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ARM fixes for 7.1

Browse source 
Three fixes:
 - Avoid KASAN instrumentation of half-word IO
 - Use a byte load for KASAN shadow stack
 - Fix kexec and hibernation with PAN
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rmk/linux

Pull ARM fixes from Russell King:

 - Avoid KASAN instrumentation of half-word IO

 - Use a byte load for KASAN shadow stack

 - Fix kexec and hibernation with PAN

* tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rmk/linux:
  ARM: 9476/1: mm: fix kexec and hibernation with CONFIG_CPU_TTBR0_PAN
  ARM: 9475/1: entry: use byte load for KASAN VMAP stack shadow
  ARM: 9474/1: io: avoid KASAN instrumentation of raw halfword I/O
This commit is contained in:
Linus Torvalds 2026-06-14 15:37:39 +01:00
commit 4242809533
4 changed files with 36 additions and 3 deletions
Download patch file Download diff file Expand all files Collapse all files

15
arch/arm/include/asm/io.h
View file

@ -56,8 +56,19 @@ void __raw_readsl(const volatile void __iomem *addr, void *data, int longlen);
* the bus. Rather than special-case the machine, just let the compiler
* generate the access for CPUs prior to ARMv6.
*/
#define __raw_readw(a) (__chk_io_ptr(a), *(volatile unsigned short __force *)(a))
#define __raw_writew(v,a) ((void)(__chk_io_ptr(a), *(volatile unsigned short __force *)(a) = (v)))
#define __raw_writew __raw_writew
static __no_kasan_or_inline void __raw_writew(u16 val, volatile void __iomem *addr)
{
__chk_io_ptr(addr);
*(volatile unsigned short __force *)addr = val;
}
#define __raw_readw __raw_readw
static __no_kasan_or_inline u16 __raw_readw(const volatile void __iomem *addr)
{
__chk_io_ptr(addr);
return *(const volatile unsigned short __force *)addr;
}
#else
/*
* When running under a hypervisor, we want to avoid I/O accesses with

2
arch/arm/kernel/entry-armv.S
View file

@ -567,7 +567,7 @@ ENTRY(__switch_to)
@ are using KASAN
mov_l r2, KASAN_SHADOW_OFFSET
add r2, r2, ip, lsr #KASAN_SHADOW_SCALE_SHIFT
ldr r2, [r2]
ldrb r2, [r2]
#endif
#endif

10
arch/arm/kernel/hibernate.c
View file

@ -21,6 +21,7 @@
#include <asm/suspend.h>
#include <asm/page.h>
#include <asm/sections.h>
#include <asm/uaccess.h>
#include "reboot.h"
int pfn_is_nosave(unsigned long pfn)
@ -82,6 +83,15 @@ static void notrace arch_restore_image(void *unused)
{
struct pbe *pbe;
/*
* With CONFIG_CPU_TTBR0_PAN enabled, TTBCR.EPD0 is set to block
* TTBR0 page-table walks. The identity mapping used here lives at
* low (user-space) virtual addresses and is only reachable via
* TTBR0, so re-enable those walks before switching page tables.
* On non-PAN kernels this is a no-op.
*/
if (IS_ENABLED(CONFIG_CPU_TTBR0_PAN))
uaccess_save_and_enable();
cpu_switch_mm(idmap_pgd, &init_mm);
for (pbe = restore_pblist; pbe; pbe = pbe->next)
copy_page(pbe->orig_address, pbe->address);

12
arch/arm/mm/idmap.c
View file

@ -11,6 +11,7 @@
#include <asm/pgalloc.h>
#include <asm/sections.h>
#include <asm/system_info.h>
#include <asm/uaccess.h>
/*
* Note: accesses outside of the kernel image and the identity map area
@ -133,6 +134,17 @@ early_initcall(init_static_idmap);
*/
void setup_mm_for_reboot(void)
{
/*
* With CONFIG_CPU_TTBR0_PAN enabled, TTBCR.EPD0 is set whenever
* user-space access is disabled in order to block TTBR0 page-table
* walks. The identity mapping lives at low (user-space) virtual
* addresses and can only be reached via TTBR0, so we must re-enable
* those walks before switching page tables. On non-PAN kernels this
* is a no-op.
*/
if (IS_ENABLED(CONFIG_CPU_TTBR0_PAN))
uaccess_save_and_enable();
/* Switch to the identity mapping. */
cpu_switch_mm(idmap_pgd, &init_mm);
local_flush_bp_all();