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

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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 <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: James Morse <[email protected]>
Cc: [email protected]
Cc: [email protected]
Fixes: 529c4b05a3 ("arm64: handle 52-bit addresses in TTBR")
Signed-off-by: Anshuman Khandual <[email protected]>
Reviewed-by: Catalin Marinas <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Will Deacon <[email protected]>
This commit is contained in:
Anshuman Khandual authored and Will Deacon committed 2021-06-15 19:03:24 +01:00
1 parent 84c5e23ede
commit 9163f01130
2 files changed
+3 -3
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arch/arm64/include/asm/mmu_context.h
+2 -2
View File
@@ -177,9 +177,9 @@ static inline void update_saved_ttbr0(struct task_struct *tsk,
return;
if (mm == &init_mm)
ttbr = __pa_symbol(reserved_pg_dir);
ttbr = phys_to_ttbr(__pa_symbol(reserved_pg_dir));
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);
}
arch/arm64/kernel/setup.c
+1 -1
View File
@@ -381,7 +381,7 @@ 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(reserved_pg_dir);
init_task.thread_info.ttbr0 = phys_to_ttbr(__pa_symbol(reserved_pg_dir));
#endif
if (boot_args[1] || boot_args[2] || boot_args[3]) {