Merge tag 'efi-next-for-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull EFI updates from Ard Biesheuvel via Borislav Petkov:
 "A few cleanups left and right, some of which were part of a initrd
  measured boot series that needs some more work, and so only the
  cleanup patches have been included for this release"

* tag 'efi-next-for-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  efi/arm64: Update debug prints to reflect other entropy sources
  efi: x86: clean up previous struct mm switching
  efi: x86: move mixed mode stack PA variable out of 'efi_scratch'
  efi/libstub: move TPM related prototypes into efistub.h
  efi/libstub: fix prototype of efi_tcg2_protocol::get_event_log()
  efi/libstub: whitespace cleanup
  efi: ia64: move IA64-only declarations to new asm/efi.h header

3 files changed, 27 insertions, 28 deletions

diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
index c98f78330b09..1328b7959b72 100644
--- a/arch/x86/include/asm/efi.h
+++ b/arch/x86/include/asm/efi.h
@@ -12,6 +12,7 @@
 #include <linux/pgtable.h>
 
 extern unsigned long efi_fw_vendor, efi_config_table;
+extern unsigned long efi_mixed_mode_stack_pa;
 
 /*
  * We map the EFI regions needed for runtime services non-contiguously,
@@ -94,22 +95,12 @@ extern asmlinkage u64 __efi_call(void *fp, ...);
 	__efi_call(__VA_ARGS__);					\
 })
 
-/*
- * struct efi_scratch - Scratch space used while switching to/from efi_mm
- * @phys_stack: stack used during EFI Mixed Mode
- * @prev_mm:    store/restore stolen mm_struct while switching to/from efi_mm
- */
-struct efi_scratch {
-	u64			phys_stack;
-	struct mm_struct	*prev_mm;
-} __packed;
-
 #define arch_efi_call_virt_setup()					\
 ({									\
 	efi_sync_low_kernel_mappings();					\
 	kernel_fpu_begin();						\
 	firmware_restrict_branch_speculation_start();			\
-	efi_switch_mm(&efi_mm);						\
+	efi_enter_mm();							\
 })
 
 #define arch_efi_call_virt(p, f, args...)				\
@@ -117,7 +108,7 @@ struct efi_scratch {
 
 #define arch_efi_call_virt_teardown()					\
 ({									\
-	efi_switch_mm(efi_scratch.prev_mm);				\
+	efi_leave_mm();							\
 	firmware_restrict_branch_speculation_end();			\
 	kernel_fpu_end();						\
 })
@@ -136,7 +127,6 @@ struct efi_scratch {
 
 #endif /* CONFIG_X86_32 */
 
-extern struct efi_scratch efi_scratch;
 extern int __init efi_memblock_x86_reserve_range(void);
 extern void __init efi_print_memmap(void);
 extern void __init efi_map_region(efi_memory_desc_t *md);
@@ -149,10 +139,12 @@ extern void __init efi_dump_pagetable(void);
 extern void __init efi_apply_memmap_quirks(void);
 extern int __init efi_reuse_config(u64 tables, int nr_tables);
 extern void efi_delete_dummy_variable(void);
-extern void efi_switch_mm(struct mm_struct *mm);
 extern void efi_recover_from_page_fault(unsigned long phys_addr);
 extern void efi_free_boot_services(void);
 
+void efi_enter_mm(void);
+void efi_leave_mm(void);
+
 /* kexec external ABI */
 struct efi_setup_data {
 	u64 fw_vendor;
diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
index 8efd003540ca..bf85db683af4 100644
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -54,10 +54,7 @@
  * 0xffff_ffff_0000_0000 and limit EFI VA mapping space to 64G.
  */
 static u64 efi_va = EFI_VA_START;
-
-struct efi_scratch efi_scratch;
-
-EXPORT_SYMBOL_GPL(efi_mm);
+static struct mm_struct *efi_prev_mm;
 
 /*
  * We need our own copy of the higher levels of the page tables
@@ -237,7 +234,7 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages)
 		return 1;
 	}
 
-	efi_scratch.phys_stack = page_to_phys(page + 1); /* stack grows down */
+	efi_mixed_mode_stack_pa = page_to_phys(page + 1); /* stack grows down */
 
 	npages = (_etext - _text) >> PAGE_SHIFT;
 	text = __pa(_text);
@@ -462,11 +459,17 @@ void __init efi_dump_pagetable(void)
  * can not change under us.
  * It should be ensured that there are no concurent calls to this function.
  */
-void efi_switch_mm(struct mm_struct *mm)
+void efi_enter_mm(void)
+{
+	efi_prev_mm = current->active_mm;
+	current->active_mm = &efi_mm;
+	switch_mm(efi_prev_mm, &efi_mm, NULL);
+}
+
+void efi_leave_mm(void)
 {
-	efi_scratch.prev_mm = current->active_mm;
-	current->active_mm = mm;
-	switch_mm(efi_scratch.prev_mm, mm, NULL);
+	current->active_mm = efi_prev_mm;
+	switch_mm(&efi_mm, efi_prev_mm, NULL);
 }
 
 static DEFINE_SPINLOCK(efi_runtime_lock);
@@ -530,12 +533,12 @@ efi_thunk_set_virtual_address_map(unsigned long memory_map_size,
 	efi_sync_low_kernel_mappings();
 	local_irq_save(flags);
 
-	efi_switch_mm(&efi_mm);
+	efi_enter_mm();
 
 	status = __efi_thunk(set_virtual_address_map, memory_map_size,
 			     descriptor_size, descriptor_version, virtual_map);
 
-	efi_switch_mm(efi_scratch.prev_mm);
+	efi_leave_mm();
 	local_irq_restore(flags);
 
 	return status;
@@ -829,7 +832,7 @@ efi_set_virtual_address_map(unsigned long memory_map_size,
 							 descriptor_size,
 							 descriptor_version,
 							 virtual_map);
-	efi_switch_mm(&efi_mm);
+	efi_enter_mm();
 
 	kernel_fpu_begin();
 
@@ -845,7 +848,7 @@ efi_set_virtual_address_map(unsigned long memory_map_size,
 	/* grab the virtually remapped EFI runtime services table pointer */
 	efi.runtime = READ_ONCE(systab->runtime);
 
-	efi_switch_mm(efi_scratch.prev_mm);
+	efi_leave_mm();
 
 	return status;
 }
diff --git a/arch/x86/platform/efi/efi_thunk_64.S b/arch/x86/platform/efi/efi_thunk_64.S
index 26f0da238c1c..fd3dd1708eba 100644
--- a/arch/x86/platform/efi/efi_thunk_64.S
+++ b/arch/x86/platform/efi/efi_thunk_64.S
@@ -33,7 +33,7 @@ SYM_CODE_START(__efi64_thunk)
 	 * Switch to 1:1 mapped 32-bit stack pointer.
 	 */
 	movq	%rsp, %rax
-	movq	efi_scratch(%rip), %rsp
+	movq	efi_mixed_mode_stack_pa(%rip), %rsp
 	push	%rax
 
 	/*
@@ -70,3 +70,7 @@ SYM_CODE_START(__efi64_thunk)
 	pushl	%ebp
 	lret
 SYM_CODE_END(__efi64_thunk)
+
+	.bss
+	.balign 8
+SYM_DATA(efi_mixed_mode_stack_pa, .quad 0)