UEFI: combine GetMemoryMap and ExitBootServices and retry on error

The EFI memory map may change before or during the first
ExitBootServices call. In that case ExitBootServices returns an error,
and GetMemoryMap and ExitBootServices must be retried.

Glue together calls to GetMemoryMap(), ExitBootServices() and storage of
(now up-to-date) MODINFOMD_EFI_MAP metadata within a single function.

That new function - bi_add_efi_data_and_exit() - uses space previously
allocated in bi_load_efi_data() to store the memory map (it will fail if
that space is too short). It handles re-calling GetMemoryMap() once to
update the map key if necessary. Finally, if ExitBootServices() is
successful, it stores the memory map and its header as MODINFOMD_EFI_MAP
metadata.

ExitBootServices() calls are now done earlier, from within arch-
independent bi_load() code.

PR:		202455
Submitted by:	Ganael LAPLANCHE
Reviewed by:	kib
MFC after:	2 weeks
Relnotes:	Yes
Differential Revision:	https://reviews.freebsd.org/D4296

sys/boot/efi/loader/arch/amd64/elf64_freebsd.c

@@ -174,13 +174,6 @@ elf64_exec(struct preloaded_file *fp)
 	if (err != 0)
 		return(err);
 
-	status = BS->ExitBootServices(IH, efi_mapkey);
-	if (EFI_ERROR(status)) {
-		printf("%s: ExitBootServices() returned 0x%lx\n", __func__,
-		    (long)status);
-		return (EINVAL);
-	}
-
 	dev_cleanup();
 
 	trampoline(trampstack, efi_copy_finish, kernend, modulep, PT4,

sys/boot/efi/loader/arch/arm/exec.c

@@ -82,13 +82,6 @@ __elfN(arm_exec)(struct preloaded_file *fp)
 	printf("modulep: %#x\n", modulep);
 	printf("relocation_offset %llx\n", __elfN(relocation_offset));
 
-	status = BS->ExitBootServices(IH, efi_mapkey);
-	if (EFI_ERROR(status)) {
-		printf("%s: ExitBootServices() returned 0x%lx\n", __func__,
-		    (long)status);
-		return (EINVAL);
-	}
-
 	dev_cleanup();
 
 	(*entry)((void *)modulep);

sys/boot/efi/loader/arch/arm64/exec.c

@@ -118,13 +118,6 @@ elf64_exec(struct preloaded_file *fp)
 	if (err != 0)
 		return (err);
 
-	status = BS->ExitBootServices(IH, efi_mapkey);
-        if (EFI_ERROR(status)) {
-		printf("%s: ExitBootServices() returned 0x%lx\n", __func__,
-		    (long)status);
-		return (EINVAL);
-	}
-
 	/* Clean D-cache under kernel area and invalidate whole I-cache */
 	clean_addr = efi_translate(fp->f_addr);
 	clean_size = efi_translate(kernendp) - clean_addr;

sys/boot/efi/loader/bootinfo.c

@@ -55,8 +55,6 @@ __FBSDID("$FreeBSD$");
 #include <fdt_platform.h>
 #endif
 
-UINTN efi_mapkey;
-
 static const char howto_switches[] = "aCdrgDmphsv";
 static int howto_masks[] = {
 	RB_ASKNAME, RB_CDROM, RB_KDB, RB_DFLTROOT, RB_GDB, RB_MULTIPLE,
@@ -233,6 +231,43 @@ bi_copymodules(vm_offset_t addr)
 	return(addr);
 }
 
+static int
+bi_add_efi_data_and_exit(struct preloaded_file *kfp,
+    struct efi_map_header *efihdr, size_t efisz, EFI_MEMORY_DESCRIPTOR *mm,
+    UINTN sz)
+{
+	UINTN efi_mapkey;
+	UINTN mmsz;
+	UINT32 mmver;
+	EFI_STATUS status;
+	UINTN retry;
+
+	/*
+	 * It is possible that the first call to ExitBootServices may change
+	 * the map key. Fetch a new map key and retry ExitBootServices in that
+	 * case.
+	 */
+	for (retry = 2; retry > 0; retry--) {
+		status = BS->GetMemoryMap(&sz, mm, &efi_mapkey, &mmsz, &mmver);
+		if (EFI_ERROR(status)) {
+			printf("%s: GetMemoryMap() returned 0x%lx\n", __func__,
+			    (long)status);
+			return (EINVAL);
+		}
+		status = BS->ExitBootServices(IH, efi_mapkey);
+		if (EFI_ERROR(status) == 0) {
+			efihdr->memory_size = sz;
+			efihdr->descriptor_size = mmsz;
+			efihdr->descriptor_version = mmver;
+			file_addmetadata(kfp, MODINFOMD_EFI_MAP, efisz + sz,
+			    efihdr);
+			return (0);
+		}
+	}
+	printf("ExitBootServices() returned 0x%lx\n", (long)status);
+	return (EINVAL);
+}
+
 static int
 bi_load_efi_data(struct preloaded_file *kfp)
 {
@@ -240,6 +275,7 @@ bi_load_efi_data(struct preloaded_file *kfp)
 	EFI_PHYSICAL_ADDRESS addr;
 	EFI_STATUS status;
 	size_t efisz;
+	UINTN efi_mapkey;
 	UINTN mmsz, pages, sz;
 	UINT32 mmver;
 	struct efi_map_header *efihdr;
@@ -294,20 +330,8 @@ bi_load_efi_data(struct preloaded_file *kfp)
 	efihdr = (struct efi_map_header *)addr;
 	mm = (void *)((uint8_t *)efihdr + efisz);
 	sz = (EFI_PAGE_SIZE * pages) - efisz;
-	status = BS->GetMemoryMap(&sz, mm, &efi_mapkey, &mmsz, &mmver);
-	if (EFI_ERROR(status)) {
-		printf("%s: GetMemoryMap() returned 0x%lx\n", __func__,
-		    (long)status);
-		return (EINVAL);
-	}
 
-	efihdr->memory_size = sz;
-	efihdr->descriptor_size = mmsz;
-	efihdr->descriptor_version = mmver;
-
-	file_addmetadata(kfp, MODINFOMD_EFI_MAP, efisz + sz, efihdr);
-
-	return (0);
+	return (bi_add_efi_data_and_exit(kfp, efihdr, efisz, mm, sz));
 }
 
 /*

sys/boot/efi/loader/loader_efi.h

@@ -44,8 +44,6 @@ ssize_t	efi_copyout(const vm_offset_t src, void *dest, const size_t len);
 ssize_t	efi_readin(const int fd, vm_offset_t dest, const size_t len);
 void * efi_translate(vm_offset_t ptr);
 
-extern UINTN efi_mapkey;
-
 void	efi_copy_finish(void);
 
 #endif	/* _LOADER_EFI_COPY_H_ */