGD]; extern void set_swapper_pgd(pgd_t *pgdp, pgd_t pgd); diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h index 991dd5f031e4..385a189f7d39 100644 --- a/arch/arm64/include/asm/uaccess.h +++ b/arch/arm64/include/asm/uaccess.h @@ -113,8 +113,8 @@ static inline void __uaccess_ttbr0_disable(void) local_irq_save(flags); ttbr = read_sysreg(ttbr1_el1); ttbr &= ~TTBR_ASID_MASK; - /* reserved_ttbr0 placed before swapper_pg_dir */ - write_sysreg(ttbr - RESERVED_TTBR0_SIZE, ttbr0_el1); + /* reserved_pg_dir placed before swapper_pg_dir */ + write_sysreg(ttbr - PAGE_SIZE, ttbr0_el1); isb(); /* Set reserved ASID */ write_sysreg(ttbr, ttbr1_el1); diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index b295fb912b12..6f31c2c06788 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -807,9 +807,10 @@ SYM_CODE_END(ret_to_user) */ .pushsection ".entry.tramp.text", "ax" + // Move from tramp_pg_dir to swapper_pg_dir .macro tramp_map_kernel, tmp mrs \tmp, ttbr1_el1 - add \tmp, \tmp, #(PAGE_SIZE + RESERVED_TTBR0_SIZE) + add \tmp, \tmp, #(2 * PAGE_SIZE) bic \tmp, \tmp, #USER_ASID_FLAG msr ttbr1_el1, \tmp #ifdef CONFIG_QCOM_FALKOR_ERRATUM_1003 @@ -826,9 +827,10 @@ alternative_else_nop_endif #endif /* CONFIG_QCOM_FALKOR_ERRATUM_1003 */ .endm + // Move from swapper_pg_dir to tramp_pg_dir .macro tramp_unmap_kernel, tmp mrs \tmp, ttbr1_el1 - sub \tmp, \tmp, #(PAGE_SIZE + RESERVED_TTBR0_SIZE) + sub \tmp, \tmp, #(2 * PAGE_SIZE) orr \tmp, \tmp, #USER_ASID_FLAG msr ttbr1_el1, \tmp /* diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c index 133257ffd859..c28a9ec76b11 100644 --- a/arch/arm64/kernel/setup.c +++ b/arch/arm64/kernel/setup.c @@ -366,7 +366,7 @@ void __init __no_sanitize_address setup_arch(char **cmdline_p) * faults in case uaccess_enable() is inadvertently called by the init * thread. */ - init_task.thread_info.ttbr0 = __pa_symbol(empty_zero_page); + init_task.thread_info.ttbr0 = __pa_symbol(reserved_pg_dir); #endif if (boot_args[1] || boot_args[2] || boot_args[3]) { diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S index 1bda604f4c70..30c102978942 100644 --- a/arch/arm64/kernel/vmlinux.lds.S +++ b/arch/arm64/kernel/vmlinux.lds.S @@ -164,13 +164,11 @@ SECTIONS . += PAGE_SIZE; #endif -#ifdef CONFIG_ARM64_SW_TTBR0_PAN - reserved_ttbr0 = .; - . += RESERVED_TTBR0_SIZE; -#endif + reserved_pg_dir = .; + . += PAGE_SIZE; + swapper_pg_dir = .; . += PAGE_SIZE; - swapper_pg_end = .; . = ALIGN(SEGMENT_ALIGN); __init_begin = .; diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S index 23c326a06b2d..0eaf16b0442a 100644 --- a/arch/arm64/mm/proc.S +++ b/arch/arm64/mm/proc.S @@ -168,7 +168,7 @@ SYM_FUNC_END(cpu_do_resume) .pushsection ".idmap.text", "awx" .macro __idmap_cpu_set_reserved_ttbr1, tmp1, tmp2 - adrp \tmp1, empty_zero_page + adrp \tmp1, reserved_pg_dir phys_to_ttbr \tmp2, \tmp1 offset_ttbr1 \tmp2, \tmp1 msr ttbr1_el1, \tmp2 |