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proc info

__FINIT	.text/* * Read processor ID register (CP#15, CR0), and look up in the linker-built * supported processor list.  Note that we can't use the absolute addresses * for the __proc_info lists since we aren't running with the MMU on * (and therefore, we are not in the correct address space).  We have to * calculate the offset. * *	r9 = cpuid * Returns: *	r3, r4, r6 corrupted *	r5 = proc_info pointer in physical address space *	r9 = cpuid (preserved) */__lookup_processor_type:	adr	r3, __lookup_processor_type_data @ r3 = __lookup_processor_type_data所在行物理地址，adr是基于PC寄存器计算地址值，	                                                @ 由于这时候还没有使能MMU，PC寄存器中使用的还是物理地址	ldmia	r3, {r4 - r6} @ [r3]->r4,[r3+4]->r5,[r3+8]->r6,                                                   @ r4 = __lookup_processor_type_data所在行的虚拟地址,r5 = __proc_info_begin(虚拟地址),r6 = __proc_info_end(虚拟地址)  	sub	r3, r3, r4			@ get offset between virt&phys,r3 = r3 - r7,即物理地址 - 虚拟地址	add	r5, r5, r3			@ convert virt addresses to,r5 = __proc_info_begin对应的物理地址	add	r6, r6, r3			@ physical address space,r6 = __proc_info_end对应的物理地址1:	ldmia	r5, {r3, r4}			@ value, mask,r3、r4=proc_info_list结构中的cpu_val、cpu_mask	and	r4, r4, r9			@ mask wanted bits,r9中保存的是从cp15的CR0读到的Main ID,r4 = cpu_mask & Main ID	teq	r3, r4                             @ 比较cpu_val与cpu_mask & Main ID	beq	2f				@ 如果相等，表示找到匹配的proc_info_list结构，地址就存于r5中，直接跳回	add	r5, r5, #PROC_INFO_SZ		@ sizeof(proc_info_list)@ 上一步没有找到，r5+PROC_INFO_SZ，试图匹配下一个info	cmp	r5, r6                             @ 与info end比较	blo	1b                                 @ 如果还没有比较到end处，继续跳回比较	mov	r5, #0				@ unknown processor，没有匹配到对应的processor，即没有找到proc_info_list结构2:	mov	pc, lrENDPROC(__lookup_processor_type)

NOTE：

/arch/arm/kernel/asm-offsets.c

DEFINE(PROC_INFO_SZ, sizeof(structproc_info_list));

/include/linux/kbuild.h

#define DEFINE(sym, val) \         asm volatile("\n->" #sym " %0 " #val : : "i" (val))

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