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 14/21] arm64: head: create a temporary FDT mapping in the initial ID map
Date: Fri, 24 Jun 2022 17:06:44 +0200 [thread overview]
Message-ID: <20220624150651.1358849-15-ardb@kernel.org> (raw)
In-Reply-To: <20220624150651.1358849-1-ardb@kernel.org>
We need to access the DT very early to get at the command line and the
KASLR seed, which currently means we rely on some hacks to call into the
kernel before really calling into the kernel, which is undesirable.
So instead, let's create a mapping for the FDT in the initial ID map,
which is feasible now that it has been extended to cover more than a
single page or block, and can be updated in place to remap other output
addresses.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
arch/arm64/include/asm/kernel-pgtable.h | 6 ++++--
arch/arm64/kernel/head.S | 14 +++++++++++++-
2 files changed, 17 insertions(+), 3 deletions(-)
diff --git a/arch/arm64/include/asm/kernel-pgtable.h b/arch/arm64/include/asm/kernel-pgtable.h
index 5395e5a04f35..02e59fa8f293 100644
--- a/arch/arm64/include/asm/kernel-pgtable.h
+++ b/arch/arm64/include/asm/kernel-pgtable.h
@@ -8,6 +8,7 @@
#ifndef __ASM_KERNEL_PGTABLE_H
#define __ASM_KERNEL_PGTABLE_H
+#include <asm/boot.h>
#include <asm/pgtable-hwdef.h>
#include <asm/sparsemem.h>
@@ -88,10 +89,11 @@
/* the initial ID map may need two extra pages if it needs to be extended */
#if VA_BITS < 48
-#define INIT_IDMAP_DIR_SIZE (INIT_DIR_SIZE + (2 * PAGE_SIZE))
+#define INIT_IDMAP_DIR_SIZE ((INIT_IDMAP_DIR_PAGES + 2) * PAGE_SIZE)
#else
-#define INIT_IDMAP_DIR_SIZE INIT_DIR_SIZE
+#define INIT_IDMAP_DIR_SIZE (INIT_IDMAP_DIR_PAGES * PAGE_SIZE)
#endif
+#define INIT_IDMAP_DIR_PAGES EARLY_PAGES(KIMAGE_VADDR, _end + MAX_FDT_SIZE + SWAPPER_BLOCK_SIZE)
/* Initial memory map size */
#if ARM64_KERNEL_USES_PMD_MAPS
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index f1497f7b4da0..8283ff848328 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -83,6 +83,7 @@
*
* Register Scope Purpose
* x21 primary_entry() .. start_kernel() FDT pointer passed at boot in x0
+ * x22 create_idmap() .. start_kernel() ID map VA of the DT blob
* x23 primary_entry() .. start_kernel() physical misalignment/KASLR offset
* x28 clear_page_tables() callee preserved temp register
* x19/x20 __primary_switch() callee preserved temp registers
@@ -348,7 +349,7 @@ SYM_FUNC_START_LOCAL(create_idmap)
#endif
adrp x0, init_idmap_pg_dir
adrp x3, _text
- adrp x6, _end
+ adrp x6, _end + MAX_FDT_SIZE + SWAPPER_BLOCK_SIZE
mov x7, SWAPPER_RX_MMUFLAGS
map_memory x0, x1, x3, x6, x7, x3, IDMAP_PGD_ORDER, x10, x11, x12, x13, x14, EXTRA_SHIFT
@@ -362,6 +363,17 @@ SYM_FUNC_START_LOCAL(create_idmap)
mov x6, #SWAPPER_BLOCK_SHIFT
bl remap_region
+ /* Remap the FDT after the kernel image */
+ adrp x1, _text
+ adrp x22, _end + SWAPPER_BLOCK_SIZE
+ bic x2, x22, #SWAPPER_BLOCK_SIZE - 1
+ bfi x22, x21, #0, #SWAPPER_BLOCK_SHIFT // remapped FDT address
+ add x3, x2, #MAX_FDT_SIZE + SWAPPER_BLOCK_SIZE
+ bic x4, x21, #SWAPPER_BLOCK_SIZE - 1
+ mov x5, SWAPPER_RW_MMUFLAGS
+ mov x6, #SWAPPER_BLOCK_SHIFT
+ bl remap_region
+
/*
* Since the page tables have been populated with non-cacheable
* accesses (MMU disabled), invalidate those tables again to
--
2.35.1
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next prev parent reply other threads:[~2022-06-24 15:13 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 ` [PATCH v5 08/21] arm64: kernel: drop unnecessary PoC cache clean+invalidate Ard Biesheuvel
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 ` Ard Biesheuvel [this message]
2022-06-24 15:06 ` [PATCH v5 15/21] arm64: idreg-override: use early FDT mapping in ID map 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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