linux-kernel - [PATCH v3] powerpc: Force page alignment for initrd reserved memory

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Date:	Sat, 21 May 2011 11:05:27 -0600
From:	Dave Carroll <dcarroll@...ekcorp.com>
To:	'Milton Miller' <miltonm@....com>,
	"Benjamin Herrenschmidt (E-mail)" <benh@...nel.crashing.org>
CC:	Paul Mackerras <paulus@...ba.org>,
	LPPC <linuxppc-dev@...ts.ozlabs.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH v3] powerpc: Force page alignment for initrd reserved memory


When using 64K pages with a separate cpio rootfs, U-Boot will align
the rootfs on a 4K page boundary. When the memory is reserved, and
subsequent early memblock_alloc is called, it will allocate memory
between the 64K page alignment and reserved memory. When the reserved
memory is subsequently freed, it is done so by pages, causing the
early memblock_alloc requests to be re-used, which in my case, caused
the device-tree to be clobbered.

This patch forces the reserved memory for initrd to be kernel page
aligned, and adds the same range extension when freeing initrd.


Signed-off-by: Dave Carroll <dcarroll@...ekcorp.com>
---
 arch/powerpc/kernel/prom.c |    4 +++-
 arch/powerpc/mm/init_32.c  |    3 +++
 arch/powerpc/mm/init_64.c  |    3 +++
 3 files changed, 9 insertions(+), 1 deletions(-)

diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
index 48aeb55..397d4a0 100644
--- a/arch/powerpc/kernel/prom.c
+++ b/arch/powerpc/kernel/prom.c
@@ -555,7 +555,9 @@ static void __init early_reserve_mem(void)
 #ifdef CONFIG_BLK_DEV_INITRD
        /* then reserve the initrd, if any */
        if (initrd_start && (initrd_end > initrd_start))
-               memblock_reserve(__pa(initrd_start), initrd_end - initrd_start);
+               memblock_reserve(_ALIGN_DOWN(__pa(initrd_start), PAGE_SIZE),
+                       _ALIGN_UP(initrd_end, PAGE_SIZE) -
+                       _ALIGN_DOWN(initrd_start, PAGE_SIZE));
 #endif /* CONFIG_BLK_DEV_INITRD */

 #ifdef CONFIG_PPC32
diff --git a/arch/powerpc/mm/init_32.c b/arch/powerpc/mm/init_32.c
index d65b591..b0791cb 100644
--- a/arch/powerpc/mm/init_32.c
+++ b/arch/powerpc/mm/init_32.c
@@ -226,6 +226,9 @@ void free_initmem(void)
 #ifdef CONFIG_BLK_DEV_INITRD
 void free_initrd_mem(unsigned long start, unsigned long end)
 {
+       start = _ALIGN_DOWN(start, PAGE_SIZE);
+       end = _ALIGN_UP(end, PAGE_SIZE);
+
        if (start < end)
                printk ("Freeing initrd memory: %ldk freed\n", (end - start) >> 10);
        for (; start < end; start += PAGE_SIZE) {
diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c
index 6374b21..07ae936 100644
--- a/arch/powerpc/mm/init_64.c
+++ b/arch/powerpc/mm/init_64.c
@@ -102,6 +102,9 @@ void free_initmem(void)
 #ifdef CONFIG_BLK_DEV_INITRD
 void free_initrd_mem(unsigned long start, unsigned long end)
 {
+       start = _ALIGN_DOWN(start, PAGE_SIZE);
+       end = _ALIGN_UP(end, PAGE_SIZE);
+
        if (start < end)
                printk ("Freeing initrd memory: %ldk freed\n", (end - start) >> 10);
        for (; start < end; start += PAGE_SIZE) {
--
1.7.4
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