914f938920
When the TTBR0 PAN feature is enabled, the kernel entry points need to disable access to TTBR0_EL1. The PAN status of the interrupted context is stored as part of the saved pstate, reusing the PSR_PAN_BIT (22). Restoring access to TTBR0_PAN is done on exception return if returning to user or returning to a context where PAN was disabled. Context switching via switch_mm() must defer the update of TTBR0_EL1 until a return to user or an explicit uaccess_enable() call. Special care needs to be taken for two cases where TTBR0_EL1 is set outside the normal kernel context switch operation: EFI run-time services (via efi_set_pgd) and CPU suspend (via cpu_(un)install_idmap). Code has been added to avoid deferred TTBR0_EL1 switching as in switch_mm() and restore the reserved TTBR0_EL1 when uninstalling the special TTBR0_EL1. This patch also removes a stale comment on the switch_mm() function. Cc: Will Deacon <will.deacon@arm.com> Cc: James Morse <james.morse@arm.com> Cc: Kees Cook <keescook@chromium.org> Cc: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Change-Id: Id1198cf1cde022fad10a94f95d698fae91d742aa (cherry picked from commit d26cfd64c973b31f73091c882e07350e14fdd6c9) Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
102 lines
2.9 KiB
C
102 lines
2.9 KiB
C
#ifndef _ASM_EFI_H
|
|
#define _ASM_EFI_H
|
|
|
|
#include <asm/cpufeature.h>
|
|
#include <asm/io.h>
|
|
#include <asm/mmu_context.h>
|
|
#include <asm/neon.h>
|
|
#include <asm/tlbflush.h>
|
|
|
|
#ifdef CONFIG_EFI
|
|
extern void efi_init(void);
|
|
#else
|
|
#define efi_init()
|
|
#endif
|
|
|
|
int efi_create_mapping(struct mm_struct *mm, efi_memory_desc_t *md);
|
|
|
|
#define efi_call_virt(f, ...) \
|
|
({ \
|
|
efi_##f##_t *__f; \
|
|
efi_status_t __s; \
|
|
\
|
|
kernel_neon_begin(); \
|
|
efi_virtmap_load(); \
|
|
__f = efi.systab->runtime->f; \
|
|
__s = __f(__VA_ARGS__); \
|
|
efi_virtmap_unload(); \
|
|
kernel_neon_end(); \
|
|
__s; \
|
|
})
|
|
|
|
#define __efi_call_virt(f, ...) \
|
|
({ \
|
|
efi_##f##_t *__f; \
|
|
\
|
|
kernel_neon_begin(); \
|
|
efi_virtmap_load(); \
|
|
__f = efi.systab->runtime->f; \
|
|
__f(__VA_ARGS__); \
|
|
efi_virtmap_unload(); \
|
|
kernel_neon_end(); \
|
|
})
|
|
|
|
/* arch specific definitions used by the stub code */
|
|
|
|
/*
|
|
* AArch64 requires the DTB to be 8-byte aligned in the first 512MiB from
|
|
* start of kernel and may not cross a 2MiB boundary. We set alignment to
|
|
* 2MiB so we know it won't cross a 2MiB boundary.
|
|
*/
|
|
#define EFI_FDT_ALIGN SZ_2M /* used by allocate_new_fdt_and_exit_boot() */
|
|
#define MAX_FDT_OFFSET SZ_512M
|
|
|
|
#define efi_call_early(f, ...) sys_table_arg->boottime->f(__VA_ARGS__)
|
|
|
|
#define EFI_ALLOC_ALIGN SZ_64K
|
|
|
|
/*
|
|
* On ARM systems, virtually remapped UEFI runtime services are set up in two
|
|
* distinct stages:
|
|
* - The stub retrieves the final version of the memory map from UEFI, populates
|
|
* the virt_addr fields and calls the SetVirtualAddressMap() [SVAM] runtime
|
|
* service to communicate the new mapping to the firmware (Note that the new
|
|
* mapping is not live at this time)
|
|
* - During an early initcall(), the EFI system table is permanently remapped
|
|
* and the virtual remapping of the UEFI Runtime Services regions is loaded
|
|
* into a private set of page tables. If this all succeeds, the Runtime
|
|
* Services are enabled and the EFI_RUNTIME_SERVICES bit set.
|
|
*/
|
|
|
|
static inline void efi_set_pgd(struct mm_struct *mm)
|
|
{
|
|
__switch_mm(mm);
|
|
|
|
if (system_uses_ttbr0_pan()) {
|
|
if (mm != current->active_mm) {
|
|
/*
|
|
* Update the current thread's saved ttbr0 since it is
|
|
* restored as part of a return from exception. Set
|
|
* the hardware TTBR0_EL1 using cpu_switch_mm()
|
|
* directly to enable potential errata workarounds.
|
|
*/
|
|
update_saved_ttbr0(current, mm);
|
|
cpu_switch_mm(mm->pgd, mm);
|
|
} else {
|
|
/*
|
|
* Defer the switch to the current thread's TTBR0_EL1
|
|
* until uaccess_enable(). Restore the current
|
|
* thread's saved ttbr0 corresponding to its active_mm
|
|
* (if different from init_mm).
|
|
*/
|
|
cpu_set_reserved_ttbr0();
|
|
if (current->active_mm != &init_mm)
|
|
update_saved_ttbr0(current, current->active_mm);
|
|
}
|
|
}
|
|
}
|
|
|
|
void efi_virtmap_load(void);
|
|
void efi_virtmap_unload(void);
|
|
|
|
#endif /* _ASM_EFI_H */
|