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x86: implement bss zero and data copy for application

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Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
This commit is contained in:
Andrew Boie 2017-06-19 11:17:23 -07:00 • committed by Anas Nashif
commit 3d8aaf7099
1 changed files with 77 additions and 54 deletions
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131
arch/x86/core/crt0.S
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@ -211,27 +211,15 @@ __csSet:
movl $__data_rom_start, %esi /* DATA in ROM (src) */
movl $__data_num_words, %ecx /* Size of DATA in quad bytes */
#ifdef CONFIG_SSE
/* copy 16 bytes at a time using XMM until < 16 bytes remain */
call _x86_data_copy
movl %ecx ,%edx /* save number of quad bytes */
shrl $2, %ecx /* How many 16 bytes? */
je dataWords
#ifdef CONFIG_APPLICATION_MEMORY
movl $__app_data_ram_start, %edi /* DATA in RAM (dest) */
movl $__app_data_rom_start, %esi /* DATA in ROM (src) */
movl $__app_data_num_words, %ecx /* Size of DATA in quad bytes */
dataDQ:
movdqu (%esi), %xmm0
movdqu %xmm0, (%edi)
addl $16, %esi
addl $16, %edi
loop dataDQ
dataWords:
movl %edx, %ecx /* restore # quad bytes */
andl $0x3, %ecx /* only need to copy at most 3 quad bytes */
#endif /* CONFIG_SSE */
rep
movsl /* copy data 4 bytes at a time */
call _x86_data_copy
#endif /* CONFIG_APPLICATION_MEMORY */
#endif /* CONFIG_XIP */
@ -241,44 +229,15 @@ dataWords:
* It's assumed that BSS size will be a multiple of a long (4 bytes),
* and aligned on a double word (32-bit) boundary
*/
#ifdef CONFIG_SSE
/* use XMM register to clear 16 bytes at a time */
pxor %xmm0, %xmm0 /* zero out xmm0 register */
movl $__bss_start, %edi /* load BSS start address */
movl $__bss_num_words, %ecx /* number of quad bytes in .bss */
movl %ecx, %edx /* make a copy of # quad bytes */
shrl $2, %ecx /* How many multiples of 16 byte ? */
je bssWords
bssDQ:
movdqu %xmm0, (%edi) /* zero 16 bytes... */
addl $16, %edi
loop bssDQ
call _x86_bss_zero
/* fall through to handle the remaining double words (32-bit chunks) */
bssWords:
xorl %eax, %eax /* fill memory with 0 */
movl %edx, %ecx /* move # quad bytes into ECX (for rep) */
andl $0x3, %ecx /* only need to zero at most 3 quad bytes */
cld
rep
stosl /* zero memory per 4 bytes */
#else /* !CONFIG_SSE */
/* clear out BSS double words (32-bits at a time) */
xorl %eax, %eax /* fill memory with 0 */
movl $__bss_start, %edi /* load BSS start address */
movl $__bss_num_words, %ecx /* number of quad bytes */
cld
rep
stosl /* zero memory per 4 bytes */
#endif /* CONFIG_SSE */
#ifdef CONFIG_APPLICATION_MEMORY
movl $__app_bss_start, %edi /* load app BSS start address */
movl $__app_bss_num_words, %ecx /* number of quad bytes */
call _x86_bss_zero
#endif
#ifdef CONFIG_GDT_DYNAMIC
/* activate RAM-based Global Descriptor Table (GDT) */
@ -308,6 +267,70 @@ bssWords:
jmp _Cstart
_x86_bss_zero:
/* ECX = size, EDI = starting address */
#ifdef CONFIG_SSE
/* use XMM register to clear 16 bytes at a time */
pxor %xmm0, %xmm0 /* zero out xmm0 register */
movl %ecx, %edx /* make a copy of # quad bytes */
shrl $2, %ecx /* How many multiples of 16 byte ? */
je bssWords
bssDQ:
movdqu %xmm0, (%edi) /* zero 16 bytes... */
addl $16, %edi
loop bssDQ
/* fall through to handle the remaining double words (32-bit chunks) */
bssWords:
xorl %eax, %eax /* fill memory with 0 */
movl %edx, %ecx /* move # quad bytes into ECX (for rep) */
andl $0x3, %ecx /* only need to zero at most 3 quad bytes */
cld
rep
stosl /* zero memory per 4 bytes */
#else /* !CONFIG_SSE */
/* clear out BSS double words (32-bits at a time) */
xorl %eax, %eax /* fill memory with 0 */
cld
rep
stosl /* zero memory per 4 bytes */
#endif /* CONFIG_SSE */
ret
#ifdef CONFIG_XIP
_x86_data_copy:
/* EDI = dest, ESI = source, ECX = size in 32-bit chunks */
#ifdef CONFIG_SSE
/* copy 16 bytes at a time using XMM until < 16 bytes remain */
movl %ecx ,%edx /* save number of quad bytes */
shrl $2, %ecx /* How many 16 bytes? */
je dataWords
dataDQ:
movdqu (%esi), %xmm0
movdqu %xmm0, (%edi)
addl $16, %esi
addl $16, %edi
loop dataDQ
dataWords:
movl %edx, %ecx /* restore # quad bytes */
andl $0x3, %ecx /* only need to copy at most 3 quad bytes */
#endif /* CONFIG_SSE */
rep
movsl /* copy data 4 bytes at a time */
ret
#endif /* CONFIG_XIP */
#if defined(CONFIG_SSE)
/* SSE control & status register initial value */