mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson
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bc8b57f08c
Directives such as .long and .word do not magically cause the
assembler location counter to become aligned in gas. As a result,
using these directives in code sections can result in misaligned
data words when building a Thumb-2 kernel (CONFIG_THUMB2_KERNEL).
This is a Bad Thing, since the ABI permits the compiler to assume
that fundamental types of word size or above are word- aligned when
accessing them from C. If the data is not really word-aligned,
this can cause impaired performance and stray alignment faults in
some circumstances.
In general, the following rules should be applied when using data
word declaration directives inside code sections:
* .quad and .double:
.align 3
* .long, .word, .single, .float:
.align (or .align 2)
* .short:
No explicit alignment required, since Thumb-2
instructions are always 2 or 4 bytes in size.
immediately after an instruction.
Reviewed-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Dave Martin <dave.martin@linaro.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
88 lines
1.3 KiB
ArmAsm
88 lines
1.3 KiB
ArmAsm
/*
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* relocate_kernel.S - put the kernel image in place to boot
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*/
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#include <asm/kexec.h>
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.globl relocate_new_kernel
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relocate_new_kernel:
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ldr r0,kexec_indirection_page
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ldr r1,kexec_start_address
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/*
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* If there is no indirection page (we are doing crashdumps)
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* skip any relocation.
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*/
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cmp r0, #0
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beq 2f
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0: /* top, read another word for the indirection page */
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ldr r3, [r0],#4
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/* Is it a destination page. Put destination address to r4 */
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tst r3,#1,0
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beq 1f
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bic r4,r3,#1
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b 0b
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1:
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/* Is it an indirection page */
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tst r3,#2,0
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beq 1f
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bic r0,r3,#2
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b 0b
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1:
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/* are we done ? */
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tst r3,#4,0
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beq 1f
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b 2f
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1:
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/* is it source ? */
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tst r3,#8,0
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beq 0b
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bic r3,r3,#8
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mov r6,#1024
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9:
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ldr r5,[r3],#4
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str r5,[r4],#4
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subs r6,r6,#1
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bne 9b
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b 0b
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2:
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/* Jump to relocated kernel */
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mov lr,r1
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mov r0,#0
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ldr r1,kexec_mach_type
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ldr r2,kexec_boot_atags
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mov pc,lr
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.align
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.globl kexec_start_address
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kexec_start_address:
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.long 0x0
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.globl kexec_indirection_page
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kexec_indirection_page:
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.long 0x0
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.globl kexec_mach_type
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kexec_mach_type:
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.long 0x0
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/* phy addr of the atags for the new kernel */
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.globl kexec_boot_atags
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kexec_boot_atags:
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.long 0x0
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relocate_new_kernel_end:
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.globl relocate_new_kernel_size
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relocate_new_kernel_size:
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.long relocate_new_kernel_end - relocate_new_kernel
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