x86, efi stub: Add .reloc section back into image

Some UEFI firmware will not load a .efi with a .reloc section
with a size of 0.

Therefore, we create a .efi image with 4 main areas and 3 sections.
1. PE/COFF file header
2. .setup section (covers all setup code following the first sector)
3. .reloc section (contains 1 dummy reloc entry, created in build.c)
4. .text section (covers the remaining kernel image)

To make room for the new .setup section data, the header
bugger_off_msg had to be shortened.

Reported-by: Henrik Rydberg <rydberg@euromail.se>
Signed-off-by: Jordan Justen <jordan.l.justen@intel.com>
Link: http://lkml.kernel.org/r/1339085121-12760-1-git-send-email-jordan.l.justen@intel.com
Tested-by: Lee G Rosenbaum <lee.g.rosenbaum@intel.com>
Tested-by: Henrik Rydberg <rydberg@euromail.se>
Cc: Matt Fleming <matt.fleming@intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

2 files changed, 140 insertions, 74 deletions

diff --git a/arch/x86/boot/header.S b/arch/x86/boot/header.S
index 8bbea6aa40d9..efe5acfc79c3 100644
--- a/arch/x86/boot/header.S
+++ b/arch/x86/boot/header.S
@@ -94,10 +94,10 @@ bs_die:
 
         .section ".bsdata", "a"
 bugger_off_msg:
-        .ascii  "Direct booting from floppy is no longer supported.\r\n"
-        .ascii  "Please use a boot loader program instead.\r\n"
+        .ascii  "Direct floppy boot is not supported. "
+        .ascii  "Use a boot loader program instead.\r\n"
         .ascii  "\n"
-        .ascii  "Remove disk and press any key to reboot . . .\r\n"
+        .ascii  "Remove disk and press any key to reboot ...\r\n"
         .byte   0
 
 #ifdef CONFIG_EFI_STUB
@@ -111,7 +111,7 @@ coff_header:
 #else
         .word   0x8664                          # x86-64
 #endif
-        .word   2                               # nr_sections
+        .word   3                               # nr_sections
         .long   0                               # TimeDateStamp
         .long   0                               # PointerToSymbolTable
         .long   1                               # NumberOfSymbols
@@ -158,8 +158,8 @@ extra_header_fields:
 #else
         .quad   0                               # ImageBase
 #endif
-        .long   0x1000                          # SectionAlignment
-        .long   0x200                           # FileAlignment
+        .long   0x20                            # SectionAlignment
+        .long   0x20                            # FileAlignment
         .word   0                               # MajorOperatingSystemVersion
         .word   0                               # MinorOperatingSystemVersion
         .word   0                               # MajorImageVersion
@@ -200,8 +200,10 @@ extra_header_fields:
 
         # Section table
 section_table:
-        .ascii  ".text"
-        .byte   0
+        #
+        # The offset & size fields are filled in by build.c.
+        #
+        .ascii  ".setup"
         .byte   0
         .byte   0
         .long   0
@@ -217,9 +219,8 @@ section_table:
 
         #
         # The EFI application loader requires a relocation section
-        # because EFI applications must be relocatable. But since
-        # we don't need the loader to fixup any relocs for us, we
-        # just create an empty (zero-length) .reloc section header.
+        # because EFI applications must be relocatable. The .reloc
+        # offset & size fields are filled in by build.c.
         #
         .ascii  ".reloc"
         .byte   0
@@ -233,6 +234,25 @@ section_table:
         .word   0                               # NumberOfRelocations
         .word   0                               # NumberOfLineNumbers
         .long   0x42100040                      # Characteristics (section flags)
+
+        #
+        # The offset & size fields are filled in by build.c.
+        #
+        .ascii  ".text"
+        .byte   0
+        .byte   0
+        .byte   0
+        .long   0
+        .long   0x0                             # startup_{32,64}
+        .long   0                               # Size of initialized data
+                                                # on disk
+        .long   0x0                             # startup_{32,64}
+        .long   0                               # PointerToRelocations
+        .long   0                               # PointerToLineNumbers
+        .word   0                               # NumberOfRelocations
+        .word   0                               # NumberOfLineNumbers
+        .long   0x60500020                      # Characteristics (section flags)
+
 #endif /* CONFIG_EFI_STUB */
 
         # Kernel attributes; used by setup.  This is part 1 of the
diff --git a/arch/x86/boot/tools/build.c b/arch/x86/boot/tools/build.c
index 3f61f6e2b46f..4b8e165ee572 100644
--- a/arch/x86/boot/tools/build.c
+++ b/arch/x86/boot/tools/build.c
@@ -50,6 +50,8 @@ typedef unsigned int   u32;
 u8 buf[SETUP_SECT_MAX*512];
 int is_big_kernel;
 
+#define PECOFF_RELOC_RESERVE 0x20
+
 /*----------------------------------------------------------------------*/
 
 static const u32 crctab32[] = {
@@ -133,11 +135,103 @@ static void usage(void)
         die("Usage: build setup system [> image]");
 }
 
-int main(int argc, char ** argv)
-{
 #ifdef CONFIG_EFI_STUB
-        unsigned int file_sz, pe_header;
+
+static void update_pecoff_section_header(char *section_name, u32 offset, u32 size)
+{
+        unsigned int pe_header;
+        unsigned short num_sections;
+        u8 *section;
+
+        pe_header = get_unaligned_le32(&buf[0x3c]);
+        num_sections = get_unaligned_le16(&buf[pe_header + 6]);
+
+#ifdef CONFIG_X86_32
+        section = &buf[pe_header + 0xa8];
+#else
+        section = &buf[pe_header + 0xb8];
 #endif
+
+        while (num_sections > 0) {
+                if (strncmp((char*)section, section_name, 8) == 0) {
+                        /* section header size field */
+                        put_unaligned_le32(size, section + 0x8);
+
+                        /* section header vma field */
+                        put_unaligned_le32(offset, section + 0xc);
+
+                        /* section header 'size of initialised data' field */
+                        put_unaligned_le32(size, section + 0x10);
+
+                        /* section header 'file offset' field */
+                        put_unaligned_le32(offset, section + 0x14);
+
+                        break;
+                }
+                section += 0x28;
+                num_sections--;
+        }
+}
+
+static void update_pecoff_setup_and_reloc(unsigned int size)
+{
+        u32 setup_offset = 0x200;
+        u32 reloc_offset = size - PECOFF_RELOC_RESERVE;
+        u32 setup_size = reloc_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]);
+}
+
+static void update_pecoff_text(unsigned int text_start, unsigned int file_sz)
+{
+        unsigned int pe_header;
+        unsigned int text_sz = file_sz - text_start;
+
+        pe_header = get_unaligned_le32(&buf[0x3c]);
+
+        /* Size of image */
+        put_unaligned_le32(file_sz, &buf[pe_header + 0x50]);
+
+        /*
+         * Size of code: Subtract the size of the first sector (512 bytes)
+         * which includes the header.
+         */
+        put_unaligned_le32(file_sz - 512, &buf[pe_header + 0x1c]);
+
+#ifdef CONFIG_X86_32
+        /*
+         * Address of entry point.
+         *
+         * The EFI stub entry point is +16 bytes from the start of
+         * the .text section.
+         */
+        put_unaligned_le32(text_start + 16, &buf[pe_header + 0x28]);
+#else
+        /*
+         * Address of entry point. startup_32 is at the beginning and
+         * the 64-bit entry point (startup_64) is always 512 bytes
+         * after. The EFI stub entry point is 16 bytes after that, as
+         * the first instruction allows legacy loaders to jump over
+         * the EFI stub initialisation
+         */
+        put_unaligned_le32(text_start + 528, &buf[pe_header + 0x28]);
+#endif /* CONFIG_X86_32 */
+
+        update_pecoff_section_header(".text", text_start, text_sz);
+}
+
+#endif /* CONFIG_EFI_STUB */
+
+int main(int argc, char ** argv)
+{
         unsigned int i, sz, setup_sectors;
         int c;
         u32 sys_size;
@@ -163,6 +257,12 @@ int main(int argc, char ** argv)
                 die("Boot block hasn't got boot flag (0xAA55)");
         fclose(file);
 
+#ifdef CONFIG_EFI_STUB
+        /* Reserve 0x20 bytes for .reloc section */
+        memset(buf+c, 0, PECOFF_RELOC_RESERVE);
+        c += PECOFF_RELOC_RESERVE;
+#endif
+
         /* Pad unused space with zeros */
         setup_sectors = (c + 511) / 512;
         if (setup_sectors < SETUP_SECT_MIN)
@@ -170,6 +270,10 @@ int main(int argc, char ** argv)
         i = setup_sectors*512;
         memset(buf+c, 0, i-c);
 
+#ifdef CONFIG_EFI_STUB
+        update_pecoff_setup_and_reloc(i);
+#endif
+
         /* Set the default root device */
         put_unaligned_le16(DEFAULT_ROOT_DEV, &buf[508]);
 
@@ -194,66 +298,8 @@ int main(int argc, char ** argv)
         put_unaligned_le32(sys_size, &buf[0x1f4]);
 
 #ifdef CONFIG_EFI_STUB
-        file_sz = sz + i + ((sys_size * 16) - sz);
-
-        pe_header = get_unaligned_le32(&buf[0x3c]);
-
-        /* Size of image */
-        put_unaligned_le32(file_sz, &buf[pe_header + 0x50]);
-
-        /*
-         * Subtract the size of the first section (512 bytes) which
-         * includes the header and .reloc section. The remaining size
-         * is that of the .text section.
-         */
-        file_sz -= 512;
-
-        /* Size of code */
-        put_unaligned_le32(file_sz, &buf[pe_header + 0x1c]);
-
-#ifdef CONFIG_X86_32
-        /*
-         * Address of entry point.
-         *
-         * The EFI stub entry point is +16 bytes from the start of
-         * the .text section.
-         */
-        put_unaligned_le32(i + 16, &buf[pe_header + 0x28]);
-
-        /* .text size */
-        put_unaligned_le32(file_sz, &buf[pe_header + 0xb0]);
-
-        /* .text vma */
-        put_unaligned_le32(0x200, &buf[pe_header + 0xb4]);
-
-        /* .text size of initialised data */
-        put_unaligned_le32(file_sz, &buf[pe_header + 0xb8]);
-
-        /* .text file offset */
-        put_unaligned_le32(0x200, &buf[pe_header + 0xbc]);
-#else
-        /*
-         * Address of entry point. startup_32 is at the beginning and
-         * the 64-bit entry point (startup_64) is always 512 bytes
-         * after. The EFI stub entry point is 16 bytes after that, as
-         * the first instruction allows legacy loaders to jump over
-         * the EFI stub initialisation
-         */
-        put_unaligned_le32(i + 528, &buf[pe_header + 0x28]);
-
-        /* .text size */
-        put_unaligned_le32(file_sz, &buf[pe_header + 0xc0]);
-
-        /* .text vma */
-        put_unaligned_le32(0x200, &buf[pe_header + 0xc4]);
-
-        /* .text size of initialised data */
-        put_unaligned_le32(file_sz, &buf[pe_header + 0xc8]);
-
-        /* .text file offset */
-        put_unaligned_le32(0x200, &buf[pe_header + 0xcc]);
-#endif /* CONFIG_X86_32 */
-#endif /* CONFIG_EFI_STUB */
+        update_pecoff_text(setup_sectors * 512, sz + i + ((sys_size * 16) - sz));
+#endif
 
         crc = partial_crc32(buf, i, crc);
         if (fwrite(buf, 1, i, stdout) != i)