From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from va3outboundpool.messaging.microsoft.com (va3ehsobe002.messaging.microsoft.com [216.32.180.12]) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (Client CN "mail.global.frontbridge.com", Issuer "MSIT Machine Auth CA 2" (not verified)) by ozlabs.org (Postfix) with ESMTPS id 067FE2C064D for ; Fri, 28 Jun 2013 05:58:47 +1000 (EST) Date: Thu, 27 Jun 2013 14:58:34 -0500 From: Scott Wood Subject: Re: [PATCH 1/2] powerpc: enable the relocatable support for the fsl booke 32bit kernel To: Kevin Hao In-Reply-To: <1372298434-20220-2-git-send-email-haokexin@gmail.com> (from haokexin@gmail.com on Wed Jun 26 21:00:33 2013) Message-ID: <1372363114.8183.54@snotra> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; delsp=Yes; format=Flowed Cc: linuxppc List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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? > @@ -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 > #elif defined(ENTRY_MAPPING_KEXEC_SETUP) > /* > diff --git a/arch/powerpc/kernel/head_fsl_booke.S =20 > b/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 =20 > address */ > +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? > @@ -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=