powerpc/fadump: support holes in kernel boot memory area

With support to copy multiple kernel boot memory regions owing to copy
size limitation, also handle holes in the memory area to be preserved.
Support as many as 128 kernel boot memory regions. This allows having
an adequate FADump capture kernel size for different scenarios.

Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/156821385448.5656.6124791213910877759.stgit@hbathini.in.ibm.com

1 files changed, 29 insertions, 25 deletions

diff --git a/arch/powerpc/platforms/powernv/opal-fadump.c b/arch/powerpc/platforms/powernv/opal-fadump.c
index 006648e4d5e6..d361d37d975f 100644
--- a/arch/powerpc/platforms/powernv/opal-fadump.c
+++ b/arch/powerpc/platforms/powernv/opal-fadump.c
@@ -115,19 +115,28 @@ static void opal_fadump_update_config(struct fw_dump *fadump_conf,
 static void opal_fadump_get_config(struct fw_dump *fadump_conf,
 				   const struct opal_fadump_mem_struct *fdm)
 {
+	unsigned long base, size, last_end, hole_size;
 	int i;
 
 	if (!fadump_conf->dump_active)
 		return;
 
+	last_end = 0;
+	hole_size = 0;
 	fadump_conf->boot_memory_size = 0;
 
 	pr_debug("Boot memory regions:\n");
 	for (i = 0; i < fdm->region_cnt; i++) {
-		pr_debug("\t%d. base: 0x%llx, size: 0x%llx\n",
-			 (i + 1), fdm->rgn[i].src, fdm->rgn[i].size);
+		base = fdm->rgn[i].src;
+		size = fdm->rgn[i].size;
+		pr_debug("\t[%03d] base: 0x%lx, size: 0x%lx\n", i, base, size);
 
-		fadump_conf->boot_memory_size += fdm->rgn[i].size;
+		fadump_conf->boot_mem_addr[i] = base;
+		fadump_conf->boot_mem_sz[i] = size;
+		fadump_conf->boot_memory_size += size;
+		hole_size += (base - last_end);
+
+		last_end = base + size;
 	}
 
 	/*
@@ -160,6 +169,8 @@ static void opal_fadump_get_config(struct fw_dump *fadump_conf,
 		pr_warn("WARNING: If the unsaved regions contain kernel pages, the vmcore will be corrupted.\n");
 	}
 
+	fadump_conf->boot_mem_top = (fadump_conf->boot_memory_size + hole_size);
+	fadump_conf->boot_mem_regs_cnt = fdm->region_cnt;
 	opal_fadump_update_config(fadump_conf, fdm);
 }
 
@@ -174,33 +185,20 @@ static void opal_fadump_init_metadata(struct opal_fadump_mem_struct *fdm)
 
 static u64 opal_fadump_init_mem_struct(struct fw_dump *fadump_conf)
 {
-	int max_copy_size, cur_size, size;
-	u64 src_addr, dest_addr;
+	u64 addr = fadump_conf->reserve_dump_area_start;
+	int i;
 
 	opal_fdm = __va(fadump_conf->kernel_metadata);
 	opal_fadump_init_metadata(opal_fdm);
 
-	/*
-	 * Firmware supports 32-bit field for size. Align it to PAGE_SIZE
-	 * and request firmware to copy multiple kernel boot memory regions.
-	 */
-	max_copy_size = _ALIGN_DOWN(U32_MAX, PAGE_SIZE);
-
 	/* Boot memory regions */
-	src_addr = 0;
-	dest_addr = fadump_conf->reserve_dump_area_start;
-	size = fadump_conf->boot_memory_size;
-	while (size) {
-		cur_size = size > max_copy_size ? max_copy_size : size;
-
-		opal_fdm->rgn[opal_fdm->region_cnt].src  = src_addr;
-		opal_fdm->rgn[opal_fdm->region_cnt].dest = dest_addr;
-		opal_fdm->rgn[opal_fdm->region_cnt].size = cur_size;
+	for (i = 0; i < fadump_conf->boot_mem_regs_cnt; i++) {
+		opal_fdm->rgn[i].src	= fadump_conf->boot_mem_addr[i];
+		opal_fdm->rgn[i].dest	= addr;
+		opal_fdm->rgn[i].size	= fadump_conf->boot_mem_sz[i];
 
 		opal_fdm->region_cnt++;
-		dest_addr	+= cur_size;
-		src_addr	+= cur_size;
-		size		-= cur_size;
+		addr += fadump_conf->boot_mem_sz[i];
 	}
 
 	/*
@@ -212,7 +210,7 @@ static u64 opal_fadump_init_mem_struct(struct fw_dump *fadump_conf)
 
 	opal_fadump_update_config(fadump_conf, opal_fdm);
 
-	return dest_addr;
+	return addr;
 }
 
 static u64 opal_fadump_get_metadata_size(void)
@@ -254,7 +252,7 @@ static int opal_fadump_setup_metadata(struct fw_dump *fadump_conf)
 	 * by a kernel that intends to preserve crash'ed kernel's memory.
 	 */
 	ret = opal_mpipl_register_tag(OPAL_MPIPL_TAG_BOOT_MEM,
-				      fadump_conf->boot_memory_size);
+				      fadump_conf->boot_mem_top);
 	if (ret != OPAL_SUCCESS) {
 		pr_err("Failed to set boot memory tag!\n");
 		err = -EPERM;
@@ -670,6 +668,12 @@ void __init opal_fadump_dt_scan(struct fw_dump *fadump_conf, u64 node)
 	fadump_conf->fadump_supported	= 1;
 
 	/*
+	 * Firmware supports 32-bit field for size. Align it to PAGE_SIZE
+	 * and request firmware to copy multiple kernel boot memory regions.
+	 */
+	fadump_conf->max_copy_size = _ALIGN_DOWN(U32_MAX, PAGE_SIZE);
+
+	/*
 	 * Check if dump has been initiated on last reboot.
 	 */
 	prop = of_get_flat_dt_prop(dn, "mpipl-boot", NULL);