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From:   Ard Biesheuvel <ardb@kernel.org>
To:     linux-efi@vger.kernel.org
Cc:     linux-kernel@vger.kernel.org, Ard Biesheuvel <ardb@kernel.org>,
        Evgeniy Baskov <baskov@ispras.ru>,
        Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Ingo Molnar <mingo@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Peter Jones <pjones@redhat.com>,
        Matthew Garrett <mjg59@srcf.ucam.org>,
        Gerd Hoffmann <kraxel@redhat.com>,
        Kees Cook <keescook@chromium.org>,
        "H. Peter Anvin" <hpa@zytor.com>,
        =?UTF-8?q?Marvin=20H=C3=A4user?= <mhaeuser@posteo.de>
Subject: [PATCH 09/17] x86/boot: Set EFI handover offset directly in header asm
Date:   Fri, 18 Aug 2023 15:44:14 +0200
Message-Id: <20230818134422.380032-10-ardb@kernel.org>
In-Reply-To: <20230818134422.380032-1-ardb@kernel.org>
References: <20230818134422.380032-1-ardb@kernel.org>
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The offsets of the EFI handover entrypoints are available to the
assembler when constructing the header, so there is no need to set them
from the build tool afterwards.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 arch/x86/boot/header.S      | 18 ++++++++++++++-
 arch/x86/boot/tools/build.c | 24 --------------------
 2 files changed, 17 insertions(+), 25 deletions(-)

diff --git a/arch/x86/boot/header.S b/arch/x86/boot/header.S
index 5575d0f06bab1918..72744ba440f6ea09 100644
--- a/arch/x86/boot/header.S
+++ b/arch/x86/boot/header.S
@@ -524,8 +524,24 @@ pref_address:		.quad LOAD_PHYSICAL_ADDR	# preferred load addr
 # define INIT_SIZE VO_INIT_SIZE
 #endif
 
+	.macro		__handover_offset
+#ifndef CONFIG_EFI_HANDOVER_PROTOCOL
+	.long		0
+#elif !defined(CONFIG_X86_64)
+	.long		ZO_efi32_stub_entry
+#else
+	/* Yes, this is really how we defined it :( */
+	.long		ZO_efi64_stub_entry - 0x200
+#ifdef CONFIG_EFI_MIXED
+	.if		ZO_efi32_stub_entry != ZO_efi64_stub_entry - 0x200
+	.error		"32-bit and 64-bit EFI entry points do not match"
+	.endif
+#endif
+#endif
+	.endm
+
 init_size:		.long INIT_SIZE		# kernel initialization size
-handover_offset:	.long 0			# Filled in by build.c
+handover_offset:	__handover_offset
 kernel_info_offset:	.long ZO_kernel_info
 
 # End of setup header #####################################################
diff --git a/arch/x86/boot/tools/build.c b/arch/x86/boot/tools/build.c
index 14ef13fe7ab021e7..06949754316458ce 100644
--- a/arch/x86/boot/tools/build.c
+++ b/arch/x86/boot/tools/build.c
@@ -55,8 +55,6 @@ u8 buf[SETUP_SECT_MAX*512];
 #define PECOFF_COMPAT_RESERVE 0x0
 #endif
 
-static unsigned long efi32_stub_entry;
-static unsigned long efi64_stub_entry;
 static unsigned long efi_pe_entry;
 static unsigned long efi32_pe_entry;
 static unsigned long _end;
@@ -265,31 +263,12 @@ static void efi_stub_defaults(void)
 #endif
 }
 
-static void efi_stub_entry_update(void)
-{
-	unsigned long addr = efi32_stub_entry;
-
-#ifdef CONFIG_EFI_HANDOVER_PROTOCOL
-#ifdef CONFIG_X86_64
-	/* Yes, this is really how we defined it :( */
-	addr = efi64_stub_entry - 0x200;
-#endif
-
-#ifdef CONFIG_EFI_MIXED
-	if (efi32_stub_entry != addr)
-		die("32-bit and 64-bit EFI entry points do not match\n");
-#endif
-#endif
-	put_unaligned_le32(addr, &buf[0x264]);
-}
-
 #else
 
 static inline void update_pecoff_setup_and_reloc(unsigned int size) {}
 static inline void update_pecoff_text(unsigned int text_start,
 				      unsigned int file_sz) {}
 static inline void efi_stub_defaults(void) {}
-static inline void efi_stub_entry_update(void) {}
 
 static inline int reserve_pecoff_reloc_section(int c)
 {
@@ -332,8 +311,6 @@ static void parse_zoffset(char *fname)
 	p = (char *)buf;
 
 	while (p && *p) {
-		PARSE_ZOFS(p, efi32_stub_entry);
-		PARSE_ZOFS(p, efi64_stub_entry);
 		PARSE_ZOFS(p, efi_pe_entry);
 		PARSE_ZOFS(p, efi32_pe_entry);
 		PARSE_ZOFS(p, _end);
@@ -416,7 +393,6 @@ int main(int argc, char ** argv)
 
 	update_pecoff_text(setup_sectors * 512, i + (sys_size * 16));
 
-	efi_stub_entry_update();
 
 	crc = partial_crc32(buf, i, crc);
 	if (fwrite(buf, 1, i, dest) != i)
-- 
2.39.2