RE: [PATCH v2]arm64:move elfcorehdr reservation early for crash dump kernel

-----Original Message-----
From: Poonam Aggrwal <redacted>
Sent: Monday, December 30, 2019 2:01 PM
To: takahiro.akashi@linaro.org; linux-arm-kernel@lists.infradead.org
Cc: Nikhil Gupta <redacted>; Poonam Aggrwal
[off-list ref]
Subject: [PATCH v2]arm64:move elfcorehdr reservation early for crash dump
kernel

on some SOCs, elfcorehdr address may overlap with the address of reserved
memory allocated using early_init_fdt_scan_reserved_mem

Reviewed-by: Prabhakar Kushwaha <redacted>
Signed-off-by: Poonam Aggrwal <redacted>
---
Overlaps seen on LS1043A SoC:
[    0.000000] Reserved memory: created DMA memory pool at
0x00000000f7c00000, size 4 MiB
[    0.000000] OF: reserved mem: initialized node qman-fqd, compatible id
shared-dma-pool
[    0.000000] Reserved memory: created DMA memory pool at
0x00000000f4000000, size 32 MiB
[    0.000000] OF: reserved mem: initialized node qman-pfdr, compatible id
shared-dma-pool
[    0.000000] Reserved memory: created DMA memory pool at
0x00000000f6000000, size 16 MiB
[    0.000000] OF: reserved mem: initialized node bman-fbpr, compatible id
shared-dma-pool
[    0.000000] Reserving 1KB of memory at 0xf7fff000 for elfcorehdr

panic in elfcorehdr_read:
[    0.443984] Unable to handle kernel paging request at virtual address
ffff000037fff000
[    0.451942] Mem abort info:
[    0.454740]   ESR = 0x96000006
[    0.457806]   EC = 0x25: DABT (current EL), IL = 32 bits
[    0.463142]   SET = 0, FnV = 0
[    0.466202]   EA = 0, S1PTW = 0
[    0.469353] Data abort info:
[    0.472243]   ISV = 0, ISS = 0x00000006
[    0.476094]   CM = 0, WnR = 0
[    0.479072] swapper pgtable: 4k pages, 48-bit VAs,
pgdp=00000000d9373000
[    0.485806] [ffff000037fff000] pgd=00000000f7bf7003,
pud=00000000f7bf6003, pmd=0000000000000000
[    0.494553] Internal error: Oops: 96000006 [#1] PREEMPT SMP
[    0.500146] Modules linked in:
[    0.503211] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.5.0-rc3-00062-
gbf8d1cd #5
[    0.510725] Hardware name: LS1043A RDB Board (DT)
[    0.515446] pstate: 80000005 (Nzcv daif -PAN -UAO)
[    0.520260] pc : __memcpy+0x78/0x180
[    0.523847] lr : elfcorehdr_read+0x28/0x38
<snip>
[    0.611262] Call trace:
[    0.613713]  __memcpy+0x78/0x180
[    0.616950]  vmcore_init+0x70/0x534
 arch/arm64/mm/init.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index

b65dffd..e610180 100644

--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c

@@ -438,6 +438,8 @@ void __init arm64_memblock_init(void)
 		initrd_end = initrd_start + phys_initrd_size;
 	}

+	reserve_elfcorehdr();
+
 	early_init_fdt_scan_reserved_mem();

 	if (IS_ENABLED(CONFIG_ZONE_DMA)) {

@@ -452,8 +454,6 @@ void __init arm64_memblock_init(void)

 	reserve_crashkernel();

-	reserve_elfcorehdr();
-
 	high_memory = __va(memblock_end_of_DRAM() - 1) + 1;

 	dma_contiguous_reserve(arm64_dma32_phys_limit);
--

2.7.4