This is based on the codes in head_44x.S. With this patch the kernel
can only boot from 0 with CONFIG_RELOCATABLE enabled. We will add the
support to boot from a non 0 address in the following patches.
Signed-off-by: Kevin Hao <haoke...@gmail.com>
---
arch/powerpc/Kconfig | 2 +-
arch/powerpc/include/asm/page.h | 2 +-
arch/powerpc/kernel/head_32.S | 103 +++++++++++++++++++++++++++++++++
arch/powerpc/kernel/prom_init_check.sh | 2 +-
4 files changed, 106 insertions(+), 3 deletions(-)
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index c33e3ad..8fe2792 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -866,7 +866,7 @@ config DYNAMIC_MEMSTART
config RELOCATABLE
bool "Build a relocatable kernel"
- depends on ADVANCED_OPTIONS && FLATMEM && 44x
+ depends on ADVANCED_OPTIONS && FLATMEM && (44x || 6xx)
select NONSTATIC_KERNEL
help
This builds a kernel image that is capable of running at the
diff --git a/arch/powerpc/include/asm/page.h b/arch/powerpc/include/asm/page.h
index 988c812..7145c14 100644
--- a/arch/powerpc/include/asm/page.h
+++ b/arch/powerpc/include/asm/page.h
@@ -207,7 +207,7 @@ extern long long virt_phys_offset;
* On non-Book-E PPC64 PAGE_OFFSET and MEMORY_START are constants so use
* the other definitions for __va & __pa.
*/
-#ifdef CONFIG_BOOKE
+#if defined(CONFIG_BOOKE) || defined(CONFIG_6xx)
#define __va(x) ((void *)(unsigned long)((phys_addr_t)(x) + VIRT_PHYS_OFFSET))
#define __pa(x) ((unsigned long)(x) - VIRT_PHYS_OFFSET)
#else
diff --git a/arch/powerpc/kernel/head_32.S b/arch/powerpc/kernel/head_32.S
index dc0488b..eb47b13 100644
--- a/arch/powerpc/kernel/head_32.S
+++ b/arch/powerpc/kernel/head_32.S
@@ -73,6 +73,8 @@ _ENTRY(_start);
nop /* used by __secondary_hold on prep (mtx) and chrp smp */
nop
+ bl perform_relocation
+
/* PMAC
* Enter here with the kernel text, data and bss loaded starting at
* 0, running with virtual == physical mapping.
@@ -149,6 +151,8 @@ __start:
*/
bl early_init
+ bl after_relocation_init
+
/* Switch MMU off, clear BATs and flush TLB. At this point, r3 contains
* the physical address we are running at, returned by early_init()
*/
@@ -180,6 +184,7 @@ __after_mmu_off:
#endif /* CONFIG_6xx */
+#ifndef CONFIG_RELOCATABLE
/*
* We need to run with _start at physical address 0.
* On CHRP, we are loaded at 0x10000 since OF on CHRP uses
@@ -193,6 +198,8 @@ __after_mmu_off:
lis r5,PHYSICAL_START@h
cmplw 0,r4,r5 /* already running at PHYSICAL_START? */
bne relocate_kernel
+#endif
+
/*
* we now have the 1st 16M of ram mapped with the bats.
* prep needs the mmu to be turned on here, but pmac already has it on.
@@ -1263,6 +1270,102 @@ m8260_gorom:
blr
#endif
+perform_relocation:
+#ifdef CONFIG_RELOCATABLE
+/*
+ * Relocate ourselves to the current runtime address.
+ * This is called only by the Boot CPU.
+ * r21 will be loaded with the physical runtime address of _stext
+ * Save the r3~r7 since these registers may contain the values needed
+ * by the following boot code.
+ */
+ mr r22,r3
+ mr r23,r4
+ mr r24,r5
+ mr r25,r6
+ mr r26,r7
+
+ mflr r20
+ bl 0f /* Get our runtime address */
+0: mflr r21 /* Make it accessible */
+ addis r21,r21,(_stext - 0b)@ha
+ addi r21,r21,(_stext - 0b)@l /*Get our current runtime base*/
+
+ /*
+ * We have the runtime address of our base.
+ * We calculate our shift of offset from a 256M page.
+ * We could map the 256M page we belong to at PAGE_OFFSET and
+ * get going from there.
+ */
+ lis r4,KERNELBASE@h
+ ori r4,r4,KERNELBASE@l
+ rlwinm r6,r21,0,4,31 /* r6 = PHYS_START % 256M */
+ rlwinm r5,r4,0,4,31 /* r5 = KERNELBASE % 256M */
+ subf r3,r5,r6 /* r3 = r6 - r5 */
+ add r3,r4,r3 /* Required Virutal Address */
+
+ bl relocate
+ mtlr r20
+ mr r3,r22
+ mr r4,r23
+ mr r5,r24
+ mr r6,r25
+ mr r7,r26
+#endif
+ blr
+
+after_relocation_init:
+#ifdef CONFIG_RELOCATABLE
+ /*
+ * Relocatable kernel support based on processing of dynamic
+ * relocation entries.
+ *
+ * r21 will contain the current offset of _stext
+ */
+ lis r3,kernstart_addr@ha
+ la r3,kernstart_addr@l(r3)
+
+ /* Store kernstart_addr */
+ tophys(r3,r3)
+ stw r21,0(r3)
+
+ /*
+ * Compute the virt_phys_offset :
+ * virt_phys_offset = stext.run - kernstart_addr
+ *
+ * stext.run = (KERNELBASE & ~0xfffffff) + (kernstart_addr & 0xfffffff)
+ * When we relocate, we have :
+ *
+ * (kernstart_addr & 0xfffffff) = (stext.run & 0xfffffff)
+ *
+ * hence:
+ * virt_phys_offset = (KERNELBASE & ~0xfffffff)
+ * - (kernstart_addr & ~0xfffffff)
+ *
+ */
+
+ /* KERNELBASE&~0xfffffff => (r4,r5) */
+ lis r5,KERNELBASE@h
+ rlwinm r5,r5,0,0,3 /* Align to 256M, lower 32bit */
+
+ /* kernelstart_addr & ~0xfffffff => (r6,r7) */
+ rlwinm r7,r21,0,0,3 /* Align to 256M, lower 32bit */
+
+ /*
+ * 64bit subtraction.
+ */
+ subf r5,r7,r5
+
+ /* Store virt_phys_offset */
+ lis r3,virt_phys_offset@h
+ ori r3,r3,virt_phys_offset@l
+
+ tophys(r3,r3)
+ li r4,0
+ stw r4,0(r3) /* Higher 32bit */
+ stw r5,4(r3) /* Lower 32bit */
+#endif
+ blr
/*
* We put a few things here that have to be page-aligned.
diff --git a/arch/powerpc/kernel/prom_init_check.sh
b/arch/powerpc/kernel/prom_init_check.sh
index 3765da6..a24c208 100644
--- a/arch/powerpc/kernel/prom_init_check.sh
+++ b/arch/powerpc/kernel/prom_init_check.sh
@@ -22,7 +22,7 @@ __secondary_hold_acknowledge __secondary_hold_spinloop __start
strcmp strcpy strlcpy strlen strncmp strstr logo_linux_clut224
reloc_got2 kernstart_addr memstart_addr linux_banner _stext
opal_query_takeover opal_do_takeover opal_enter_rtas opal_secondary_entry
-boot_command_line __prom_init_toc_start __prom_init_toc_end"
+boot_command_line __prom_init_toc_start __prom_init_toc_end virt_phys_offset"
NM="$1"
OBJ="$2"
--
1.8.1.4
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