[PATCH 1/3] Support BE8 mode kernel modules relocation

[Stanley.Miao]

Hi, Russell,

It looks no other comments. I uploaded these patches to you patches
tracking system.

Stanley.


2011/1/19, Stanley.Miao <stanley.miao at windriver.com>:
> 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 are
> needed to be inverted.
>
> Signed-off-by: Stanley.Miao <stanley.miao at windriver.com>
> ---
>  arch/arm/Makefile        |    1 +
>  arch/arm/kernel/module.c |   62
> +++++++++++++++++++++++++++++-----------------
>  2 files changed, 40 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/kernel/module.c b/arch/arm/kernel/module.c
> index d9bd786..c5e5bb1 100644
> --- a/arch/arm/kernel/module.c
> +++ b/arch/arm/kernel/module.c
> @@ -99,6 +99,18 @@ int module_frob_arch_sections(Elf_Ehdr *hdr,
>  	return 0;
>  }
>
> +#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
> +
>  int
>  apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int
> symindex,
>  	       unsigned int relindex, struct module *module)
> @@ -148,7 +160,7 @@ 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 +177,8 @@ 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 +186,9 @@ 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 +197,7 @@ 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 +205,16 @@ 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 +254,19 @@ 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 +287,14 @@ 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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