efi: Let architectures decide the flags that should be saved/restored

hulk inclusion
category: feature
bugzilla: 9291
CVE: NA

ported from https://lore.kernel.org/patchwork/patch/1037486/

--------------------------------

Currently, irqflags are saved before calling runtime services and
checked for mismatch on return.

Provide a pair of overridable macros to save and restore (if needed) the
state that need to be preserved on return from a runtime service.
This allows to check for flags that are not necesarly related to
irqflags.
Signed-off-by: NJulien Thierry <julien.thierry@arm.com>
Acked-by: NCatalin Marinas <catalin.marinas@arm.com>
Acked-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: NMarc Zyngier <marc.zyngier@arm.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: linux-efi@vger.kernel.org
Signed-off-by: NWei Li <liwei391@huawei.com>
Reviewed-by: NHanjun Guo <guohanjun@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

drivers/firmware/efi/runtime-wrappers.c

@@ -115,11 +115,24 @@ struct efi_runtime_work {
 	efi_rts_work.status;						\
 })
 
+#ifndef arch_efi_save_flags
+#define arch_efi_save_flags(state_flags)	local_save_flags(state_flags)
+#define arch_efi_restore_flags(state_flags)	local_irq_restore(state_flags)
+#endif
+
+unsigned long efi_call_virt_save_flags(void)
+{
+	unsigned long flags;
+
+	arch_efi_save_flags(flags);
+	return flags;
+}
+
 void efi_call_virt_check_flags(unsigned long flags, const char *call)
 {
 	unsigned long cur_flags, mismatch;
 
-	local_save_flags(cur_flags);
+	cur_flags = efi_call_virt_save_flags();
 
 	mismatch = flags ^ cur_flags;
 	if (!WARN_ON_ONCE(mismatch & ARCH_EFI_IRQ_FLAGS_MASK))
@@ -128,7 +141,7 @@ void efi_call_virt_check_flags(unsigned long flags, const char *call)
 	add_taint(TAINT_FIRMWARE_WORKAROUND, LOCKDEP_NOW_UNRELIABLE);
 	pr_err_ratelimited(FW_BUG "IRQ flags corrupted (0x%08lx=>0x%08lx) by EFI %s\n",
 			   flags, cur_flags, call);
-	local_irq_restore(flags);
+	arch_efi_restore_flags(flags);
 }
 
 /*

include/linux/efi.h

@@ -1576,6 +1576,7 @@ efi_status_t efi_setup_gop(efi_system_table_t *sys_table_arg,
 
 bool efi_runtime_disabled(void);
 extern void efi_call_virt_check_flags(unsigned long flags, const char *call);
+extern unsigned long efi_call_virt_save_flags(void);
 
 enum efi_secureboot_mode {
 	efi_secureboot_mode_unset,
@@ -1621,7 +1622,7 @@ void efi_retrieve_tpm2_eventlog(efi_system_table_t *sys_table);
 									\
 	arch_efi_call_virt_setup();					\
 									\
-	local_save_flags(__flags);					\
+	__flags = efi_call_virt_save_flags();				\
 	__s = arch_efi_call_virt(p, f, args);				\
 	efi_call_virt_check_flags(__flags, __stringify(f));		\
 									\
@@ -1636,7 +1637,7 @@ void efi_retrieve_tpm2_eventlog(efi_system_table_t *sys_table);
 									\
 	arch_efi_call_virt_setup();					\
 									\
-	local_save_flags(__flags);					\
+	__flags = efi_call_virt_save_flags();				\
 	arch_efi_call_virt(p, f, args);					\
 	efi_call_virt_check_flags(__flags, __stringify(f));		\
 									\