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From: Ard Biesheuvel <ardb@kernel.org>
To: linux-arm-kernel@lists.infradead.org
Cc: Ard Biesheuvel <ardb@kernel.org>, Marc Zyngier <maz@kernel.org>,
	Will Deacon <will@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Kees Cook <keescook@chromium.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Mark Brown <broonie@kernel.org>,
	Anshuman Khandual <anshuman.khandual@arm.com>
Subject: [PATCH v5 08/21] arm64: kernel: drop unnecessary PoC cache clean+invalidate
Date: Fri, 24 Jun 2022 17:06:38 +0200	[thread overview]
Message-ID: <20220624150651.1358849-9-ardb@kernel.org> (raw)
In-Reply-To: <20220624150651.1358849-1-ardb@kernel.org>

Some early boot code runs before the virtual placement of the kernel is
finalized, and we used to go back to the very start and recreate the ID
map along with the page tables describing the virtual kernel mapping,
and this involved setting some global variables with the caches off.

In order to ensure that global state created by the KASLR code is not
corrupted by the cache invalidation that occurs in that case, we needed
to clean those global variables to the PoC explicitly.

This is no longer needed now that the ID map is created only once (and
the associated global variable updates are no longer repeated). So drop
the cache maintenance that is no longer necessary.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
---
 arch/arm64/kernel/kaslr.c | 11 -----------
 1 file changed, 11 deletions(-)

diff --git a/arch/arm64/kernel/kaslr.c b/arch/arm64/kernel/kaslr.c
index 418b2bba1521..d5542666182f 100644
--- a/arch/arm64/kernel/kaslr.c
+++ b/arch/arm64/kernel/kaslr.c
@@ -13,7 +13,6 @@
 #include <linux/pgtable.h>
 #include <linux/random.h>
 
-#include <asm/cacheflush.h>
 #include <asm/fixmap.h>
 #include <asm/kernel-pgtable.h>
 #include <asm/memory.h>
@@ -72,9 +71,6 @@ u64 __init kaslr_early_init(void)
 	 * we end up running with module randomization disabled.
 	 */
 	module_alloc_base = (u64)_etext - MODULES_VSIZE;
-	dcache_clean_inval_poc((unsigned long)&module_alloc_base,
-			    (unsigned long)&module_alloc_base +
-				    sizeof(module_alloc_base));
 
 	/*
 	 * Try to map the FDT early. If this fails, we simply bail,
@@ -174,13 +170,6 @@ u64 __init kaslr_early_init(void)
 	module_alloc_base += (module_range * (seed & ((1 << 21) - 1))) >> 21;
 	module_alloc_base &= PAGE_MASK;
 
-	dcache_clean_inval_poc((unsigned long)&module_alloc_base,
-			    (unsigned long)&module_alloc_base +
-				    sizeof(module_alloc_base));
-	dcache_clean_inval_poc((unsigned long)&memstart_offset_seed,
-			    (unsigned long)&memstart_offset_seed +
-				    sizeof(memstart_offset_seed));
-
 	return offset;
 }
 
-- 
2.35.1


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  parent reply	other threads:[~2022-06-24 15:10 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-06-24 15:06 [PATCH v5 00/21] arm64: refactor boot flow Ard Biesheuvel
2022-06-24 15:06 ` [PATCH v5 01/21] arm64: head: move kimage_vaddr variable into C file Ard Biesheuvel
2022-06-26  9:22   ` Mark Rutland
2022-06-24 15:06 ` [PATCH v5 02/21] arm64: mm: make vabits_actual a build time constant if possible Ard Biesheuvel
2022-06-26  9:31   ` Mark Rutland
2022-06-24 15:06 ` [PATCH v5 03/21] arm64: head: move assignment of idmap_t0sz to C code Ard Biesheuvel
2022-06-26  9:36   ` Mark Rutland
2022-06-24 15:06 ` [PATCH v5 04/21] arm64: head: drop idmap_ptrs_per_pgd Ard Biesheuvel
2022-06-26  9:37   ` Mark Rutland
2022-06-24 15:06 ` [PATCH v5 05/21] arm64: head: simplify page table mapping macros (slightly) Ard Biesheuvel
2022-06-26 10:07   ` Mark Rutland
2022-06-24 15:06 ` [PATCH v5 06/21] arm64: head: switch to map_memory macro for the extended ID map Ard Biesheuvel
2022-06-24 15:06 ` [PATCH v5 07/21] arm64: head: split off idmap creation code Ard Biesheuvel
2022-06-24 15:06 ` Ard Biesheuvel [this message]
2022-06-24 15:06 ` [PATCH v5 09/21] arm64: head: pass ID map root table address to __enable_mmu() Ard Biesheuvel
2022-06-24 15:06 ` [PATCH v5 10/21] arm64: mm: provide idmap pointer to cpu_replace_ttbr1() Ard Biesheuvel
2022-06-24 15:06 ` [PATCH v5 11/21] arm64: head: add helper function to remap regions in early page tables Ard Biesheuvel
2022-06-24 15:06 ` [PATCH v5 12/21] arm64: head: cover entire kernel image in initial ID map Ard Biesheuvel
2022-06-24 15:06 ` [PATCH v5 13/21] arm64: head: use relative references to the RELA and RELR tables Ard Biesheuvel
2022-06-24 15:06 ` [PATCH v5 14/21] arm64: head: create a temporary FDT mapping in the initial ID map Ard Biesheuvel
2022-06-24 15:06 ` [PATCH v5 15/21] arm64: idreg-override: use early FDT mapping in " Ard Biesheuvel
2022-07-11 15:39   ` Mark Rutland
2022-07-12 17:03     ` Ard Biesheuvel
2022-07-13 14:09       ` Mark Rutland
2022-06-24 15:06 ` [PATCH v5 16/21] arm64: head: factor out TTBR1 assignment into a macro Ard Biesheuvel
2022-06-24 15:06 ` [PATCH v5 17/21] arm64: head: populate kernel page tables with MMU and caches on Ard Biesheuvel
2022-06-24 15:06 ` [PATCH v5 18/21] arm64: head: record CPU boot mode after enabling the MMU Ard Biesheuvel
2022-06-24 15:06 ` [PATCH v5 19/21] arm64: kaslr: defer initialization to initcall where permitted Ard Biesheuvel
2022-06-24 15:06 ` [PATCH v5 20/21] arm64: head: avoid relocating the kernel twice for KASLR Ard Biesheuvel
2022-06-24 15:06 ` [PATCH v5 21/21] arm64: setup: drop early FDT pointer helpers Ard Biesheuvel
2022-06-24 17:13 ` [PATCH v5 00/21] arm64: refactor boot flow Will Deacon

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