github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-09-13 15:40:03 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

ARM: 9480/1: entry: expand comment in __switch_to

Browse Source 
As per discussion between the developers in the mail thread
linked, expand the comment in __switch_to so that readers
of the code understand what is going on.

Suggested-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Linus Walleij <linusw@kernel.org>>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
This commit is contained in:
Linus Walleij 2026-06-30 18:05:56 +01:00 committed by Russell King
parent 055a410f7c
commit bb3b2cfeb2
1 changed files with 10 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
arch/arm/kernel/entry-armv.S
View File

@ -557,9 +557,16 @@ ENTRY(__switch_to)
ldmia r4, {r4 - sl, fp, ip, lr} @ Load all regs saved previously
#ifdef CONFIG_VMAP_STACK
@
@ Do a dummy read from the new stack while running from the old one so
@ that we can rely on do_translation_fault() to fix up any stale PMD
@ entries covering the vmalloc region.
@ For a non-lazy mm switch, check_vmalloc_seq() has ensured that
@ that the active mm's page tables have mappings for the prev
@ task's stack and the next task's stack.
@
@ For a lazy mm switch the active mm's page tables have mappings
@ for the prev task's stack but might not have mappings for the
@ new task's stack. Do a dummy read from the new stack while
@ running from the old stack so that we can rely on
@ do_translation_fault() to populate missing PMD entries covering the
@ new task's stack in the old task's page tables.
@
ldr r2, [ip]
#ifdef CONFIG_KASAN_VMALLOC