[PATCH v21 4/8] arm64: kdump: add kdump support

On Wed, Jul 06, 2016 at 10:38:09AM -0700, Geoff Levand wrote:

On Wed, 2016-07-06 at 16:52 +0900, AKASHI Takahiro wrote:

quoted

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

@@ -136,6 +137,57 @@ static void __init reserve_crashkernel(void)
 }
 #endif /* CONFIG_KEXEC_CORE */
 
+#ifdef CONFIG_CRASH_DUMP
+static int __init early_init_dt_scan_elfcorehdr(unsigned long node,
+> 	> 	> const char *uname, int depth, void *data)
+{
+> 	> const __be32 *reg;
+> 	> int len;
+
+> 	> if (depth != 1 || strcmp(uname, "chosen") != 0)
+> 	> 	> return 0;
+
+> 	> reg = of_get_flat_dt_prop(node, "linux,elfcorehdr", &len);
+> 	> if (!reg || (len < (dt_root_addr_cells + dt_root_size_cells)))
+> 	> 	> return 1;
+
+> 	> elfcorehdr_addr = dt_mem_next_cell(dt_root_addr_cells, ??);
+> 	> elfcorehdr_size = dt_mem_next_cell(dt_root_size_cells, ??);
+
+> 	> return 1;
+}
+
+/*
+ * reserve_elfcorehdr() - reserves memory for elf core header
+ *
+ * This function reserves elf core header given in "elfcorehdr=" kernel
+ * command line parameter. This region contains all the information about
+ * primary kernel's core image and is used by a dump capture kernel to
+ * access the system memory on primary kernel.
+ */
+static void __init reserve_elfcorehdr(void)
+{

It seems like you could get rid of all these conditionals by
just putting this here:

	if (!IS_ENABLED(CONFIG_CRASH_DUMP))
		return;

Add this to reserve_elfcorehdr()?
Unfortunately, it won't work because this function accesses
elfcorehdr_addr & elfcorehdr_size which are defined only
if CONFIG_CRASH_DUMP.

Thanks,
-Takahiro AKASHI

quoted

+> 	> of_scan_flat_dt(early_init_dt_scan_elfcorehdr, NULL);
+
+> 	> if (!elfcorehdr_size)
+> 	> 	> return;
+
+> 	> if (memblock_is_region_reserved(elfcorehdr_addr, elfcorehdr_size)) {
+> 	> 	> pr_warn("elfcorehdr is overlapped\n");
+> 	> 	> return;
+> 	> }
+
+> 	> memblock_reserve(elfcorehdr_addr, elfcorehdr_size);
+
+> 	> pr_info("Reserving %lldKB of memory at 0x%llx for elfcorehdr\n",
+> 	> 	> elfcorehdr_size >> 10, elfcorehdr_addr);
+}
+#else
+static void __init reserve_elfcorehdr(void)
+{
+> 	> ;
+}
+#endif /* CONFIG_CRASH_DUMP */
 /*
  * Return the maximum physical address for ZONE_DMA (DMA_BIT_MASK(32)). It
  * currently assumes that for memory starting above 4G, 32-bit devices will

@@ -389,6 +441,8 @@ void __init arm64_memblock_init(void)
 
 > 	> reserve_crashkernel();
 
+> 	> reserve_elfcorehdr();
+
 > 	> early_init_fdt_scan_reserved_mem();
 
 > 	> /* 4GB maximum for 32-bit only capable devices */