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powerpc/fsl_booke: make sure PAGE_OFFSET map to memstart_addr for relocatable kernel

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This is always true for a non-relocatable kernel. Otherwise the kernel
would get stuck. But for a relocatable kernel, it seems a little
complicated. When booting a relocatable kernel, we just align the
kernel start addr to 64M and map the PAGE_OFFSET from there. The
relocation will base on this virtual address. But if this address
is not the same as the memstart_addr, we will have to change the
map of PAGE_OFFSET to the real memstart_addr and do another relocation
again.

Signed-off-by: Kevin Hao <haokexin@gmail.com>
[scottwood@freescale.com: make offset long and non-negative in simple case]
Signed-off-by: Scott Wood <scottwood@freescale.com>
This commit is contained in:
Kevin Hao
2013-12-24 15:12:10 +08:00
committed by Scott Wood
parent 813125d833
commit 7d2471f9fa
3 changed files with 106 additions and 12 deletions
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74
arch/powerpc/kernel/head_fsl_booke.S
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@@ -81,6 +81,39 @@ _ENTRY(_start);
mr r23,r3
mr r25,r4
bl 0f
0: mflr r8
addis r3,r8,(is_second_reloc - 0b)@ha
lwz r19,(is_second_reloc - 0b)@l(r3)
/* Check if this is the second relocation. */
cmpwi r19,1
bne 1f
/*
* For the second relocation, we already get the real memstart_addr
* from device tree. So we will map PAGE_OFFSET to memstart_addr,
* then the virtual address of start kernel should be:
* PAGE_OFFSET + (kernstart_addr - memstart_addr)
* Since the offset between kernstart_addr and memstart_addr should
* never be beyond 1G, so we can just use the lower 32bit of them
* for the calculation.
*/
lis r3,PAGE_OFFSET@h
addis r4,r8,(kernstart_addr - 0b)@ha
addi r4,r4,(kernstart_addr - 0b)@l
lwz r5,4(r4)
addis r6,r8,(memstart_addr - 0b)@ha
addi r6,r6,(memstart_addr - 0b)@l
lwz r7,4(r6)
subf r5,r7,r5
add r3,r3,r5
b 2f
1:
/*
* We have the runtime (virutal) address of our base.
* We calculate our shift of offset from a 64M page.
@@ -94,7 +127,14 @@ _ENTRY(_start);
subf r3,r5,r6 /* r3 = r6 - r5 */
add r3,r4,r3 /* Required Virtual Address */
bl relocate
2: bl relocate
/*
* For the second relocation, we already set the right tlb entries
* for the kernel space, so skip the code in fsl_booke_entry_mapping.S
*/
cmpwi r19,1
beq set_ivor
#endif
/* We try to not make any assumptions about how the boot loader
@@ -122,6 +162,7 @@ _ENTRY(__early_start)
#include "fsl_booke_entry_mapping.S"
#undef ENTRY_MAPPING_BOOT_SETUP
set_ivor:
/* Establish the interrupt vector offsets */
SET_IVOR(0, CriticalInput);
SET_IVOR(1, MachineCheck);
@@ -207,11 +248,13 @@ _ENTRY(__early_start)
bl early_init
#ifdef CONFIG_RELOCATABLE
mr r3,r30
mr r4,r31
#ifdef CONFIG_PHYS_64BIT
mr r3,r23
mr r4,r25
mr r5,r23
mr r6,r25
#else
mr r3,r25
mr r5,r25
#endif
bl relocate_init
#endif
@@ -1207,6 +1250,9 @@ _GLOBAL(switch_to_as1)
/*
* Restore to the address space 0 and also invalidate the tlb entry created
* by switch_to_as1.
* r3 - the tlb entry which should be invalidated
* r4 - __pa(PAGE_OFFSET in AS1) - __pa(PAGE_OFFSET in AS0)
* r5 - device tree virtual address. If r4 is 0, r5 is ignored.
*/
_GLOBAL(restore_to_as0)
mflr r0
@@ -1215,7 +1261,15 @@ _GLOBAL(restore_to_as0)
0: mflr r9
addi r9,r9,1f - 0b
mfmsr r7
/*
* We may map the PAGE_OFFSET in AS0 to a different physical address,
* so we need calculate the right jump and device tree address based
* on the offset passed by r4.
*/
add r9,r9,r4
add r5,r5,r4
2: mfmsr r7
li r8,(MSR_IS | MSR_DS)
andc r7,r7,r8
@@ -1234,9 +1288,19 @@ _GLOBAL(restore_to_as0)
mtspr SPRN_MAS1,r9
tlbwe
isync
cmpwi r4,0
bne 3f
mtlr r0
blr
/*
* The PAGE_OFFSET will map to a different physical address,
* jump to _start to do another relocation again.
*/
3: mr r3,r5
bl _start
/*
* We put a few things here that have to be page-aligned. This stuff
* goes at the beginning of the data segment, which is page-aligned.