From: Anshuman Khandual anshuman.khandual@arm.com
[ Upstream commit 9163f01130304fab1f74683d7d44632da7bda637 ]
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: 529c4b05a3cb ("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.khandua... Signed-off-by: Will Deacon will@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- arch/arm64/include/asm/mmu_context.h | 4 ++-- arch/arm64/kernel/setup.c | 2 +- 2 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 68028de06d18..5a54a5ab5f92 100644 --- a/arch/arm64/include/asm/mmu_context.h +++ b/arch/arm64/include/asm/mmu_context.h @@ -192,9 +192,9 @@ 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); } diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c index c28a9ec76b11..eb4b24652c10 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(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]) {