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| author | Nicolas Pitre <nicolas.pitre@linaro.org> | 2017-08-24 15:54:47 -0400 |
|---|---|---|
| committer | Nicolas Pitre <nicolas.pitre@linaro.org> | 2017-09-10 19:34:52 -0400 |
| commit | 9520b1a1b5f7a34888e14de3cf2ee0ee5344e9fe (patch) | |
| tree | 08d9c67e778a425d93af10bbaad866f61f447b1f /arch/arm/kernel/head-common.S | |
| parent | 569dbb88e80deb68974ef6fdd6a13edb9d686261 (diff) | |
| download | linux-9520b1a1b5f7a34888e14de3cf2ee0ee5344e9fe.tar.bz2 | |
ARM: head-common.S: speed up startup code
Let's use optimized routines such as memcpy to copy .data and memzero
to clear .bss in the startup code instead of doing it one word at a
time. Those routines don't use any global data so they're safe to use
even if .data and .bss segments are not initialized.
In the .data copy case a temporary stack is installed in the .bss area
as the actual kernel stack is located within the copied data area. The
XIP kernel linker script ensures a 8 byte alignment for that purpose.
Finally, make the .data copy and related pointers surrounded by
CONFIG_XIP_KERNEL to make it obvious what it is all about. This will
allow for further cleanups in the non-XIP linker script.
Signed-off-by: Nicolas Pitre <nico@linaro.org>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: Chris Brandt <Chris.Brandt@renesas.com>
Diffstat (limited to 'arch/arm/kernel/head-common.S')
| -rw-r--r-- | arch/arm/kernel/head-common.S | 76 |
1 files changed, 44 insertions, 32 deletions
diff --git a/arch/arm/kernel/head-common.S b/arch/arm/kernel/head-common.S index 8733012d231f..bf9c4e38eced 100644 --- a/arch/arm/kernel/head-common.S +++ b/arch/arm/kernel/head-common.S @@ -79,47 +79,59 @@ ENDPROC(__vet_atags) */ __INIT __mmap_switched: - adr r3, __mmap_switched_data - - ldmia r3!, {r4, r5, r6, r7} - cmp r4, r5 @ Copy data segment if needed -1: cmpne r5, r6 - ldrne fp, [r4], #4 - strne fp, [r5], #4 - bne 1b - - mov fp, #0 @ Clear BSS (and zero fp) -1: cmp r6, r7 - strcc fp, [r6],#4 - bcc 1b - - ARM( ldmia r3, {r4, r5, r6, r7, sp}) - THUMB( ldmia r3, {r4, r5, r6, r7} ) - THUMB( ldr sp, [r3, #16] ) - str r9, [r4] @ Save processor ID - str r1, [r5] @ Save machine type - str r2, [r6] @ Save atags pointer - cmp r7, #0 - strne r0, [r7] @ Save control register values + + mov r7, r1 + mov r8, r2 + mov r10, r0 + + adr r4, __mmap_switched_data + mov fp, #0 + +#ifdef CONFIG_XIP_KERNEL + ARM( ldmia r4!, {r0, r1, r2, sp} ) + THUMB( ldmia r4!, {r0, r1, r2, r3} ) + THUMB( mov sp, r3 ) + sub r2, r2, r1 + bl memcpy @ copy .data to RAM +#endif + + ARM( ldmia r4!, {r0, r1, sp} ) + THUMB( ldmia r4!, {r0, r1, r3} ) + THUMB( mov sp, r3 ) + sub r1, r1, r0 + bl __memzero @ clear .bss + + ldmia r4, {r0, r1, r2, r3} + str r9, [r0] @ Save processor ID + str r7, [r1] @ Save machine type + str r8, [r2] @ Save atags pointer + cmp r3, #0 + strne r10, [r3] @ Save control register values b start_kernel ENDPROC(__mmap_switched) .align 2 .type __mmap_switched_data, %object __mmap_switched_data: - .long __data_loc @ r4 - .long _sdata @ r5 - .long __bss_start @ r6 - .long _end @ r7 - .long processor_id @ r4 - .long __machine_arch_type @ r5 - .long __atags_pointer @ r6 +#ifdef CONFIG_XIP_KERNEL + .long _sdata @ r0 + .long __data_loc @ r1 + .long _edata_loc @ r2 + .long __bss_stop @ sp (temporary stack in .bss) +#endif + + .long __bss_start @ r0 + .long __bss_stop @ r1 + .long init_thread_union + THREAD_START_SP @ sp + + .long processor_id @ r0 + .long __machine_arch_type @ r1 + .long __atags_pointer @ r2 #ifdef CONFIG_CPU_CP15 - .long cr_alignment @ r7 + .long cr_alignment @ r3 #else - .long 0 @ r7 + .long 0 @ r3 #endif - .long init_thread_union + THREAD_START_SP @ sp .size __mmap_switched_data, . - __mmap_switched_data /* |