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author | Suzuki Poulose <suzuki@in.ibm.com> | 2011-12-14 22:59:24 +0000 |
---|---|---|
committer | Josh Boyer <jwboyer@gmail.com> | 2011-12-20 10:21:57 -0500 |
commit | 26ecb6c44bb33afc62905ba01b636dde70fc2dc6 (patch) | |
tree | 1e2a12510dcc81b40705ed04a1f4e1470856b041 /arch/powerpc/kernel | |
parent | 368ff8f14d6ed8e9fd3b7c2156f2607719bf5a7a (diff) | |
download | op-kernel-dev-26ecb6c44bb33afc62905ba01b636dde70fc2dc6.zip op-kernel-dev-26ecb6c44bb33afc62905ba01b636dde70fc2dc6.tar.gz |
powerpc/44x: Enable CONFIG_RELOCATABLE for PPC44x
The following patch adds relocatable kernel support - based on processing
of dynamic relocations - for PPC44x kernel.
We find the runtime address of _stext and relocate ourselves based
on the following calculation.
virtual_base = ALIGN(KERNELBASE,256M) +
MODULO(_stext.run,256M)
relocate() is called with the Effective Virtual Base Address (as
shown below)
| Phys. Addr| Virt. Addr |
Page (256M) |------------------------|
Boundary | | |
| | |
| | |
Kernel Load |___________|_ __ _ _ _ _|<- Effective
Addr(_stext)| | ^ |Virt. Base Addr
| | | |
| | | |
| |reloc_offset|
| | | |
| | | |
| |______v_____|<-(KERNELBASE)%256M
| | |
| | |
| | |
Page(256M) |-----------|------------|
Boundary | | |
The virt_phys_offset is updated accordingly, i.e,
virt_phys_offset = effective. kernel virt base - kernstart_addr
I have tested the patches on 440x platforms only. However this should
work fine for PPC_47x also, as we only depend on the runtime address
and the current TLB XLAT entry for the startup code, which is available
in r25. I don't have access to a 47x board yet. So, it would be great if
somebody could test this on 47x.
Signed-off-by: Suzuki K. Poulose <suzuki@in.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Kumar Gala <galak@kernel.crashing.org>
Cc: Tony Breeds <tony@bakeyournoodle.com>
Cc: Josh Boyer <jwboyer@gmail.com>
Cc: linuxppc-dev <linuxppc-dev@lists.ozlabs.org>
Signed-off-by: Josh Boyer <jwboyer@gmail.com>
Diffstat (limited to 'arch/powerpc/kernel')
-rw-r--r-- | arch/powerpc/kernel/head_44x.S | 95 |
1 files changed, 93 insertions, 2 deletions
diff --git a/arch/powerpc/kernel/head_44x.S b/arch/powerpc/kernel/head_44x.S index 0878bf5..7dd2981 100644 --- a/arch/powerpc/kernel/head_44x.S +++ b/arch/powerpc/kernel/head_44x.S @@ -64,6 +64,35 @@ _ENTRY(_start); mr r31,r3 /* save device tree ptr */ li r24,0 /* CPU number */ +#ifdef CONFIG_RELOCATABLE +/* + * Relocate ourselves to the current runtime address. + * This is called only by the Boot CPU. + * "relocate" is called with our current runtime virutal + * address. + * r21 will be loaded with the physical runtime address of _stext + */ + 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 (virutal) 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 +#endif + bl init_cpu_state /* @@ -86,7 +115,64 @@ _ENTRY(_start); bl early_init -#ifdef CONFIG_DYNAMIC_MEMSTART +#ifdef CONFIG_RELOCATABLE + /* + * Relocatable kernel support based on processing of dynamic + * relocation entries. + * + * r25 will contain RPN/ERPN for the start address of memory + * r21 will contain the current offset of _stext + */ + lis r3,kernstart_addr@ha + la r3,kernstart_addr@l(r3) + + /* + * Compute the kernstart_addr. + * kernstart_addr => (r6,r8) + * kernstart_addr & ~0xfffffff => (r6,r7) + */ + rlwinm r6,r25,0,28,31 /* ERPN. Bits 32-35 of Address */ + rlwinm r7,r25,0,0,3 /* RPN - assuming 256 MB page size */ + rlwinm r8,r21,0,4,31 /* r8 = (_stext & 0xfffffff) */ + or r8,r7,r8 /* Compute the lower 32bit of kernstart_addr */ + + /* Store kernstart_addr */ + stw r6,0(r3) /* higher 32bit */ + stw r8,4(r3) /* lower 32bit */ + + /* + * 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) */ + li r4, 0 /* higer 32bit */ + lis r5,KERNELBASE@h + rlwinm r5,r5,0,0,3 /* Align to 256M, lower 32bit */ + + /* + * 64bit subtraction. + */ + subfc r5,r7,r5 + subfe r4,r6,r4 + + /* Store virt_phys_offset */ + lis r3,virt_phys_offset@ha + la r3,virt_phys_offset@l(r3) + + stw r4,0(r3) + stw r5,4(r3) + +#elif defined(CONFIG_DYNAMIC_MEMSTART) /* * Mapping based, page aligned dynamic kernel loading. * @@ -804,7 +890,12 @@ skpinv: addi r4,r4,1 /* Increment */ /* * Configure and load pinned entry into TLB slot 63. */ -#ifdef CONFIG_DYNAMIC_MEMSTART +#ifdef CONFIG_NONSTATIC_KERNEL + /* + * In case of a NONSTATIC_KERNEL we reuse the TLB XLAT + * entries of the initial mapping set by the boot loader. + * The XLAT entry is stored in r25 + */ /* Read the XLAT entry for our current mapping */ tlbre r25,r23,PPC44x_TLB_XLAT |