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Commit 7d2471f9 authored by Kevin Hao's avatar Kevin Hao Committed by Scott Wood
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powerpc/fsl_booke: make sure PAGE_OFFSET map to memstart_addr for relocatable kernel 



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: default avatarKevin Hao <haokexin@gmail.com>
[scottwood@freescale.com: make offset long and non-negative in simple case]
Signed-off-by: default avatarScott Wood <scottwood@freescale.com>
parent 813125d8

arch/powerpc/kernel/head_fsl_booke.S

+69 −5
Original line number Diff line number Diff line
@@ -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.

arch/powerpc/mm/fsl_booke_mmu.c

+36 −6
Original line number Diff line number Diff line
@@ -231,7 +231,7 @@ void __init adjust_total_lowmem(void) 


	i = switch_to_as1();

	__max_low_memory = map_mem_in_cams(ram, CONFIG_LOWMEM_CAM_NUM);

	restore_to_as0(i);

	restore_to_as0(i, 0, 0);



	pr_info("Memory CAM mapping: ");

	for (i = 0; i < tlbcam_index - 1; i++)
@@ -252,17 +252,25 @@ void setup_initial_memory_limit(phys_addr_t first_memblock_base, 
}



#ifdef CONFIG_RELOCATABLE

notrace void __init relocate_init(phys_addr_t start)

int __initdata is_second_reloc;

notrace void __init relocate_init(u64 dt_ptr, phys_addr_t start)

{

	unsigned long base = KERNELBASE;



	kernstart_addr = start;

	if (is_second_reloc) {

		virt_phys_offset = PAGE_OFFSET - memstart_addr;

		return;

	}



	/*

	 * Relocatable kernel support based on processing of dynamic

	 * relocation entries.

	 * Compute the virt_phys_offset :

	 * relocation entries. Before we get the real memstart_addr,

	 * We will compute the virt_phys_offset like this:

	 * virt_phys_offset = stext.run - kernstart_addr

	 *

	 * stext.run = (KERNELBASE & ~0x3ffffff) + (kernstart_addr & 0x3ffffff)

	 * stext.run = (KERNELBASE & ~0x3ffffff) +

	 *				(kernstart_addr & 0x3ffffff)

	 * When we relocate, we have :

	 *

	 *	(kernstart_addr & 0x3ffffff) = (stext.run & 0x3ffffff)
@@ -272,10 +280,32 @@ notrace void __init relocate_init(phys_addr_t start) 
	 *                              (kernstart_addr & ~0x3ffffff)

	 *

	 */

	kernstart_addr = start;

	start &= ~0x3ffffff;

	base &= ~0x3ffffff;

	virt_phys_offset = base - start;

	early_get_first_memblock_info(__va(dt_ptr), NULL);

	/*

	 * We now get the memstart_addr, then we should check if this

	 * address is the same as what the PAGE_OFFSET map to now. If

	 * not we have to change the map of PAGE_OFFSET to memstart_addr

	 * and do a second relocation.

	 */

	if (start != memstart_addr) {

		int n;

		long offset = start - memstart_addr;



		is_second_reloc = 1;

		n = switch_to_as1();

		/* map a 64M area for the second relocation */

		if (memstart_addr > start)

			map_mem_in_cams(0x4000000, CONFIG_LOWMEM_CAM_NUM);

		else

			map_mem_in_cams_addr(start, PAGE_OFFSET + offset,

					0x4000000, CONFIG_LOWMEM_CAM_NUM);

		restore_to_as0(n, offset, __va(dt_ptr));

		/* We should never reach here */

		panic("Relocation error");

	}

}

#endif

#endif

arch/powerpc/mm/mmu_decl.h

+1 −1
Original line number Diff line number Diff line
@@ -149,7 +149,7 @@ extern void MMU_init_hw(void); 
extern unsigned long mmu_mapin_ram(unsigned long top);

extern void adjust_total_lowmem(void);

extern int switch_to_as1(void);

extern void restore_to_as0(int esel);

extern void restore_to_as0(int esel, int offset, void *dt_ptr);

#endif

extern void loadcam_entry(unsigned int index);