proxmox-mirrors/mirror_ubuntu-kernels
1
0
Fork 0
mirror of https://git.proxmox.com/git/mirror_ubuntu-kernels.git synced 2025-12-07 18:28:26 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

arm64: head: Clear BSS and the kernel page tables in one go

Browse Source 
We will move the CPU feature overrides into BSS in a subsequent patch,
and this requires that BSS is zeroed before the feature override
detection code runs. So let's map BSS read-write in the ID map, and zero
it via this mapping.

Since the kernel page tables are right next to it, and also zeroed via
the ID map, let's drop the separate clear_page_tables() function, and
just zero everything in one go.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20240214122845.2033971-51-ardb+git@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Ard Biesheuvel 2024-02-14 13:28:52 +01:00 committed by Catalin Marinas
parent 9c4cd2a7d1
commit aa99aad798
2 changed files with 14 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

33
arch/arm64/kernel/head.S
View File

@ -177,17 +177,6 @@ SYM_CODE_START_LOCAL(preserve_boot_args)
ret
SYM_CODE_END(preserve_boot_args)
SYM_FUNC_START_LOCAL(clear_page_tables)
/*
* Clear the init page tables.
*/
adrp x0, init_pg_dir
adrp x1, init_pg_end
sub x2, x1, x0
mov x1, xzr
b __pi_memset // tail call
SYM_FUNC_END(clear_page_tables)
/*
* Macro to populate page table entries, these entries can be pointers to the next level
* or last level entries pointing to physical memory.
@ -386,9 +375,9 @@ SYM_FUNC_START_LOCAL(create_idmap)
map_memory x0, x1, x3, x6, x7, x3, IDMAP_PGD_ORDER, x10, x11, x12, x13, x14, EXTRA_SHIFT
/* Remap the kernel page tables r/w in the ID map */
/* Remap BSS and the kernel page tables r/w in the ID map */
adrp x1, _text
adrp x2, init_pg_dir
adrp x2, __bss_start
adrp x3, _end
bic x4, x2, #SWAPPER_BLOCK_SIZE - 1
mov_q x5, SWAPPER_RW_MMUFLAGS
@ -489,14 +478,6 @@ SYM_FUNC_START_LOCAL(__primary_switched)
mov x0, x20
bl set_cpu_boot_mode_flag
// Clear BSS
adr_l x0, __bss_start
mov x1, xzr
adr_l x2, __bss_stop
sub x2, x2, x0
bl __pi_memset
dsb ishst // Make zero page visible to PTW
#if VA_BITS > 48
adr_l x8, vabits_actual // Set this early so KASAN early init
str x25, [x8] // ... observes the correct value
@ -782,6 +763,15 @@ SYM_FUNC_START_LOCAL(__primary_switch)
adrp x1, reserved_pg_dir
adrp x2, init_idmap_pg_dir
bl __enable_mmu
// Clear BSS
adrp x0, __bss_start
mov x1, xzr
adrp x2, init_pg_end
sub x2, x2, x0
bl __pi_memset
dsb ishst // Make zero page visible to PTW
#ifdef CONFIG_RELOCATABLE
adrp x23, KERNEL_START
and x23, x23, MIN_KIMG_ALIGN - 1
@ -796,7 +786,6 @@ SYM_FUNC_START_LOCAL(__primary_switch)
orr x23, x23, x0 // record kernel offset
#endif
#endif
bl clear_page_tables
bl create_kernel_mapping
adrp x1, init_pg_dir

3
arch/arm64/kernel/vmlinux.lds.S
View File

@ -311,12 +311,15 @@ SECTIONS
__pecoff_data_rawsize = ABSOLUTE(. - __initdata_begin);
_edata = .;
/* start of zero-init region */
BSS_SECTION(SBSS_ALIGN, 0, 0)
. = ALIGN(PAGE_SIZE);
init_pg_dir = .;
. += INIT_DIR_SIZE;
init_pg_end = .;
/* end of zero-init region */
#ifdef CONFIG_RELOCATABLE
. += SZ_4K; /* stack for the early relocation code */
early_init_stack = .;