arch/powerpc/kernel/reloc_32.S

Source file repositories/reference/linux-study-clean/arch/powerpc/kernel/reloc_32.S

File Facts

System
Linux kernel
Corpus path
arch/powerpc/kernel/reloc_32.S
Extension
.S
Size
5349 bytes
Lines
206
Domain
Architecture Layer
Bucket
arch/powerpc
Inferred role
Architecture Layer: arch/powerpc
Status
atlas-only

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

#include <asm/ppc_asm.h>

/* Dynamic section table entry tags */
DT_RELA = 7			/* Tag for Elf32_Rela section */
DT_RELASZ = 8			/* Size of the Rela relocs */
DT_RELAENT = 9			/* Size of one Rela reloc entry */

STN_UNDEF = 0			/* Undefined symbol index */
STB_LOCAL = 0			/* Local binding for the symbol */

R_PPC_ADDR16_LO = 4		/* Lower half of (S+A) */
R_PPC_ADDR16_HI = 5		/* Upper half of (S+A) */
R_PPC_ADDR16_HA = 6		/* High Adjusted (S+A) */
R_PPC_RELATIVE = 22

/*
 * r3 = desired final address
 */

_GLOBAL(relocate)

	mflr	r0		/* Save our LR */
	bcl	20,31,$+4	/* Find our current runtime address */
0:	mflr	r12		/* Make it accessible */
	mtlr	r0

	lwz	r11, (p_dyn - 0b)(r12)
	add	r11, r11, r12	/* runtime address of .dynamic section */
	lwz	r9, (p_rela - 0b)(r12)
	add	r9, r9, r12	/* runtime address of .rela.dyn section */
	lwz	r10, (p_st - 0b)(r12)
	add	r10, r10, r12	/* runtime address of _stext section */
	lwz	r13, (p_sym - 0b)(r12)
	add	r13, r13, r12	/* runtime address of .dynsym section */

	/*
	 * Scan the dynamic section for RELA, RELASZ entries
	 */
	li	r6, 0
	li	r7, 0
	li	r8, 0
1:	lwz	r5, 0(r11)	/* ELF_Dyn.d_tag */
	cmpwi	r5, 0		/* End of ELF_Dyn[] */
	beq	eodyn
	cmpwi	r5, DT_RELA
	bne	relasz
	lwz	r7, 4(r11)	/* r7 = rela.link */
	b	skip
relasz:
	cmpwi	r5, DT_RELASZ
	bne	relaent
	lwz	r8, 4(r11)	/* r8 = Total Rela relocs size */
	b	skip
relaent:
	cmpwi	r5, DT_RELAENT
	bne	skip
	lwz	r6, 4(r11)	/* r6 = Size of one Rela reloc */
skip:
	addi	r11, r11, 8
	b	1b
eodyn:				/* End of Dyn Table scan */

	/* Check if we have found all the entries */
	cmpwi	r7, 0
	beq	done
	cmpwi	r8, 0
	beq	done
	cmpwi	r6, 0
	beq	done

Annotation

Implementation Notes