From: james.morse@arm•com (James Morse)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v2 04/13] arm64: decouple early fixmap init from linear mapping
Date: Wed, 06 Jan 2016 16:35:34 +0000 [thread overview]
Message-ID: <568D4256.5030700@arm.com> (raw)
In-Reply-To: <1451489172-17420-5-git-send-email-ard.biesheuvel@linaro.org>
Hi Ard!
On 30/12/15 15:26, Ard Biesheuvel wrote:
> Since the early fixmap page tables are populated using pages that are
> part of the static footprint of the kernel, they are covered by the
> initial kernel mapping, and we can refer to them without using __va/__pa
> translations, which are tied to the linear mapping.
>
> Instead, let's introduce __phys_to_kimg, which will be tied to the kernel
> virtual mapping, regardless of whether or not it intersects with the linear
> mapping. This will allow us to move the kernel out of the linear mapping in
> a subsequent patch.
>
I gave your arm64-kaslr-v2 branch a go on juno r1, currently with
ARM64_RELOCATABLE_KERNEL=n, to find it didn't boot.
git bisect pointed to this patch. From the debugger it looks like
rubbish is ending up the page tables after early_fixmap_init(), printing
bits of bm_pmd and friends shows these aren't zeroed.
I think this is because the section(".pgdir") is dragging these outside
the __bss_start/__bss_stop range that is zeroed in head.S:__mmap_switched().
The following inelegant patch fixes this problem for me:
----------------------------%<----------------------------
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index a78fc5a882da..15fc9712ddc1 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -559,6 +559,7 @@ void __init early_fixmap_init(void)
if (pgd_none(*pgd)) {
static pud_t bm_pud[PTRS_PER_PUD] __pgdir;
+ memset(bm_pud, 0, sizeof(bm_pud));
pgd_populate(&init_mm, pgd, bm_pud);
memblock_reserve(__pa(bm_pud), sizeof(bm_pud));
}
@@ -570,6 +571,7 @@ void __init early_fixmap_init(void)
if (pud_none(*pud)) {
static pmd_t bm_pmd[PTRS_PER_PMD] __pgdir;
+ memset(bm_pmd, 0, sizeof(bm_pmd));
pud_populate(&init_mm, pud, bm_pmd);
memblock_reserve(__pa(bm_pmd), sizeof(bm_pmd));
}
@@ -580,6 +582,7 @@ void __init early_fixmap_init(void)
if (pmd_none(*pmd)) {
static pte_t bm_pte[PTRS_PER_PTE] __pgdir;
+ memset(bm_pte, 0, sizeof(bm_pte));
pmd_populate_kernel(&init_mm, pmd, bm_pte);
memblock_reserve(__pa(bm_pte), sizeof(bm_pte));
}
----------------------------%<----------------------------
I'm sure there is a better way!
Thanks,
James
next prev parent reply other threads:[~2016-01-06 16:35 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-30 15:25 [PATCH v2 00/13] arm64: implement support for KASLR Ard Biesheuvel
2015-12-30 15:26 ` [PATCH v2 01/13] of/fdt: make memblock minimum physical address arch configurable Ard Biesheuvel
2015-12-30 15:26 ` [PATCH v2 02/13] arm64: introduce KIMAGE_VADDR as the virtual base of the kernel region Ard Biesheuvel
2016-01-05 14:36 ` Christoffer Dall
2016-01-05 14:46 ` Mark Rutland
2016-01-05 14:58 ` Christoffer Dall
2015-12-30 15:26 ` [PATCH v2 03/13] arm64: use more granular reservations for static page table allocations Ard Biesheuvel
2016-01-07 13:55 ` Mark Rutland
2016-01-07 14:02 ` Ard Biesheuvel
2016-01-07 14:25 ` Mark Rutland
2015-12-30 15:26 ` [PATCH v2 04/13] arm64: decouple early fixmap init from linear mapping Ard Biesheuvel
2016-01-06 16:35 ` James Morse [this message]
2016-01-06 16:42 ` Ard Biesheuvel
2016-01-08 12:00 ` Catalin Marinas
2016-01-08 12:05 ` Ard Biesheuvel
2015-12-30 15:26 ` [PATCH v2 05/13] arm64: kvm: deal with kernel symbols outside of " Ard Biesheuvel
2016-01-04 10:08 ` Marc Zyngier
2016-01-04 10:31 ` Ard Biesheuvel
2016-01-04 11:02 ` Marc Zyngier
2016-01-05 14:41 ` Christoffer Dall
2016-01-05 14:51 ` Ard Biesheuvel
2016-01-05 14:56 ` Christoffer Dall
2015-12-30 15:26 ` [PATCH v2 06/13] arm64: move kernel image to base of vmalloc area Ard Biesheuvel
2015-12-30 15:26 ` [PATCH v2 07/13] arm64: add support for module PLTs Ard Biesheuvel
2015-12-30 15:26 ` [PATCH v2 08/13] arm64: use relative references in exception tables Ard Biesheuvel
2015-12-30 15:26 ` [PATCH v2 09/13] arm64: avoid R_AARCH64_ABS64 relocations for Image header fields Ard Biesheuvel
2015-12-30 15:26 ` [PATCH v2 10/13] arm64: avoid dynamic relocations in early boot code Ard Biesheuvel
2015-12-30 15:26 ` [PATCH v2 11/13] arm64: allow kernel Image to be loaded anywhere in physical memory Ard Biesheuvel
2016-01-08 11:26 ` Mark Rutland
2016-01-08 11:34 ` Ard Biesheuvel
2016-01-08 11:43 ` Mark Rutland
2016-01-08 15:27 ` Catalin Marinas
2016-01-08 15:30 ` Ard Biesheuvel
2016-01-08 15:36 ` Mark Rutland
2016-01-08 15:48 ` Catalin Marinas
2016-01-08 16:14 ` Mark Rutland
2015-12-30 15:26 ` [PATCH v2 12/13] arm64: add support for relocatable kernel Ard Biesheuvel
2016-01-05 19:51 ` Kees Cook
2016-01-06 7:51 ` Ard Biesheuvel
2016-01-08 10:17 ` James Morse
2016-01-08 10:25 ` Ard Biesheuvel
2016-01-08 12:36 ` Mark Rutland
2016-01-08 12:38 ` Ard Biesheuvel
2016-01-08 12:40 ` Mark Rutland
2016-01-08 12:41 ` [PATCH] arm64: split elf relocs into a separate header Mark Rutland
2016-01-08 15:59 ` Will Deacon
2016-01-12 11:55 ` Ard Biesheuvel
2015-12-30 15:26 ` [PATCH v2 13/13] arm64: efi: invoke EFI_RNG_PROTOCOL to supply KASLR randomness Ard Biesheuvel
2016-01-05 19:53 ` Kees Cook
2016-01-06 7:51 ` Ard Biesheuvel
2016-01-07 18:46 ` Mark Rutland
2016-01-07 19:07 ` Kees Cook
2016-01-05 20:08 ` [PATCH v2 00/13] arm64: implement support for KASLR Kees Cook
2016-01-05 21:24 ` Ard Biesheuvel
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