Commit 6b9c98e6 authored by Ard Biesheuvel's avatar Ard Biesheuvel Committed by Catalin Marinas
Browse files

arm64/efi: Move uaccess en/disable out of efi_set_pgd() 



efi_set_pgd() will no longer be called when invoking EFI runtime
services via the efi_rts_wq work queue, but the uaccess en/disable are
still needed when using PAN emulation using TTBR0 switching. So move
these into the callers.

Acked-by: default avatarWill Deacon <will@kernel.org>
Signed-off-by: default avatarArd Biesheuvel <ardb@kernel.org>
Acked-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent 1068cb52

arch/arm64/include/asm/efi.h

+3 −10
Original line number Diff line number Diff line
@@ -126,21 +126,14 @@ static inline void efi_set_pgd(struct mm_struct *mm) 
		if (mm != current->active_mm) {

			/*

			 * Update the current thread's saved ttbr0 since it is

			 * restored as part of a return from exception. Enable

			 * access to the valid TTBR0_EL1 and invoke the errata

			 * workaround directly since there is no return from

			 * exception when invoking the EFI run-time services.

			 * restored as part of a return from exception.

			 */

			update_saved_ttbr0(current, mm);

			uaccess_ttbr0_enable();

			post_ttbr_update_workaround();

		} else {

			/*

			 * Defer the switch to the current thread's TTBR0_EL1

			 * until uaccess_enable(). Restore the current

			 * thread's saved ttbr0 corresponding to its active_mm

			 * Restore the current thread's saved ttbr0

			 * corresponding to its active_mm

			 */

			uaccess_ttbr0_disable();

			update_saved_ttbr0(current, current->active_mm);

		}

	}

arch/arm64/kernel/efi.c

+18 −0
Original line number Diff line number Diff line
@@ -169,12 +169,30 @@ void arch_efi_call_virt_setup(void) 
{

	efi_runtime_assert_lock_held();

	efi_virtmap_load();



	/*

	 * Enable access to the valid TTBR0_EL1 and invoke the errata

	 * workaround directly since there is no return from exception when

	 * invoking the EFI run-time services.

	 */

	uaccess_ttbr0_enable();

	post_ttbr_update_workaround();



	__efi_fpsimd_begin();

}



void arch_efi_call_virt_teardown(void)

{

	__efi_fpsimd_end();



	/*

	 * Defer the switch to the current thread's TTBR0_EL1 until

	 * uaccess_enable(). Do so before efi_virtmap_unload() updates the

	 * saved TTBR0 value, so the userland page tables are not activated

	 * inadvertently over the back of an exception.

	 */

	uaccess_ttbr0_disable();



	efi_virtmap_unload();

}