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Subject[PATCH 1/3] Support BE8 mode kernel modules relocation
Date
The code section in BE8 kernel modules is in little-endian while data
section is in big-endian. When reading code from memory in the relocation
procedure, these instructions are read according to big-endian, so they
need to be inverted before writing to memory and after reading from memory.

Signed-off-by: Stanley.Miao <stanley.miao@windriver.com>
---
arch/arm/Makefile | 1 +
arch/arm/include/asm/io.h | 12 ++++++++++
arch/arm/kernel/module.c | 51 ++++++++++++++++++++++++--------------------
3 files changed, 41 insertions(+), 23 deletions(-)

diff --git a/arch/arm/Makefile b/arch/arm/Makefile
index 3eec793..03e7761 100644
--- a/arch/arm/Makefile
+++ b/arch/arm/Makefile
@@ -13,6 +13,7 @@
LDFLAGS_vmlinux :=-p --no-undefined -X
ifeq ($(CONFIG_CPU_ENDIAN_BE8),y)
LDFLAGS_vmlinux += --be8
+LDFLAGS_MODULE += --be8
endif

OBJCOPYFLAGS :=-O binary -R .note -R .note.gnu.build-id -R .comment -S
diff --git a/arch/arm/include/asm/io.h b/arch/arm/include/asm/io.h
index 815efa2..2f088c5 100644
--- a/arch/arm/include/asm/io.h
+++ b/arch/arm/include/asm/io.h
@@ -233,6 +233,18 @@ extern void _memset_io(volatile void __iomem *, int, size_t);

#endif /* __mem_pci */

+#ifdef CONFIG_CPU_ENDIAN_BE8
+#define read_instr32(c) __swab32(*(u32 *)c)
+#define read_instr16(c) __swab16(*(u16 *)c)
+#define write_instr32(v,a) (*(u32 *)(a) = __swab32((__force __u32)(v)))
+#define write_instr16(v,a) (*(u16 *)(a) = __swab16((__force __u16)(v)))
+#else
+#define read_instr32(c) (*(u32 *)c)
+#define read_instr16(c) (*(u16 *)c)
+#define write_instr32(v,a) (*(u32 *)(a) = (v))
+#define write_instr16(v,a) (*(u16 *)(a) = (v))
+#endif
+
/*
* ioremap and friends.
*
diff --git a/arch/arm/kernel/module.c b/arch/arm/kernel/module.c
index d9bd786..9c58a0d 100644
--- a/arch/arm/kernel/module.c
+++ b/arch/arm/kernel/module.c
@@ -14,6 +14,7 @@
#include <linux/moduleloader.h>
#include <linux/kernel.h>
#include <linux/mm.h>
+#include <linux/io.h>
#include <linux/elf.h>
#include <linux/vmalloc.h>
#include <linux/fs.h>
@@ -148,7 +149,7 @@ apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex,
case R_ARM_PC24:
case R_ARM_CALL:
case R_ARM_JUMP24:
- offset = (*(u32 *)loc & 0x00ffffff) << 2;
+ offset = (read_instr32(loc) & 0x00ffffff) << 2;
if (offset & 0x02000000)
offset -= 0x04000000;

@@ -165,8 +166,8 @@ apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex,

offset >>= 2;

- *(u32 *)loc &= 0xff000000;
- *(u32 *)loc |= offset & 0x00ffffff;
+ write_instr32((read_instr32(loc) & 0xff000000) |
+ (offset & 0x00ffffff), loc);
break;

case R_ARM_V4BX:
@@ -174,9 +175,9 @@ apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex,
* other bits to re-code instruction as
* MOV PC,Rm.
*/
- *(u32 *)loc &= 0xf000000f;
- *(u32 *)loc |= 0x01a0f000;
- break;
+ write_instr32((read_instr32(loc) & 0xf000000f) |
+ 0x01a0f000, loc);
+ break;

case R_ARM_PREL31:
offset = *(u32 *)loc + sym->st_value - loc;
@@ -185,7 +186,7 @@ apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex,

case R_ARM_MOVW_ABS_NC:
case R_ARM_MOVT_ABS:
- offset = *(u32 *)loc;
+ offset = read_instr32(loc);
offset = ((offset & 0xf0000) >> 4) | (offset & 0xfff);
offset = (offset ^ 0x8000) - 0x8000;

@@ -193,16 +194,16 @@ apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex,
if (ELF32_R_TYPE(rel->r_info) == R_ARM_MOVT_ABS)
offset >>= 16;

- *(u32 *)loc &= 0xfff0f000;
- *(u32 *)loc |= ((offset & 0xf000) << 4) |
- (offset & 0x0fff);
+ write_instr32((read_instr32(loc) & 0xfff0f000) |
+ ((offset & 0xf000) << 4) |
+ (offset & 0x0fff), loc);
break;

#ifdef CONFIG_THUMB2_KERNEL
case R_ARM_THM_CALL:
case R_ARM_THM_JUMP24:
- upper = *(u16 *)loc;
- lower = *(u16 *)(loc + 2);
+ upper = read_instr16(loc);
+ lower = read_instr16(loc + 2);

/*
* 25 bit signed address range (Thumb-2 BL and B.W
@@ -242,17 +243,19 @@ apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex,
sign = (offset >> 24) & 1;
j1 = sign ^ (~(offset >> 23) & 1);
j2 = sign ^ (~(offset >> 22) & 1);
- *(u16 *)loc = (u16)((upper & 0xf800) | (sign << 10) |
- ((offset >> 12) & 0x03ff));
- *(u16 *)(loc + 2) = (u16)((lower & 0xd000) |
- (j1 << 13) | (j2 << 11) |
- ((offset >> 1) & 0x07ff));
+ write_instr16((u16)((upper & 0xf800) | (sign << 10) |
+ ((offset >> 12) & 0x03ff)),
+ loc);
+ write_instr16((u16)((lower & 0xd000) |
+ (j1 << 13) | (j2 << 11) |
+ ((offset >> 1) & 0x07ff)),
+ loc + 2);
break;

case R_ARM_THM_MOVW_ABS_NC:
case R_ARM_THM_MOVT_ABS:
- upper = *(u16 *)loc;
- lower = *(u16 *)(loc + 2);
+ upper = read_instr16(loc);
+ lower = read_instr16(loc + 2);

/*
* MOVT/MOVW instructions encoding in Thumb-2:
@@ -273,12 +276,14 @@ apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex,
if (ELF32_R_TYPE(rel->r_info) == R_ARM_THM_MOVT_ABS)
offset >>= 16;

- *(u16 *)loc = (u16)((upper & 0xfbf0) |
+ write_instr16((u16)((upper & 0xfbf0) |
((offset & 0xf000) >> 12) |
- ((offset & 0x0800) >> 1));
- *(u16 *)(loc + 2) = (u16)((lower & 0x8f00) |
+ ((offset & 0x0800) >> 1)),
+ doc);
+ write_instr16((u16)((lower & 0x8f00) |
((offset & 0x0700) << 4) |
- (offset & 0x00ff));
+ (offset & 0x00ff)),
+ doc + 2);
break;
#endif

--
1.5.4.3


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