x86/boot: Drop PE/COFF .reloc section

Ancient buggy EFI loaders may have required a .reloc section to be
present at some point in time, but this has not been true for a long
time so the .reloc section can just be dropped.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230915171623.655440-16-ardb@google.com

diff --git a/arch/x86/boot/header.S b/arch/x86/boot/header.S
index 2b07bc596c398eae9f8a5b5c8c853ac7435e9d1c..9e9641e220a73a4a32c52e7fc265df83b9896ad4 100644 (file)
--- a/arch/x86/boot/header.S
+++ b/arch/x86/boot/header.S
@@ -155,26 +155,6 @@ section_table:
                IMAGE_SCN_MEM_READ              | \
                IMAGE_SCN_MEM_EXECUTE           # Characteristics
 
-       #
-       # The EFI application loader requires a relocation section
-       # because EFI applications must be relocatable. The .reloc
-       # offset & size fields are filled in by build.c.
-       #
-       .ascii  ".reloc"
-       .byte   0
-       .byte   0
-       .long   0
-       .long   0
-       .long   0                               # SizeOfRawData
-       .long   0                               # PointerToRawData
-       .long   0                               # PointerToRelocations
-       .long   0                               # PointerToLineNumbers
-       .word   0                               # NumberOfRelocations
-       .word   0                               # NumberOfLineNumbers
-       .long   IMAGE_SCN_CNT_INITIALIZED_DATA  | \
-               IMAGE_SCN_MEM_READ              | \
-               IMAGE_SCN_MEM_DISCARDABLE       # Characteristics
-
 #ifdef CONFIG_EFI_MIXED
        #
        # The offset & size fields are filled in by build.c.

diff --git a/arch/x86/boot/setup.ld b/arch/x86/boot/setup.ld
index 9bd5c1ada599d363c442853381bf043e354870bd..6d389499565c2d88081efba28f8e265d2d0fd1eb 100644 (file)
--- a/arch/x86/boot/setup.ld
+++ b/arch/x86/boot/setup.ld
@@ -40,8 +40,8 @@ SECTIONS
                setup_sig = .;
                LONG(0x5a5aaa55)
 
-               /* Reserve some extra space for the reloc and compat sections */
-               setup_size = ALIGN(ABSOLUTE(.) + 64, 512);
+               /* Reserve some extra space for the compat section */
+               setup_size = ALIGN(ABSOLUTE(.) + 32, 512);
                setup_sects = ABSOLUTE(setup_size / 512);
        }
 

diff --git a/arch/x86/boot/tools/build.c b/arch/x86/boot/tools/build.c
index 9712f27e32c10bb6a095fb46f588c2153e0c5b90..faccff9743a3af69c432948380d6ef2d9fc57b50 100644 (file)
--- a/arch/x86/boot/tools/build.c
+++ b/arch/x86/boot/tools/build.c
@@ -47,7 +47,6 @@ typedef unsigned int   u32;
 /* This must be large enough to hold the entire setup */
 u8 buf[SETUP_SECT_MAX*512];
 
-#define PECOFF_RELOC_RESERVE 0x20
 #define PECOFF_COMPAT_RESERVE 0x20
 
 static unsigned long efi32_pe_entry;
@@ -180,24 +179,13 @@ static void update_pecoff_section_header(char *section_name, u32 offset, u32 siz
        update_pecoff_section_header_fields(section_name, offset, size, size, offset);
 }
 
-static void update_pecoff_setup_and_reloc(unsigned int size)
+static void update_pecoff_setup(unsigned int size)
 {
        u32 setup_offset = 0x200;
-       u32 reloc_offset = size - PECOFF_RELOC_RESERVE - PECOFF_COMPAT_RESERVE;
-#ifdef CONFIG_EFI_MIXED
-       u32 compat_offset = reloc_offset + PECOFF_RELOC_RESERVE;
-#endif
-       u32 setup_size = reloc_offset - setup_offset;
+       u32 compat_offset = size - PECOFF_COMPAT_RESERVE;
+       u32 setup_size = compat_offset - setup_offset;
 
        update_pecoff_section_header(".setup", setup_offset, setup_size);
-       update_pecoff_section_header(".reloc", reloc_offset, PECOFF_RELOC_RESERVE);
-
-       /*
-        * Modify .reloc section contents with a single entry. The
-        * relocation is applied to offset 10 of the relocation section.
-        */
-       put_unaligned_le32(reloc_offset + 10, &buf[reloc_offset]);
-       put_unaligned_le32(10, &buf[reloc_offset + 4]);
 
 #ifdef CONFIG_EFI_MIXED
        update_pecoff_section_header(".compat", compat_offset, PECOFF_COMPAT_RESERVE);
@@ -214,21 +202,10 @@ static void update_pecoff_setup_and_reloc(unsigned int size)
 #endif
 }
 
-static int reserve_pecoff_reloc_section(int c)
-{
-       /* Reserve 0x20 bytes for .reloc section */
-       memset(buf+c, 0, PECOFF_RELOC_RESERVE);
-       return PECOFF_RELOC_RESERVE;
-}
-
 #else
 
-static inline void update_pecoff_setup_and_reloc(unsigned int size) {}
+static inline void update_pecoff_setup(unsigned int size) {}
 
-static inline int reserve_pecoff_reloc_section(int c)
-{
-       return 0;
-}
 #endif /* CONFIG_EFI_STUB */
 
 static int reserve_pecoff_compat_section(int c)
@@ -307,7 +284,6 @@ int main(int argc, char ** argv)
        fclose(file);
 
        c += reserve_pecoff_compat_section(c);
-       c += reserve_pecoff_reloc_section(c);
 
        /* Pad unused space with zeros */
        setup_sectors = (c + 511) / 512;
@@ -316,7 +292,7 @@ int main(int argc, char ** argv)
        i = setup_sectors*512;
        memset(buf+c, 0, i-c);
 
-       update_pecoff_setup_and_reloc(i);
+       update_pecoff_setup(i);
 
        /* Open and stat the kernel file */
        fd = open(argv[2], O_RDONLY);