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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/include/asm/mmu_context.h | |
| parent | ba090f9cafd53dbabe0f0a8c4ccae44203d3731b (diff) | |
| download | lwn-833be850f1cabd0e3b5337c0fcab20a6e936dd48.tar.gz lwn-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/include/asm/mmu_context.h')
| -rw-r--r-- | arch/arm64/include/asm/mmu_context.h | 6 |
1 files changed, 3 insertions, 3 deletions
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; |