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arm64/mm: Fix ttbr0 values stored in struct thread_info for software-pan

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[ Upstream commit 9163f01130 ]

When using CONFIG_ARM64_SW_TTBR0_PAN, a task's thread_info::ttbr0 must be
the TTBR0_EL1 value used to run userspace. With 52-bit PAs, the PA must be
packed into the TTBR using phys_to_ttbr(), but we forget to do this in some
of the SW PAN code. Thus, if the value is installed into TTBR0_EL1 (as may
happen in the uaccess routines), this could result in UNPREDICTABLE
behaviour.

Since hardware with 52-bit PA support almost certainly has HW PAN, which
will be used in preference, this shouldn't be a practical issue, but let's
fix this for consistency.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Fixes: 529c4b05a3 ("arm64: handle 52-bit addresses in TTBR")
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/1623749578-11231-1-git-send-email-anshuman.khandual@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Anshuman Khandual
2021-06-15 15:02:58 +05:30
committed by Greg Kroah-Hartman
parent 8d6acfe80d
commit bb5e089df7
2 changed files with 3 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
arch/arm64/include/asm/mmu_context.h
View File

@@ -192,9 +192,9 @@ static inline void update_saved_ttbr0(struct task_struct *tsk,
return; return;
if (mm == &init_mm) if (mm == &init_mm)
ttbr = __pa_symbol(reserved_pg_dir); ttbr = phys_to_ttbr(__pa_symbol(reserved_pg_dir));
else else
ttbr = virt_to_phys(mm->pgd) | ASID(mm) << 48; ttbr = phys_to_ttbr(virt_to_phys(mm->pgd)) | ASID(mm) << 48;
WRITE_ONCE(task_thread_info(tsk)->ttbr0, ttbr); WRITE_ONCE(task_thread_info(tsk)->ttbr0, ttbr);
} }

2
arch/arm64/kernel/setup.c
View File

@@ -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 * faults in case uaccess_enable() is inadvertently called by the init
* thread. * thread.
*/ */
init_task.thread_info.ttbr0 = __pa_symbol(reserved_pg_dir); init_task.thread_info.ttbr0 = phys_to_ttbr(__pa_symbol(reserved_pg_dir));
#endif #endif
if (boot_args[1] || boot_args[2] || boot_args[3]) { if (boot_args[1] || boot_args[2] || boot_args[3]) {