[PATCH 13/14] ARM: module: correctly relocate instructions in BE8

Ben Dooks
2013-07-24T10:28:01Z

When in BE8 mode, our instructions are not in the same ordering as the
data, so use <asm/opcodes.h> to take this into account.

Note, also requires modules to be built --be8

Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
---
arch/arm/kernel/module.c | 57 +++++++++++++++++++++++++++-------------------
1 file changed, 34 insertions(+), 23 deletions(-)

diff --git a/arch/arm/kernel/module.c b/arch/arm/kernel/module.c
index 1e9be5d..7e13787 100644
--- a/arch/arm/kernel/module.c
+++ b/arch/arm/kernel/module.c
@@ -24,6 +24,7 @@
#include <asm/sections.h>
#include <asm/smp_plat.h>
#include <asm/unwind.h>
+#include <asm/opcodes.h>

#ifdef CONFIG_XIP_KERNEL
/*
@@ -60,6 +61,7 @@ apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex,
Elf32_Sym *sym;
const char *symname;
s32 offset;
+ u32 tmp;
#ifdef CONFIG_THUMB2_KERNEL
u32 upper, lower, sign, j1, j2;
#endif
@@ -95,7 +97,8 @@ 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 = __mem_to_opcode_arm(*(u32 *)loc);
+ offset = (offset & 0x00ffffff) << 2;
if (offset & 0x02000000)
offset -= 0x04000000;

@@ -111,9 +114,10 @@ apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex,
}

offset >>= 2;
+ offset &= 0x00ffffff;

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

case R_ARM_V4BX:
@@ -121,8 +125,8 @@ 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;
+ *(u32 *)loc &= __opcode_to_mem_arm(0xf000000f);
+ *(u32 *)loc |= __opcode_to_mem_arm(0x01a0f000);
break;

case R_ARM_PREL31:
@@ -132,7 +136,7 @@ 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 = tmp = __mem_to_opcode_arm(*(u32 *)loc);
offset = ((offset & 0xf0000) >> 4) | (offset & 0xfff);
offset = (offset ^ 0x8000) - 0x8000;

@@ -140,16 +144,18 @@ 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);
+ tmp &= 0xfff0f000;
+ tmp |= ((offset & 0xf000) << 4) |
+ (offset & 0x0fff);
+
+ *(u32 *)loc = __opcode_to_mem_arm(tmp);
break;

#ifdef CONFIG_THUMB2_KERNEL
case R_ARM_THM_CALL:
case R_ARM_THM_JUMP24:
- upper = *(u16 *)loc;
- lower = *(u16 *)(loc + 2);
+ upper = __mem_to_opcode_thumb16(*(u16 *)loc);
+ lower = __mem_to_opcode_thumb16(*(u16 *)(loc + 2));

/*
* 25 bit signed address range (Thumb-2 BL and B.W
@@ -198,17 +204,20 @@ 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) |
+ upper = (u16)((upper & 0xf800) | (sign << 10) |
((offset >> 12) & 0x03ff));
- *(u16 *)(loc + 2) = (u16)((lower & 0xd000) |
- (j1 << 13) | (j2 << 11) |
- ((offset >> 1) & 0x07ff));
+ lower = (u16)((lower & 0xd000) |
+ (j1 << 13) | (j2 << 11) |
+ ((offset >> 1) & 0x07ff));
+
+ *(u16 *)loc = __opcode_to_mem_thumb16(upper);
+ *(u16 *)(loc + 2) = __opcode_to_mem_thumb16(lower);
break;

case R_ARM_THM_MOVW_ABS_NC:
case R_ARM_THM_MOVT_ABS:
- upper = *(u16 *)loc;
- lower = *(u16 *)(loc + 2);
+ upper = __mem_to_opcode_thumb16(*(u16 *)loc);
+ lower = __mem_to_opcode_thumb16(*(u16 *)(loc + 2));

/*
* MOVT/MOVW instructions encoding in Thumb-2:
@@ -229,12 +238,14 @@ 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) |
- ((offset & 0xf000) >> 12) |
- ((offset & 0x0800) >> 1));
- *(u16 *)(loc + 2) = (u16)((lower & 0x8f00) |
- ((offset & 0x0700) << 4) |
- (offset & 0x00ff));
+ upper = (u16)((upper & 0xfbf0) |
+ ((offset & 0xf000) >> 12) |
+ ((offset & 0x0800) >> 1));
+ lower = (u16)((lower & 0x8f00) |
+ ((offset & 0x0700) << 4) |
+ (offset & 0x00ff));
+ *(u16 *)loc = __opcode_to_mem_thumb16(upper);
+ *(u16 *)(loc + 2) = __opcode_to_mem_thumb16(lower);
break;
#endif

--
1.7.10.4