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authorPaul Walmsley <paul.walmsley@sifive.com>2019-09-13 18:35:50 -0700
committerPaul Walmsley <paul.walmsley@sifive.com>2019-09-13 19:03:52 -0700
commit474efecb65dceb15f793b6e2f2b226e952f0f8e9 (patch)
tree823295a3eb9436fe5e9277c553666caf3aa04adf /arch
parentf74c2bb98776e2de508f4d607cd519873065118e (diff)
downloadlwn-474efecb65dceb15f793b6e2f2b226e952f0f8e9.tar.gz
lwn-474efecb65dceb15f793b6e2f2b226e952f0f8e9.zip
riscv: modify the Image header to improve compatibility with the ARM64 header
Part of the intention during the definition of the RISC-V kernel image header was to lay the groundwork for a future merge with the ARM64 image header. One error during my original review was not noticing that the RISC-V header's "magic" field was at a different size and position than the ARM64's "magic" field. If the existing ARM64 Image header parsing code were to attempt to parse an existing RISC-V kernel image header format, it would see a magic number 0. This is undesirable, since it's our intention to align as closely as possible with the ARM64 header format. Another problem was that the original "res3" field was not being initialized correctly to zero. Address these issues by creating a 32-bit "magic2" field in the RISC-V header which matches the ARM64 "magic" field. RISC-V binaries will store "RSC\x05" in this field. The intention is that the use of the existing 64-bit "magic" field in the RISC-V header will be deprecated over time. Increment the minor version number of the file format to indicate this change, and update the documentation accordingly. Fix the assembler directives in head.S to ensure that reserved fields are properly zero-initialized. Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com> Reported-by: Palmer Dabbelt <palmer@sifive.com> Reviewed-by: Palmer Dabbelt <palmer@sifive.com> Cc: Atish Patra <atish.patra@wdc.com> Cc: Karsten Merker <merker@debian.org> Link: https://lore.kernel.org/linux-riscv/194c2f10c9806720623430dbf0cc59a965e50448.camel@wdc.com/T/#u Link: https://lore.kernel.org/linux-riscv/mhng-755b14c4-8f35-4079-a7ff-e421fd1b02bc@palmer-si-x1e/T/#t
Diffstat (limited to 'arch')
-rw-r--r--arch/riscv/include/asm/image.h12
-rw-r--r--arch/riscv/kernel/head.S4
2 files changed, 8 insertions, 8 deletions
diff --git a/arch/riscv/include/asm/image.h b/arch/riscv/include/asm/image.h
index ef28e106f247..344db5244547 100644
--- a/arch/riscv/include/asm/image.h
+++ b/arch/riscv/include/asm/image.h
@@ -3,7 +3,8 @@
#ifndef __ASM_IMAGE_H
#define __ASM_IMAGE_H
-#define RISCV_IMAGE_MAGIC "RISCV"
+#define RISCV_IMAGE_MAGIC "RISCV\0\0\0"
+#define RISCV_IMAGE_MAGIC2 "RSC\x05"
#define RISCV_IMAGE_FLAG_BE_SHIFT 0
#define RISCV_IMAGE_FLAG_BE_MASK 0x1
@@ -23,7 +24,7 @@
#define __HEAD_FLAGS (__HEAD_FLAG(BE))
#define RISCV_HEADER_VERSION_MAJOR 0
-#define RISCV_HEADER_VERSION_MINOR 1
+#define RISCV_HEADER_VERSION_MINOR 2
#define RISCV_HEADER_VERSION (RISCV_HEADER_VERSION_MAJOR << 16 | \
RISCV_HEADER_VERSION_MINOR)
@@ -39,9 +40,8 @@
* @version: version
* @res1: reserved
* @res2: reserved
- * @magic: Magic number
- * @res3: reserved (will be used for additional RISC-V specific
- * header)
+ * @magic: Magic number (RISC-V specific; deprecated)
+ * @magic2: Magic number 2 (to match the ARM64 'magic' field pos)
* @res4: reserved (will be used for PE COFF offset)
*
* The intention is for this header format to be shared between multiple
@@ -58,7 +58,7 @@ struct riscv_image_header {
u32 res1;
u64 res2;
u64 magic;
- u32 res3;
+ u32 magic2;
u32 res4;
};
#endif /* __ASSEMBLY__ */
diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
index 0f1ba17e476f..52eec0c1bf30 100644
--- a/arch/riscv/kernel/head.S
+++ b/arch/riscv/kernel/head.S
@@ -39,9 +39,9 @@ ENTRY(_start)
.word RISCV_HEADER_VERSION
.word 0
.dword 0
- .asciz RISCV_IMAGE_MAGIC
- .word 0
+ .ascii RISCV_IMAGE_MAGIC
.balign 4
+ .ascii RISCV_IMAGE_MAGIC2
.word 0
.global _start_kernel