x86/efi: Implement support for embedding SBAT data for x86

Similar to zboot architectures, implement support for embedding SBAT data
for x86. Put '.sbat' section in between '.data' and '.text' as the former
also covers '.bss' and '.pgtable' and thus must be the last one in the
file.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/20250603091951.57775-1-vkuznets@redhat.com

6 files changed, 44 insertions, 11 deletions

diff --git a/arch/x86/boot/Makefile b/arch/x86/boot/Makefile
index 640fcac3af74..3f9fb3698d66 100644
--- a/arch/x86/boot/Makefile
+++ b/arch/x86/boot/Makefile
@@ -71,7 +71,7 @@ $(obj)/vmlinux.bin: $(obj)/compressed/vmlinux FORCE
 
 SETUP_OBJS = $(addprefix $(obj)/,$(setup-y))
 
-sed-zoffset := -e 's/^\([0-9a-fA-F]*\) [a-zA-Z] \(startup_32\|efi.._stub_entry\|efi\(32\)\?_pe_entry\|input_data\|kernel_info\|_end\|_ehead\|_text\|_e\?data\|z_.*\)$$/\#define ZO_\2 0x\1/p'
+sed-zoffset := -e 's/^\([0-9a-fA-F]*\) [a-zA-Z] \(startup_32\|efi.._stub_entry\|efi\(32\)\?_pe_entry\|input_data\|kernel_info\|_end\|_ehead\|_text\|_e\?data\|_e\?sbat\|z_.*\)$$/\#define ZO_\2 0x\1/p'
 
 quiet_cmd_zoffset = ZOFFSET $@
       cmd_zoffset = $(NM) $< | sed -n $(sed-zoffset) > $@
diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
index f4f7b22d8113..3a38fdcdb9bd 100644
--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
@@ -106,6 +106,11 @@ vmlinux-objs-$(CONFIG_UNACCEPTED_MEMORY) += $(obj)/mem.o
 vmlinux-objs-$(CONFIG_EFI) += $(obj)/efi.o
 vmlinux-libs-$(CONFIG_EFI_STUB) += $(objtree)/drivers/firmware/efi/libstub/lib.a
 vmlinux-libs-$(CONFIG_X86_64)	+= $(objtree)/arch/x86/boot/startup/lib.a
+vmlinux-objs-$(CONFIG_EFI_SBAT) += $(obj)/sbat.o
+
+ifdef CONFIG_EFI_SBAT
+$(obj)/sbat.o: $(CONFIG_EFI_SBAT_FILE)
+endif
 
 $(obj)/vmlinux: $(vmlinux-objs-y) $(vmlinux-libs-y) FORCE
 	$(call if_changed,ld)
diff --git a/arch/x86/boot/compressed/sbat.S b/arch/x86/boot/compressed/sbat.S
new file mode 100644
index 000000000000..838f70a997dd
--- /dev/null
+++ b/arch/x86/boot/compressed/sbat.S
@@ -0,0 +1,7 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Embed SBAT data in the kernel.
+ */
+	.pushsection ".sbat", "a", @progbits
+	.incbin CONFIG_EFI_SBAT_FILE
+	.popsection
diff --git a/arch/x86/boot/compressed/vmlinux.lds.S b/arch/x86/boot/compressed/vmlinux.lds.S
index 3b2bc61c9408..587ce3e7c504 100644
--- a/arch/x86/boot/compressed/vmlinux.lds.S
+++ b/arch/x86/boot/compressed/vmlinux.lds.S
@@ -43,6 +43,14 @@ SECTIONS
 		*(.rodata.*)
 		_erodata = . ;
 	}
+#ifdef CONFIG_EFI_SBAT
+	.sbat : ALIGN(0x1000) {
+		_sbat = . ;
+		*(.sbat)
+		_esbat = ALIGN(0x1000);
+		. = _esbat;
+	}
+#endif
 	.data :	ALIGN(0x1000) {
 		_data = . ;
 		*(.data)
diff --git a/arch/x86/boot/header.S b/arch/x86/boot/header.S
index e1f4fd5bc8ee..9bea5a1e2c52 100644
--- a/arch/x86/boot/header.S
+++ b/arch/x86/boot/header.S
@@ -179,15 +179,11 @@ pecompat_fstart:
 #else
 	.set	pecompat_fstart, setup_size
 #endif
-	.ascii	".text"
-	.byte	0
-	.byte	0
-	.byte	0
-	.long	ZO__data
-	.long	setup_size
-	.long	ZO__data			# Size of initialized data
-						# on disk
-	.long	setup_size
+	.ascii	".text\0\0\0"
+	.long	textsize            		# VirtualSize
+	.long	setup_size			# VirtualAddress
+	.long	textsize			# SizeOfRawData
+	.long	setup_size			# PointerToRawData
 	.long	0				# PointerToRelocations
 	.long	0				# PointerToLineNumbers
 	.word	0				# NumberOfRelocations
@@ -196,6 +192,23 @@ pecompat_fstart:
 		IMAGE_SCN_MEM_READ		| \
 		IMAGE_SCN_MEM_EXECUTE		# Characteristics
 
+#ifdef CONFIG_EFI_SBAT
+	.ascii	".sbat\0\0\0"
+	.long	ZO__esbat - ZO__sbat            # VirtualSize
+	.long	setup_size + ZO__sbat           # VirtualAddress
+	.long	ZO__esbat - ZO__sbat            # SizeOfRawData
+	.long	setup_size + ZO__sbat           # PointerToRawData
+
+	.long	0, 0, 0
+	.long	IMAGE_SCN_CNT_INITIALIZED_DATA	| \
+		IMAGE_SCN_MEM_READ		| \
+		IMAGE_SCN_MEM_DISCARDABLE	# Characteristics
+
+	.set	textsize, ZO__sbat
+#else
+	.set	textsize, ZO__data
+#endif
+
 	.ascii	".data\0\0\0"
 	.long	ZO__end - ZO__data		# VirtualSize
 	.long	setup_size + ZO__data		# VirtualAddress
diff --git a/drivers/firmware/efi/Kconfig b/drivers/firmware/efi/Kconfig
index db8c5c03d3a2..16baa038d412 100644
--- a/drivers/firmware/efi/Kconfig
+++ b/drivers/firmware/efi/Kconfig
@@ -286,7 +286,7 @@ config EFI_SBAT
 
 config EFI_SBAT_FILE
 	string "Embedded SBAT section file path"
-	depends on EFI_ZBOOT
+	depends on EFI_ZBOOT || (EFI_STUB && X86)
 	help
 	  SBAT section provides a way to improve SecureBoot revocations of UEFI
 	  binaries by introducing a generation-based mechanism. With SBAT, older