From: Ard Biesheuvel <ardb@kernel.org>
To: linux-arm-kernel@lists.infradead.org
Cc: linux-efi@vger.kernel.org, keescook@chromium.org,
Ard Biesheuvel <ardb@kernel.org>, Will Deacon <will@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Marc Zyngier <maz@kernel.org>,
Mark Rutland <mark.rutland@arm.com>
Subject: [PATCH v5 5/7] arm64: head: Clean the ID map and the HYP text to the PoC if needed
Date: Tue, 8 Nov 2022 19:22:02 +0100 [thread overview]
Message-ID: <20221108182204.2447664-6-ardb@kernel.org> (raw)
In-Reply-To: <20221108182204.2447664-1-ardb@kernel.org>
If we enter with the MMU and caches enabled, the bootloader may not have
performed any cache maintenance to the PoC. So clean the ID mapped page
to the PoC, to ensure that instruction and data accesses with the MMU
off see the correct data. For similar reasons, clean all the HYP text to
the PoC as well when entering at EL2 with the MMU and caches enabled.
Note that this means primary_entry() itself needs to be moved into the
ID map as well, as we will return from init_kernel_el() with the MMU and
caches off.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
arch/arm64/kernel/head.S | 31 +++++++++++++++++---
arch/arm64/kernel/sleep.S | 1 +
2 files changed, 28 insertions(+), 4 deletions(-)
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index a7c84cde67c5c652..825f1d0549661030 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -70,7 +70,7 @@
__EFI_PE_HEADER
- __INIT
+ .section ".idmap.text","awx"
/*
* The following callee saved general purpose registers are used on the
@@ -90,6 +90,17 @@ SYM_CODE_START(primary_entry)
bl record_mmu_state
bl preserve_boot_args
bl create_idmap
+
+ /*
+ * If we entered with the MMU and caches on, clean the ID mapped part
+ * of the primary boot code to the PoC so we can safely execute it with
+ * the MMU off.
+ */
+ cbz x19, 0f
+ adrp x0, __idmap_text_start
+ adr_l x1, __idmap_text_end
+ bl dcache_clean_poc
+0: mov x19, x0
bl init_kernel_el // w0=cpu_boot_mode
mov x20, x0
@@ -111,6 +122,7 @@ SYM_CODE_START(primary_entry)
b __primary_switch
SYM_CODE_END(primary_entry)
+ __INIT
SYM_CODE_START_LOCAL(record_mmu_state)
mrs x19, CurrentEL
cmp x19, #CurrentEL_EL2
@@ -505,10 +517,12 @@ SYM_FUNC_END(__primary_switched)
* Returns either BOOT_CPU_MODE_EL1 or BOOT_CPU_MODE_EL2 in x0 if
* booted in EL1 or EL2 respectively, with the top 32 bits containing
* potential context flags. These flags are *not* stored in __boot_cpu_mode.
+ *
+ * x0: whether we are being called from the primary boot path with the MMU on
*/
SYM_FUNC_START(init_kernel_el)
- mrs x0, CurrentEL
- cmp x0, #CurrentEL_EL2
+ mrs x1, CurrentEL
+ cmp x1, #CurrentEL_EL2
b.eq init_el2
SYM_INNER_LABEL(init_el1, SYM_L_LOCAL)
@@ -523,6 +537,14 @@ SYM_INNER_LABEL(init_el1, SYM_L_LOCAL)
eret
SYM_INNER_LABEL(init_el2, SYM_L_LOCAL)
+ msr elr_el2, lr
+
+ // clean all HYP code to the PoC if we booted at EL2 with the MMU on
+ cbz x0, 0f
+ adrp x0, __hyp_idmap_text_start
+ adr_l x1, __hyp_text_end
+ bl dcache_clean_poc
+0:
mov_q x0, HCR_HOST_NVHE_FLAGS
msr hcr_el2, x0
isb
@@ -556,7 +578,6 @@ SYM_INNER_LABEL(init_el2, SYM_L_LOCAL)
msr sctlr_el1, x1
mov x2, xzr
2:
- msr elr_el2, lr
mov w0, #BOOT_CPU_MODE_EL2
orr x0, x0, x2
eret
@@ -567,6 +588,7 @@ SYM_FUNC_END(init_kernel_el)
* cores are held until we're ready for them to initialise.
*/
SYM_FUNC_START(secondary_holding_pen)
+ mov x0, xzr
bl init_kernel_el // w0=cpu_boot_mode
mrs x2, mpidr_el1
mov_q x1, MPIDR_HWID_BITMASK
@@ -584,6 +606,7 @@ SYM_FUNC_END(secondary_holding_pen)
* be used where CPUs are brought online dynamically by the kernel.
*/
SYM_FUNC_START(secondary_entry)
+ mov x0, xzr
bl init_kernel_el // w0=cpu_boot_mode
b secondary_startup
SYM_FUNC_END(secondary_entry)
diff --git a/arch/arm64/kernel/sleep.S b/arch/arm64/kernel/sleep.S
index 7b7c56e048346e97..2ae7cff1953aaf87 100644
--- a/arch/arm64/kernel/sleep.S
+++ b/arch/arm64/kernel/sleep.S
@@ -99,6 +99,7 @@ SYM_FUNC_END(__cpu_suspend_enter)
.pushsection ".idmap.text", "awx"
SYM_CODE_START(cpu_resume)
+ mov x0, xzr
bl init_kernel_el
mov x19, x0 // preserve boot mode
#if VA_BITS > 48
--
2.35.1
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next prev parent reply other threads:[~2022-11-08 18:25 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-08 18:21 [PATCH v5 0/7] arm64: efi: leave MMU and caches on at boot Ard Biesheuvel
2022-11-08 18:21 ` [PATCH v5 1/7] arm64: head: Move all finalise_el2 calls to after __enable_mmu Ard Biesheuvel
2022-11-08 18:21 ` [PATCH v5 2/7] arm64: kernel: move identity map out of .text mapping Ard Biesheuvel
2022-11-08 18:22 ` [PATCH v5 3/7] arm64: head: record the MMU state at primary entry Ard Biesheuvel
2022-11-08 18:22 ` [PATCH v5 4/7] arm64: head: avoid cache invalidation when entering with the MMU on Ard Biesheuvel
2022-11-08 18:22 ` Ard Biesheuvel [this message]
2022-11-08 22:11 ` [PATCH v5 5/7] arm64: head: Clean the ID map and the HYP text to the PoC if needed Ard Biesheuvel
2022-11-08 18:22 ` [PATCH v5 6/7] arm64: lds: reduce effective minimum image alignment to 64k Ard Biesheuvel
2022-11-08 18:22 ` [PATCH v5 7/7] efi: arm64: enter with MMU and caches enabled Ard Biesheuvel
2022-11-11 17:36 ` [PATCH v5 0/7] arm64: efi: leave MMU and caches on at boot Mark Rutland
2022-11-15 11:17 ` Will Deacon
2022-11-15 11:21 ` Ard Biesheuvel
2022-11-15 11:31 ` Will Deacon
2022-11-26 14:16 ` Ard Biesheuvel
2022-11-26 14:17 ` Ard Biesheuvel
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