[PATCH 3/5] efi/zboot: Disentangle efi_remap_image() from efi_cache_sync_image()

[Ard Biesheuvel <ardb+git@google.com>]

From: Ard Biesheuvel <ardb@kernel.org>

Refactor efi_cache_sync_image() so that it is not in charge of calling
efi_remap_image(), which is really the wrong way around.

Instead, call efi_remap_image() from the primary zboot procedure, where
it is more straight-forward to obtain the code size from the loaded
image.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 arch/arm64/include/asm/efi.h           |  3 +++
 drivers/firmware/efi/libstub/arm64.c   |  2 --
 drivers/firmware/efi/libstub/efistub.h |  4 ++++
 drivers/firmware/efi/libstub/zboot.c   | 23 +++++++++++++++++++-
 4 files changed, 29 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/efi.h b/arch/arm64/include/asm/efi.h
index e8a9783235cb..da6afd4a7a27 100644
--- a/arch/arm64/include/asm/efi.h
+++ b/arch/arm64/include/asm/efi.h
@@ -151,4 +151,7 @@ efi_status_t efi_handle_corrupted_x18(efi_status_t s, const char *f);
 
 void efi_icache_sync(unsigned long start, unsigned long end);
 
+// temporary resolution for efistub_get_code_size()
+#define efistub_get_code_size(image_info) ({ extern u32 code_size; code_size; })
+
 #endif /* _ASM_EFI_H */
diff --git a/drivers/firmware/efi/libstub/arm64.c b/drivers/firmware/efi/libstub/arm64.c
index e57cd3de0a00..7ab634e37cf1 100644
--- a/drivers/firmware/efi/libstub/arm64.c
+++ b/drivers/firmware/efi/libstub/arm64.c
@@ -112,8 +112,6 @@ void efi_cache_sync_image(unsigned long image_base,
 	asm("ic ialluis");
 	dsb(ish);
 	isb();
-
-	efi_remap_image(image_base, alloc_size, code_size);
 }
 
 unsigned long __weak primary_entry_offset(void)
diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h
index 1955cdb5139a..89cd2ae57a3c 100644
--- a/drivers/firmware/efi/libstub/efistub.h
+++ b/drivers/firmware/efi/libstub/efistub.h
@@ -1270,4 +1270,8 @@ void arch_accept_memory(phys_addr_t start, phys_addr_t end);
 efi_status_t efi_zboot_decompress_init(unsigned long *alloc_size);
 efi_status_t efi_zboot_decompress(u8 *out, unsigned long outlen);
 
+#ifndef efistub_get_code_size
+#define efistub_get_code_size(image_info)	0
+#endif
+
 #endif
diff --git a/drivers/firmware/efi/libstub/zboot.c b/drivers/firmware/efi/libstub/zboot.c
index 97ae706c034a..27f6661253c0 100644
--- a/drivers/firmware/efi/libstub/zboot.c
+++ b/drivers/firmware/efi/libstub/zboot.c
@@ -36,6 +36,26 @@ const struct efi_image_info * __weak zboot_get_image_info(unsigned long image_ba
 	return NULL;
 }
 
+static efi_status_t efi_zboot_remap_image(const struct efi_image_info *image_info,
+					  unsigned long image_base,
+					  unsigned long image_size)
+{
+	unsigned long code_size = efistub_get_code_size(image_info);
+	efi_status_t status;
+
+	if (code_size) {
+		efi_cache_sync_image(image_base, code_size);
+
+		status = efi_remap_image(image_base, image_size, code_size);
+		if (status != EFI_SUCCESS)
+			return status;
+	} else {
+		efi_cache_sync_image(image_base, image_size);
+	}
+
+	return EFI_SUCCESS;
+}
+
 asmlinkage efi_status_t __efiapi
 efi_zboot_entry(efi_handle_t handle, efi_system_table_t *systab)
 {
@@ -103,7 +123,8 @@ efi_zboot_entry(efi_handle_t handle, efi_system_table_t *systab)
 		goto error;
 
 	auto image_info = zboot_get_image_info(image_base);
-	status = efi_stub_common(handle, image, image_base, cmdline_ptr,
+	status = efi_zboot_remap_image(image_info, image_base, alloc_size) ?:
+	         efi_stub_common(handle, image, image_base, cmdline_ptr,
 				 image_info);
 
 error:
-- 
2.56.0.455.g6c5a503b38-goog