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| author | Linus Walleij <linusw@kernel.org> | 2026-06-30 18:05:56 +0100 |
|---|---|---|
| committer | Russell King <rmk+kernel@armlinux.org.uk> | 2026-08-05 16:48:11 +0100 |
| commit | bb3b2cfeb206f5b10b859e134651b54120e3f530 (patch) | |
| tree | 6717fcea088ba5c5f15002a48101fa2537135bf2 /arch/arm/kernel | |
| parent | 055a410f7c9f7efa2b5524ad837d6cca78dd0b81 (diff) | |
| download | linux-next-bb3b2cfeb206f5b10b859e134651b54120e3f530.tar.gz linux-next-bb3b2cfeb206f5b10b859e134651b54120e3f530.zip | |
ARM: 9480/1: entry: expand comment in __switch_to
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>
Diffstat (limited to 'arch/arm/kernel')
| -rw-r--r-- | arch/arm/kernel/entry-armv.S | 13 |
1 files changed, 10 insertions, 3 deletions
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S index ef6a657c8d13..b7faefe5bce7 100644 --- a/arch/arm/kernel/entry-armv.S +++ b/arch/arm/kernel/entry-armv.S @@ -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 |