powerpc: Process dynamic relocations for kernel (9c5f7d39) · Commits · 戴 / test

arch/powerpc/Kconfig

+24 −17

Original line number	Diff line number	Diff line
		@@ -847,23 +847,30 @@ config DYNAMIC_MEMSTART
		load address. When this option is enabled, the compile time physical
		address CONFIG_PHYSICAL_START is ignored.

		# Mapping based RELOCATABLE is moved to DYNAMIC_MEMSTART
		# config RELOCATABLE
		# bool "Build a relocatable kernel (EXPERIMENTAL)"
		# depends on EXPERIMENTAL && ADVANCED_OPTIONS && FLATMEM && (FSL_BOOKE \|\| PPC_47x)
		# help
		# This builds a kernel image that is capable of running at the
		# location the kernel is loaded at, without any alignment restrictions.
		#
		# One use is for the kexec on panic case where the recovery kernel
		# must live at a different physical address than the primary
		# kernel.
		#
		# Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
		# it has been loaded at and the compile time physical addresses
		# CONFIG_PHYSICAL_START is ignored. However CONFIG_PHYSICAL_START
		# setting can still be useful to bootwrappers that need to know the
		# load location of the kernel (eg. u-boot/mkimage).
		This option is overridden by CONFIG_RELOCATABLE

		config RELOCATABLE
		bool "Build a relocatable kernel (EXPERIMENTAL)"
		depends on EXPERIMENTAL && ADVANCED_OPTIONS && FLATMEM
		select NONSTATIC_KERNEL
		help
		This builds a kernel image that is capable of running at the
		location the kernel is loaded at, without any alignment restrictions.
		This feature is a superset of DYNAMIC_MEMSTART and hence overrides it.

		One use is for the kexec on panic case where the recovery kernel
		must live at a different physical address than the primary
		kernel.

		Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
		it has been loaded at and the compile time physical addresses
		CONFIG_PHYSICAL_START is ignored. However CONFIG_PHYSICAL_START
		setting can still be useful to bootwrappers that need to know the
		load address of the kernel (eg. u-boot/mkimage).

		config RELOCATABLE_PPC32
		def_bool y
		depends on PPC32 && RELOCATABLE

		config PAGE_OFFSET_BOOL
		bool "Set custom page offset address"

arch/powerpc/Makefile

+3 −3

Original line number	Diff line number	Diff line
		@@ -63,9 +63,9 @@ override CC += -m$(CONFIG_WORD_SIZE)
		override AR := GNUTARGET=elf$(CONFIG_WORD_SIZE)-powerpc $(AR)
		endif

		LDFLAGS_vmlinux-yy := -Bstatic
		LDFLAGS_vmlinux-$(CONFIG_PPC64)$(CONFIG_RELOCATABLE) := -pie
		LDFLAGS_vmlinux := $(LDFLAGS_vmlinux-yy)
		LDFLAGS_vmlinux-y := -Bstatic
		LDFLAGS_vmlinux-$(CONFIG_RELOCATABLE) := -pie
		LDFLAGS_vmlinux := $(LDFLAGS_vmlinux-y)

		CFLAGS-$(CONFIG_PPC64) := -mminimal-toc -mtraceback=no -mcall-aixdesc
		CFLAGS-$(CONFIG_PPC32) := -ffixed-r2 -mmultiple

arch/powerpc/kernel/Makefile

+2 −0

Original line number	Diff line number	Diff line
		@@ -85,6 +85,8 @@ extra-$(CONFIG_FSL_BOOKE) := head_fsl_booke.o
		extra-$(CONFIG_8xx) := head_8xx.o
		extra-y += vmlinux.lds

		obj-$(CONFIG_RELOCATABLE_PPC32) += reloc_32.o

		obj-$(CONFIG_PPC32) += entry_32.o setup_32.o
		obj-$(CONFIG_PPC64) += dma-iommu.o iommu.o
		obj-$(CONFIG_KGDB) += kgdb.o

arch/powerpc/kernel/reloc_32.S

0 → 100644

+208 −0

Original line number	Diff line number	Diff line
		/*
		* Code to process dynamic relocations for PPC32.
		*
		* Copyrights (C) IBM Corporation, 2011.
		* Author: Suzuki Poulose <suzuki@in.ibm.com>
		*
		* - Based on ppc64 code - reloc_64.S
		*
		* This program is free software; you can redistribute it and/or
		* modify it under the terms of the GNU General Public License
		* as published by the Free Software Foundation; either version
		* 2 of the License, or (at your option) any later version.
		*/

		#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 */
		bl 0f /* 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


		/*
		* Work out the current offset from the link time address of .rela
		* section.
		* cur_offset[r7] = rela.run[r9] - rela.link [r7]
		* _stext.link[r12] = _stext.run[r10] - cur_offset[r7]
		* final_offset[r3] = _stext.final[r3] - _stext.link[r12]
		*/
		subf r7, r7, r9 /* cur_offset */
		subf r12, r7, r10
		subf r3, r12, r3 /* final_offset */

		subf r8, r6, r8 /* relaz -= relaent */
		/*
		* Scan through the .rela table and process each entry
		* r9 - points to the current .rela table entry
		* r13 - points to the symbol table
		*/

		/*
		* Check if we have a relocation based on symbol
		* r5 will hold the value of the symbol.
		*/
		applyrela:
		lwz r4, 4(r9) /* r4 = rela.r_info */
		srwi r5, r4, 8 /* ELF32_R_SYM(r_info) */
		cmpwi r5, STN_UNDEF /* sym == STN_UNDEF ? */
		beq get_type /* value = 0 */
		/* Find the value of the symbol at index(r5) */
		slwi r5, r5, 4 /* r5 = r5 * sizeof(Elf32_Sym) */
		add r12, r13, r5 /* r12 = &__dyn_sym[Index] */

		/*
		* GNU ld has a bug, where dynamic relocs based on
		* STB_LOCAL symbols, the value should be assumed
		* to be zero. - Alan Modra
		*/
		/* XXX: Do we need to check if we are using GNU ld ? */
		lbz r5, 12(r12) /* r5 = dyn_sym[Index].st_info */
		extrwi r5, r5, 4, 24 /* r5 = ELF32_ST_BIND(r5) */
		cmpwi r5, STB_LOCAL /* st_value = 0, ld bug */
		beq get_type /* We have r5 = 0 */
		lwz r5, 4(r12) /* r5 = __dyn_sym[Index].st_value */

		get_type:
		/* Load the relocation type to r4 */
		extrwi r4, r4, 8, 24 /* r4 = ELF32_R_TYPE(r_info) = ((char)r4)[3] /

		/* R_PPC_RELATIVE */
		cmpwi r4, R_PPC_RELATIVE
		bne hi16
		lwz r4, 0(r9) /* r_offset */
		lwz r0, 8(r9) /* r_addend */
		add r0, r0, r3 /* final addend */
		stwx r0, r4, r7 /* memory[r4+r7]) = (u32)r0 */
		b nxtrela /* continue */

		/* R_PPC_ADDR16_HI */
		hi16:
		cmpwi r4, R_PPC_ADDR16_HI
		bne ha16
		lwz r4, 0(r9) /* r_offset */
		lwz r0, 8(r9) /* r_addend */
		add r0, r0, r3
		add r0, r0, r5 /* r0 = (S+A+Offset) */
		extrwi r0, r0, 16, 0 /* r0 = (r0 >> 16) */
		b store_half

		/* R_PPC_ADDR16_HA */
		ha16:
		cmpwi r4, R_PPC_ADDR16_HA
		bne lo16
		lwz r4, 0(r9) /* r_offset */
		lwz r0, 8(r9) /* r_addend */
		add r0, r0, r3
		add r0, r0, r5 /* r0 = (S+A+Offset) */
		extrwi r5, r0, 1, 16 /* Extract bit 16 */
		extrwi r0, r0, 16, 0 /* r0 = (r0 >> 16) */
		add r0, r0, r5 /* Add it to r0 */
		b store_half

		/* R_PPC_ADDR16_LO */
		lo16:
		cmpwi r4, R_PPC_ADDR16_LO
		bne nxtrela
		lwz r4, 0(r9) /* r_offset */
		lwz r0, 8(r9) /* r_addend */
		add r0, r0, r3
		add r0, r0, r5 /* r0 = (S+A+Offset) */
		extrwi r0, r0, 16, 16 /* r0 &= 0xffff */
		/* Fall through to */

		/* Store half word */
		store_half:
		sthx r0, r4, r7 /* memory[r4+r7] = (u16)r0 */

		nxtrela:
		/*
		* We have to flush the modified instructions to the
		* main storage from the d-cache. And also, invalidate the
		* cached instructions in i-cache which has been modified.
		*
		* We delay the sync / isync operation till the end, since
		* we won't be executing the modified instructions until
		* we return from here.
		*/
		dcbst r4,r7
		sync /* Ensure the data is flushed before icbi */
		icbi r4,r7
		cmpwi r8, 0 /* relasz = 0 ? */
		ble done
		add r9, r9, r6 /* move to next entry in the .rela table */
		subf r8, r6, r8 /* relasz -= relaent */
		b applyrela

		done:
		sync /* Wait for the flush to finish */
		isync /* Discard prefetched instructions */
		blr

		p_dyn: .long __dynamic_start - 0b
		p_rela: .long __rela_dyn_start - 0b
		p_sym: .long __dynamic_symtab - 0b
		p_st: .long _stext - 0b

arch/powerpc/kernel/vmlinux.lds.S

+7 −1

Original line number	Diff line number	Diff line
		@@ -170,7 +170,13 @@ SECTIONS
		}
		#ifdef CONFIG_RELOCATABLE
		. = ALIGN(8);
		.dynsym : AT(ADDR(.dynsym) - LOAD_OFFSET) { *(.dynsym) }
		.dynsym : AT(ADDR(.dynsym) - LOAD_OFFSET)
		{
		#ifdef CONFIG_RELOCATABLE_PPC32
		__dynamic_symtab = .;
		#endif
		*(.dynsym)
		}
		.dynstr : AT(ADDR(.dynstr) - LOAD_OFFSET) { *(.dynstr) }
		.dynamic : AT(ADDR(.dynamic) - LOAD_OFFSET)
		{

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