[PATCH 2/3] powerpc/fadump: align destination address to pagesize

[Hari Bathini]

On crash, boot memory area is copied to a destination address by f/w.
This region is setup as separate PT_LOAD segment with appropriate
offset to handle the different physical address and offset in vmcore.
If this destination address is not page aligned, reading the vmcore
with mmap is likely to fail forcing tools like makedumpfile to fall
back to regular read. Avoid mmap read failure by ensuring that the
destination address is always page aligned.

Signed-off-by: Hari Bathini <hbathini at linux.ibm.com>
---
 arch/powerpc/kernel/fadump.c                 | 5 +++++
 arch/powerpc/platforms/pseries/rtas-fadump.c | 6 ++++++
 2 files changed, 11 insertions(+)

diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
index dc2350b288cf..ee564e8226b1 100644
--- a/arch/powerpc/kernel/fadump.c
+++ b/arch/powerpc/kernel/fadump.c
@@ -365,6 +365,11 @@ static unsigned long __init get_fadump_area_size(void)
 
 	size += fw_dump.cpu_state_data_size;
 	size += fw_dump.hpte_region_size;
+	/*
+	 * Account for pagesize alignment of boot memory area destination address.
+	 * This faciliates in mmap reading of first kernel's memory.
+	 */
+	size = PAGE_ALIGN(size);
 	size += fw_dump.boot_memory_size;
 	size += sizeof(struct fadump_crash_info_header);
 	size += sizeof(struct elfhdr); /* ELF core header.*/
diff --git a/arch/powerpc/platforms/pseries/rtas-fadump.c b/arch/powerpc/platforms/pseries/rtas-fadump.c
index 35f9cb602c30..764df25304bd 100644
--- a/arch/powerpc/platforms/pseries/rtas-fadump.c
+++ b/arch/powerpc/platforms/pseries/rtas-fadump.c
@@ -108,6 +108,12 @@ static u64 rtas_fadump_init_mem_struct(struct fw_dump *fadump_conf)
 	fdm.hpte_region.destination_address = cpu_to_be64(addr);
 	addr += fadump_conf->hpte_region_size;
 
+	/*
+	 * Align boot memory area destination address to page boundary to
+	 * be able to mmap read this area in the vmcore.
+	 */
+	addr = PAGE_ALIGN(addr);
+
 	/* RMA region section */
 	fdm.rmr_region.request_flag = cpu_to_be32(RTAS_FADUMP_REQUEST_FLAG);
 	fdm.rmr_region.source_data_type =
-- 
2.35.1