From: Ard Biesheuvel <ardb@kernel.org>
To: linux-arm-kernel@lists.infradead.org
Cc: linux-efi@vger.kernel.org, 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>
Subject: [PATCH v3 04/30] arm64: head: drop idmap_ptrs_per_pgd
Date: Mon, 11 Apr 2022 11:47:58 +0200 [thread overview]
Message-ID: <20220411094824.4176877-5-ardb@kernel.org> (raw)
In-Reply-To: <20220411094824.4176877-1-ardb@kernel.org>
The assignment of idmap_ptrs_per_pgd lacks any cache invalidation, even
though it is updated with the MMU and caches disabled. However, we never
bother to read the value again except in the very next instruction, and
so we can just drop the variable entirely.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
arch/arm64/include/asm/mmu_context.h | 1 -
arch/arm64/kernel/head.S | 7 +++----
arch/arm64/mm/mmu.c | 1 -
3 files changed, 3 insertions(+), 6 deletions(-)
diff --git a/arch/arm64/include/asm/mmu_context.h b/arch/arm64/include/asm/mmu_context.h
index 6ac0086ebb1a..7b387c3b312a 100644
--- a/arch/arm64/include/asm/mmu_context.h
+++ b/arch/arm64/include/asm/mmu_context.h
@@ -61,7 +61,6 @@ static inline void cpu_switch_mm(pgd_t *pgd, struct mm_struct *mm)
* physical memory, in which case it will be smaller.
*/
extern int idmap_t0sz;
-extern u64 idmap_ptrs_per_pgd;
/*
* Ensure TCR.T0SZ is set to the provided value.
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index 7f361bc72d12..53126a35d73c 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -300,6 +300,7 @@ SYM_FUNC_START_LOCAL(__create_page_tables)
* range in that case, and configure an additional translation level
* if needed.
*/
+ mov x4, #PTRS_PER_PGD
idmap_get_t0sz x5
cmp x5, TCR_T0SZ(VA_BITS_MIN) // default T0SZ small enough?
b.ge 1f // .. then skip VA range extension
@@ -319,18 +320,16 @@ SYM_FUNC_START_LOCAL(__create_page_tables)
#error "Mismatch between VA_BITS and page size/number of translation levels"
#endif
- mov x4, EXTRA_PTRS
- create_table_entry x0, x3, EXTRA_SHIFT, x4, x5, x6
+ mov x2, EXTRA_PTRS
+ create_table_entry x0, x3, EXTRA_SHIFT, x2, x5, x6
#else
/*
* If VA_BITS == 48, we don't have to configure an additional
* translation level, but the top-level table has more entries.
*/
mov x4, #1 << (PHYS_MASK_SHIFT - PGDIR_SHIFT)
- str_l x4, idmap_ptrs_per_pgd, x5
#endif
1:
- ldr_l x4, idmap_ptrs_per_pgd
adr_l x6, __idmap_text_end // __pa(__idmap_text_end)
map_memory x0, x1, x3, x6, x7, x3, x4, x10, x11, x12, x13, x14
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index a6732da20874..0618ece00b7e 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -44,7 +44,6 @@
#define NO_EXEC_MAPPINGS BIT(2) /* assumes FEAT_HPDS is not used */
int idmap_t0sz __ro_after_init;
-u64 idmap_ptrs_per_pgd = PTRS_PER_PGD;
#if VA_BITS > 48
u64 vabits_actual __ro_after_init = VA_BITS_MIN;
--
2.30.2
next prev parent reply other threads:[~2022-04-11 9:49 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-11 9:47 [PATCH v3 00/30] arm64: support WXN and entry with MMU enabled Ard Biesheuvel
2022-04-11 9:47 ` [PATCH v3 01/30] arm64: head: move kimage_vaddr variable into C file Ard Biesheuvel
2022-04-11 9:47 ` [PATCH v3 02/30] arm64: mm: make vabits_actual a build time constant if possible Ard Biesheuvel
2022-04-11 9:47 ` [PATCH v3 03/30] arm64: head: move assignment of idmap_t0sz to C code Ard Biesheuvel
2022-04-11 9:47 ` Ard Biesheuvel [this message]
2022-04-11 9:47 ` [PATCH v3 05/30] arm64: head: simplify page table mapping macros (slightly) Ard Biesheuvel
2022-04-11 9:48 ` [PATCH v3 06/30] arm64: head: switch to map_memory macro for the extended ID map Ard Biesheuvel
2022-04-11 9:48 ` [PATCH v3 07/30] arm64: head: split off idmap creation code Ard Biesheuvel
2022-04-11 9:48 ` [PATCH v3 08/30] arm64: kernel: drop unnecessary PoC cache clean+invalidate Ard Biesheuvel
2022-04-11 9:48 ` [PATCH v3 09/30] arm64: head: pass ID map root table address to __enable_mmu() Ard Biesheuvel
2022-04-11 9:48 ` [PATCH v3 10/30] arm64: mm: provide idmap pointer to cpu_replace_ttbr1() Ard Biesheuvel
2022-04-11 9:48 ` [PATCH v3 11/30] arm64: head: add helper function to remap regions in early page tables Ard Biesheuvel
2022-04-11 9:48 ` [PATCH v3 12/30] arm64: head: cover entire kernel image in initial ID map Ard Biesheuvel
2022-04-11 9:48 ` [PATCH v3 13/30] arm64: head: use relative references to the RELA and RELR tables Ard Biesheuvel
2022-04-11 9:48 ` [PATCH v3 14/30] arm64: head: create a temporary FDT mapping in the initial ID map Ard Biesheuvel
2022-04-11 9:48 ` [PATCH v3 15/30] arm64: idreg-override: use early FDT mapping in " Ard Biesheuvel
2022-04-11 9:48 ` [PATCH v3 16/30] arm64: head: factor out TTBR1 assignment into a macro Ard Biesheuvel
2022-04-11 9:48 ` [PATCH v3 17/30] arm64: head: populate kernel page tables with MMU and caches on Ard Biesheuvel
2022-04-11 9:48 ` [PATCH v3 18/30] arm64: head: record CPU boot mode after enabling the MMU Ard Biesheuvel
2022-04-11 9:48 ` [PATCH v3 19/30] arm64: kaslr: deal with init called with VA randomization enabled Ard Biesheuvel
2022-04-11 9:48 ` [PATCH v3 20/30] arm64: head: relocate kernel only a single time if KASLR is enabled Ard Biesheuvel
2022-04-11 9:48 ` [PATCH v3 21/30] arm64: head: remap the kernel text/inittext region read-only Ard Biesheuvel
2022-04-11 9:48 ` [PATCH v3 22/30] arm64: setup: drop early FDT pointer helpers Ard Biesheuvel
2022-04-11 9:48 ` [PATCH v3 23/30] arm64: mm: move ro_after_init section into the data segment Ard Biesheuvel
2022-04-11 9:48 ` [PATCH v3 24/30] arm64: mm: add support for WXN memory translation attribute Ard Biesheuvel
2022-04-11 9:48 ` [PATCH v3 25/30] arm64: head: record the MMU state at primary entry Ard Biesheuvel
2022-04-11 9:48 ` [PATCH v3 26/30] arm64: head: avoid cache invalidation when entering with the MMU on Ard Biesheuvel
2022-04-11 9:48 ` [PATCH v3 27/30] arm64: head: clean the ID map page to the PoC Ard Biesheuvel
2022-04-11 9:48 ` [PATCH v3 28/30] efi: libstub: pass image handle to handle_kernel_image() Ard Biesheuvel
2022-04-11 9:48 ` [PATCH v3 29/30] efi/arm64: libstub: run image in place if randomized by the loader Ard Biesheuvel
2022-04-11 9:48 ` [PATCH v3 30/30] arm64: efi/libstub: enter with the MMU on if executing in place Ard Biesheuvel
2022-04-12 16:59 ` [PATCH v3 00/30] arm64: support WXN and entry with MMU enabled Kees Cook
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