linux-kernel - [RFC PATCH 6/7] arm64/efi: Move uaccess en/disable out of efi_set

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250514174339.1834871-15-ardb+git@google.com>
Date: Wed, 14 May 2025 19:43:46 +0200
From: Ard Biesheuvel <ardb+git@...gle.com>
To: linux-efi@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
	Ard Biesheuvel <ardb@...nel.org>, Will Deacon <will@...nel.org>, Mark Rutland <mark.rutland@....com>, 
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>, Peter Zijlstra <peterz@...radead.org>
Subject: [RFC PATCH 6/7] arm64/efi: Move uaccess en/disable out of efi_set_pgd()

From: Ard Biesheuvel <ardb@...nel.org>

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.

Signed-off-by: Ard Biesheuvel <ardb@...nel.org>
---
 arch/arm64/include/asm/efi.h | 3 ---
 arch/arm64/kernel/efi.c      | 3 +++
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/efi.h b/arch/arm64/include/asm/efi.h
index decf87777f57..abe9176a3a23 100644
--- a/arch/arm64/include/asm/efi.h
+++ b/arch/arm64/include/asm/efi.h
@@ -132,15 +132,12 @@ static inline void efi_set_pgd(struct mm_struct *mm)
 			 * exception when invoking the EFI run-time services.
 			 */
 			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
 			 */
-			uaccess_ttbr0_disable();
 			update_saved_ttbr0(current, current->active_mm);
 		}
 	}
diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c
index d01ae156bb63..5d188c6c44d7 100644
--- a/arch/arm64/kernel/efi.c
+++ b/arch/arm64/kernel/efi.c
@@ -177,6 +177,8 @@ bool arch_efi_call_virt_setup(void)
 		return false;
 
 	efi_virtmap_load();
+	uaccess_ttbr0_enable();
+	post_ttbr_update_workaround();
 	__efi_fpsimd_begin();
 	return true;
 }
@@ -185,6 +187,7 @@ void arch_efi_call_virt_teardown(void)
 {
 	__efi_fpsimd_end();
 	efi_virtmap_unload();
+	uaccess_ttbr0_disable();
 	up(&efi_rt_lock);
 }
 
-- 
2.49.0.1101.gccaa498523-goog