diff options
| -rw-r--r-- | arch/arm/kernel/hibernate.c | 10 | ||||
| -rw-r--r-- | arch/arm/mm/idmap.c | 12 |
2 files changed, 22 insertions, 0 deletions
diff --git a/arch/arm/kernel/hibernate.c b/arch/arm/kernel/hibernate.c index 38a90a3d12b2..231a76af09a0 100644 --- a/arch/arm/kernel/hibernate.c +++ b/arch/arm/kernel/hibernate.c @@ -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); diff --git a/arch/arm/mm/idmap.c b/arch/arm/mm/idmap.c index 4a833e89782a..70403e968d2a 100644 --- a/arch/arm/mm/idmap.c +++ b/arch/arm/mm/idmap.c @@ -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(); |