[PATCH v9 1/6] riscv: Prepare EFI header for relocatable kernels

Alexandre Ghiti
2023-03-29T04:54:45Z

ld does not handle relocations correctly as explained here [1],
a fix for that was proposed by Nelson there but we have to support older
toolchains and then provide this fix.

Note that llvm does not need this fix and is then excluded.

[1] https://sourceware.org/pipermail/binutils/2023-March/126690.html

Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
---
arch/riscv/include/asm/set_memory.h | 3 +++
arch/riscv/kernel/efi-header.S | 19 ++++++++++++++++---
arch/riscv/kernel/vmlinux.lds.S | 5 ++---
3 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/arch/riscv/include/asm/set_memory.h b/arch/riscv/include/asm/set_memory.h
index a2c14d4b3993..ec11001c3fe0 100644
--- a/arch/riscv/include/asm/set_memory.h
+++ b/arch/riscv/include/asm/set_memory.h
@@ -56,4 +56,7 @@ bool kernel_page_present(struct page *page);
#define SECTION_ALIGN L1_CACHE_BYTES
#endif /* CONFIG_STRICT_KERNEL_RWX */

+#define PECOFF_SECTION_ALIGNMENT 0x1000
+#define PECOFF_FILE_ALIGNMENT 0x200
+
#endif /* _ASM_RISCV_SET_MEMORY_H */
diff --git a/arch/riscv/kernel/efi-header.S b/arch/riscv/kernel/efi-header.S
index 8e733aa48ba6..515b2dfbca75 100644
--- a/arch/riscv/kernel/efi-header.S
+++ b/arch/riscv/kernel/efi-header.S
@@ -6,6 +6,7 @@

#include <linux/pe.h>
#include <linux/sizes.h>
+#include <asm/set_memory.h>

.macro __EFI_PE_HEADER
.long PE_MAGIC
@@ -33,7 +34,11 @@ optional_header:
.byte 0x02 // MajorLinkerVersion
.byte 0x14 // MinorLinkerVersion
.long __pecoff_text_end - efi_header_end // SizeOfCode
- .long __pecoff_data_virt_size // SizeOfInitializedData
+#ifdef __clang__
+ .long __pecoff_data_virt_size // SizeOfInitializedData
+#else
+ .long __pecoff_data_virt_end - __pecoff_text_end // SizeOfInitializedData
+#endif
.long 0 // SizeOfUninitializedData
.long __efistub_efi_pe_entry - _start // AddressOfEntryPoint
.long efi_header_end - _start // BaseOfCode
@@ -91,9 +96,17 @@ section_table:
IMAGE_SCN_MEM_EXECUTE // Characteristics

.ascii ".data\0\0\0"
- .long __pecoff_data_virt_size // VirtualSize
+#ifdef __clang__
+ .long __pecoff_data_virt_size // VirtualSize
+#else
+ .long __pecoff_data_virt_end - __pecoff_text_end // VirtualSize
+#endif
.long __pecoff_text_end - _start // VirtualAddress
- .long __pecoff_data_raw_size // SizeOfRawData
+#ifdef __clang__
+ .long __pecoff_data_raw_size // SizeOfRawData
+#else
+ .long __pecoff_data_raw_end - __pecoff_text_end // SizeOfRawData
+#endif
.long __pecoff_text_end - _start // PointerToRawData

.long 0 // PointerToRelocations
diff --git a/arch/riscv/kernel/vmlinux.lds.S b/arch/riscv/kernel/vmlinux.lds.S
index 53a8ad65b255..1c38294580c0 100644
--- a/arch/riscv/kernel/vmlinux.lds.S
+++ b/arch/riscv/kernel/vmlinux.lds.S
@@ -27,9 +27,6 @@ ENTRY(_start)

jiffies = jiffies_64;

-PECOFF_SECTION_ALIGNMENT = 0x1000;
-PECOFF_FILE_ALIGNMENT = 0x200;
-
SECTIONS
{
/* Beginning of code and text segment */
@@ -132,6 +129,7 @@ SECTIONS
#ifdef CONFIG_EFI
.pecoff_edata_padding : { BYTE(0); . = ALIGN(PECOFF_FILE_ALIGNMENT); }
__pecoff_data_raw_size = ABSOLUTE(. - __pecoff_text_end);
+ __pecoff_data_raw_end = ABSOLUTE(.);
#endif

/* End of data section */
@@ -142,6 +140,7 @@ SECTIONS
#ifdef CONFIG_EFI
. = ALIGN(PECOFF_SECTION_ALIGNMENT);
__pecoff_data_virt_size = ABSOLUTE(. - __pecoff_text_end);
+ __pecoff_data_virt_end = ABSOLUTE(.);
#endif
_end = .;