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Subject[UPDATED PATCH v2] powerpc32: Kexec support for PPC440X chipsets
Date
UPDATE: Minor update in Copyright assignment in misc_32.S
Added requirement of upstream kexec-tools.

Changes from v1: Uses a tmp mapping in the other address space to setup
the 1:1 mapping (suggested by Sebastian Andrzej Siewior).

Note 1: Should we do the same for kernel entry code for PPC44x ?

This patch adds kexec support for PPC440 based chipsets.This work is based
on the KEXEC patches for FSL BookE.

The FSL BookE patch and the code flow could be found at the link below:

http://patchwork.ozlabs.org/patch/49359/

Steps:

1) Invalidate all the TLB entries except the one this code is run from
2) Create a tmp mapping for our code in the other address space and jump to it
3) Invalidate the entry we used
4) Create a 1:1 mapping for 0-2GiB in blocks of 256M
5) Jump to the new 1:1 mapping and invalidate the tmp mapping

I have tested this patches on Ebony, Sequoia boards and Virtex on QEMU.
It would be great if somebody could test this on the other boards.

You need the latest snapshot of kexec-tools for ppc440x support, available at

git://git.kernel.org/pub/scm/utils/kernel/kexec/kexec-tools.git

Signed-off-by: Suzuki Poulose <suzuki@in.ibm.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
arch/powerpc/Kconfig | 2
arch/powerpc/include/asm/kexec.h | 2
arch/powerpc/kernel/misc_32.S | 171 ++++++++++++++++++++++++++++++++++++++
3 files changed, 173 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 423145a6..d04fae0 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -349,7 +349,7 @@ config ARCH_ENABLE_MEMORY_HOTREMOVE

config KEXEC
bool "kexec system call (EXPERIMENTAL)"
- depends on (PPC_BOOK3S || FSL_BOOKE) && EXPERIMENTAL
+ depends on (PPC_BOOK3S || FSL_BOOKE || (44x && !SMP && !47x)) && EXPERIMENTAL
help
kexec is a system call that implements the ability to shutdown your
current kernel, and to start another kernel. It is like a reboot
diff --git a/arch/powerpc/include/asm/kexec.h b/arch/powerpc/include/asm/kexec.h
index 8a33698..f921eb1 100644
--- a/arch/powerpc/include/asm/kexec.h
+++ b/arch/powerpc/include/asm/kexec.h
@@ -2,7 +2,7 @@
#define _ASM_POWERPC_KEXEC_H
#ifdef __KERNEL__

-#ifdef CONFIG_FSL_BOOKE
+#if defined(CONFIG_FSL_BOOKE) || defined(CONFIG_44x)

/*
* On FSL-BookE we setup a 1:1 mapping which covers the first 2GiB of memory
diff --git a/arch/powerpc/kernel/misc_32.S b/arch/powerpc/kernel/misc_32.S
index 998a100..f7d760a 100644
--- a/arch/powerpc/kernel/misc_32.S
+++ b/arch/powerpc/kernel/misc_32.S
@@ -8,6 +8,8 @@
* kexec bits:
* Copyright (C) 2002-2003 Eric Biederman <ebiederm@xmission.com>
* GameCube/ppc32 port Copyright (C) 2004 Albert Herranz
+ * PPC44x port. Copyright (C) 2011, IBM Corporation
+ * Author: Suzuki Poulose <suzuki@in.ibm.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
@@ -736,6 +738,175 @@ relocate_new_kernel:
mr r5, r31

li r0, 0
+#elif defined(CONFIG_44x) && !defined(CONFIG_47x)
+
+/*
+ * Code for setting up 1:1 mapping for PPC440x for KEXEC
+ *
+ * We cannot switch off the MMU on PPC44x.
+ * So we:
+ * 1) Invalidate all the mappings except the one we are running from.
+ * 2) Create a tmp mapping for our code in the other address space(TS) and
+ * jump to it. Invalidate the entry we started in.
+ * 3) Create a 1:1 mapping for 0-2GiB in chunks of 256M in original TS.
+ * 4) Jump to the 1:1 mapping in original TS.
+ * 5) Invalidate the tmp mapping.
+ *
+ * - Based on the kexec support code for FSL BookE
+ * - Doesn't support 47x yet.
+ *
+ */
+ /* Save our parameters */
+ mr r29, r3
+ mr r30, r4
+ mr r31, r5
+
+ /* Load our MSR_IS and TID to MMUCR for TLB search */
+ mfspr r3,SPRN_PID
+ mfmsr r4
+ andi. r4,r4,MSR_IS@l
+ beq wmmucr
+ oris r3,r3,PPC44x_MMUCR_STS@h
+wmmucr:
+ mtspr SPRN_MMUCR,r3
+ sync
+
+ /*
+ * Invalidate all the TLB entries except the current entry
+ * where we are running from
+ */
+ bl 0f /* Find our address */
+0: mflr r5 /* Make it accessible */
+ tlbsx r23,0,r5 /* Find entry we are in */
+ li r4,0 /* Start at TLB entry 0 */
+ li r3,0 /* Set PAGEID inval value */
+1: cmpw r23,r4 /* Is this our entry? */
+ beq skip /* If so, skip the inval */
+ tlbwe r3,r4,PPC44x_TLB_PAGEID /* If not, inval the entry */
+skip:
+ addi r4,r4,1 /* Increment */
+ cmpwi r4,64 /* Are we done? */
+ bne 1b /* If not, repeat */
+ isync
+
+ /* Create a temp mapping and jump to it */
+ andi. r6, r23, 1 /* Find the index to use */
+ addi r24, r6, 1 /* r24 will contain 1 or 2 */
+
+ mfmsr r9 /* get the MSR */
+ rlwinm r5, r9, 27, 31, 31 /* Extract the MSR[IS] */
+ xori r7, r5, 1 /* Use the other address space */
+
+ /* Read the current mapping entries */
+ tlbre r3, r23, PPC44x_TLB_PAGEID
+ tlbre r4, r23, PPC44x_TLB_XLAT
+ tlbre r5, r23, PPC44x_TLB_ATTRIB
+
+ /* Save our current XLAT entry */
+ mr r25, r4
+
+ /* Extract the TLB PageSize */
+ li r10, 1 /* r10 will hold PageSize */
+ rlwinm r11, r3, 0, 24, 27 /* bits 24-27 */
+
+ /* XXX: As of now we use 256M, 4K pages */
+ cmpwi r11, PPC44x_TLB_256M
+ bne tlb_4k
+ rotlwi r10, r10, 28 /* r10 = 256M */
+ b write_out
+tlb_4k:
+ cmpwi r11, PPC44x_TLB_4K
+ bne default
+ rotlwi r10, r10, 12 /* r10 = 4K */
+ b write_out
+default:
+ rotlwi r10, r10, 10 /* r10 = 1K */
+
+write_out:
+ /*
+ * Write out the tmp 1:1 mapping for this code in other address space
+ * Fixup EPN = RPN , TS=other address space
+ */
+ insrwi r3, r7, 1, 23 /* Bit 23 is TS for PAGEID field */
+
+ /* Write out the tmp mapping entries */
+ tlbwe r3, r24, PPC44x_TLB_PAGEID
+ tlbwe r4, r24, PPC44x_TLB_XLAT
+ tlbwe r5, r24, PPC44x_TLB_ATTRIB
+
+ subi r11, r10, 1 /* PageOffset Mask = PageSize - 1 */
+ not r10, r11 /* Mask for PageNum */
+
+ /* Switch to other address space in MSR */
+ insrwi r9, r7, 1, 26 /* Set MSR[IS] = r7 */
+
+ bl 1f
+1: mflr r8
+ addi r8, r8, (2f-1b) /* Find the target offset */
+
+ /* Jump to the tmp mapping */
+ mtspr SPRN_SRR0, r8
+ mtspr SPRN_SRR1, r9
+ rfi
+
+2:
+ /* Invalidate the entry we were executing from */
+ li r3, 0
+ tlbwe r3, r23, PPC44x_TLB_PAGEID
+
+ /* attribute fields. rwx for SUPERVISOR mode */
+ li r5, 0
+ ori r5, r5, (PPC44x_TLB_SW | PPC44x_TLB_SR | PPC44x_TLB_SX | PPC44x_TLB_G)
+
+ /* Create 1:1 mapping in 256M pages */
+ xori r7, r7, 1 /* Revert back to Original TS */
+
+ li r8, 0 /* PageNumber */
+ li r6, 3 /* TLB Index, start at 3 */
+
+next_tlb:
+ rotlwi r3, r8, 28 /* Create EPN (bits 0-3) */
+ mr r4, r3 /* RPN = EPN */
+ ori r3, r3, (PPC44x_TLB_VALID | PPC44x_TLB_256M) /* SIZE = 256M, Valid */
+ insrwi r3, r7, 1, 23 /* Set TS from r7 */
+
+ tlbwe r3, r6, PPC44x_TLB_PAGEID /* PageID field : EPN, V, SIZE */
+ tlbwe r4, r6, PPC44x_TLB_XLAT /* Address translation : RPN */
+ tlbwe r5, r6, PPC44x_TLB_ATTRIB /* Attributes */
+
+ addi r8, r8, 1 /* Increment PN */
+ addi r6, r6, 1 /* Increment TLB Index */
+ cmpwi r8, 8 /* Are we done ? */
+ bne next_tlb
+ isync
+
+ /* Jump to the new mapping 1:1 */
+ li r9,0
+ insrwi r9, r7, 1, 26 /* Set MSR[IS] = r7 */
+
+ bl 1f
+1: mflr r8
+ and r8, r8, r11 /* Get our offset within page */
+ addi r8, r8, (2f-1b)
+
+ and r5, r25, r10 /* Get our target PageNum */
+ or r8, r8, r5 /* Target jump address */
+
+ mtspr SPRN_SRR0, r8
+ mtspr SPRN_SRR1, r9
+ rfi
+2:
+ /* Invalidate the tmp entry we used */
+ li r3, 0
+ tlbwe r3, r24, PPC44x_TLB_PAGEID
+ sync
+
+ /* Restore the parameters */
+ mr r3, r29
+ mr r4, r30
+ mr r5, r31
+
+ li r0, 0
#else
li r0, 0



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