Re: [PATCH 1/2] powerpc: enable the relocatable support for the fsl booke 32bit kernel
From: Scott Wood <hidden>
Date: 2013-06-27 19:58:47
On 06/26/2013 09:00:33 PM, Kevin Hao wrote:
This is based on the codes in the head_44x.S. Since we always align to 256M before mapping the PAGE_OFFSET for a relocatable kernel, we also change the init tlb map to 256M size.
Why 256M? This tightens the alignment requirement for dynamic memstart. And what =20 about boards with less than 256 MiB of RAM?
quoted hunk ↗ jump to hunk
@@ -176,6 +176,8 @@ skpinv: addi r6,r6,1 =20/* Increment */ /* 7. Jump to KERNELBASE mapping */ lis r6,(KERNELBASE & ~0xfff)@h ori r6,r6,(KERNELBASE & ~0xfff)@l + rlwinm r7,r25,0,4,31 + add r6,r7,r6
Please consider using the more readable form of rlwinm/rlwimi: rlwinm r7,r25,0,0x0fffffff
quoted hunk ↗ jump to hunk
#elif defined(ENTRY_MAPPING_KEXEC_SETUP) /*diff --git a/arch/powerpc/kernel/head_fsl_booke.S =20b/arch/powerpc/kernel/head_fsl_booke.S index d10a7ca..c3b4c8e53 100644--- a/arch/powerpc/kernel/head_fsl_booke.S +++ b/arch/powerpc/kernel/head_fsl_booke.S@@ -83,10 +83,43 @@ _ENTRY(_start); andc r31,r20,r18 /* r31 =3D page base */ or r31,r31,r19 /* r31 =3D devtree phys addr */ mfspr r30,SPRN_MAS7 - - li r25,0 /* phys kernel start (low) */ li r24,0 /* CPU number */ - li r23,0 /* phys kernel start (high) */ + +#ifdef CONFIG_RELOCATABLE + bl 0f /* Get our runtime =20address */ +0: mflr r3 /* Make it accessible */ + addis r3,r3,(_stext - 0b)@ha + addi r3,r3,(_stext - 0b)@l /* Get our current runtime base =20 */ + + /* Translate _stext address to physical, save in r23/r25 */ + tlbsx 0,r3 /* must succeed */ + + mfspr r16,SPRN_MAS1 + mfspr r20,SPRN_MAS3 + rlwinm r17,r16,25,0x1f /* r17 =3D log2(page size) */ + li r18,1024 + slw r18,r18,r17 /* r18 =3D page size */ + addi r18,r18,-1 + and r19,r3,r18 /* r19 =3D page offset */ + andc r25,r20,r18 /* r25 =3D page base */ + or r25,r25,r19 /* r25 =3D _stext phys addr */ + mfspr r23,SPRN_MAS7
This duplicates the code for finding the device tree physical =20 address... maybe factor it out into a function?
quoted hunk ↗ jump to hunk
@@ -197,7 +230,58 @@ _ENTRY(__early_start)=20 bl early_init =20 -#ifdef CONFIG_DYNAMIC_MEMSTART +#ifdef CONFIG_RELOCATABLE + /* + * Relocatable kernel support based on processing of dynamic + * relocation entries. + * + * r25/r23 will contain RPN/ERPN for the start address of memory
The start of memory or the start of the kernel?
+ */ + lis r3,kernstart_addr@ha + la r3,kernstart_addr@l(r3) + +#ifdef CONFIG_PHYS_64BIT + stw r23,0(r3) + stw r25,4(r3) +#else + stw r25,0(r3) +#endif
This part looks the same for relocatable and dynamic memstart -- can =20 you avoid duplicating?
+ /* + * Compute the virt_phys_offset : + * virt_phys_offset =3D stext.run - kernstart_addr + * + * stext.run =3D (KERNELBASE & ~0xfffffff) + (kernstart_addr & =20 0xfffffff) + * When we relocate, we have : + * + * (kernstart_addr & 0xfffffff) =3D (stext.run & 0xfffffff) + * + * hence: + * virt_phys_offset =3D (KERNELBASE & ~0xfffffff) - + * (kernstart_addr & ~0xfffffff) + * + */ + + /* KERNELBASE&~0xfffffff =3D> (r4,r5) */
+ li r4, 0 /* higer 32bit */ + lis r5,KERNELBASE@h
Please be consistent with whitespace. -Scott=