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

4 files changed, 45 insertions, 30 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);
diff --git a/arch/powerpc/platforms/powernv/opal-fadump.h b/arch/powerpc/platforms/powernv/opal-fadump.h
index e630cb0f108f..f1e9ecf548c5 100644
--- a/arch/powerpc/platforms/powernv/opal-fadump.h
+++ b/arch/powerpc/platforms/powernv/opal-fadump.h
@@ -27,9 +27,6 @@
  */
 #define OPAL_FADUMP_VERSION			0x1
 
-/* Maximum number of memory regions kernel supports */
-#define OPAL_FADUMP_MAX_MEM_REGS		128
-
 /*
  * OPAL FADump kernel metadata
  *
@@ -42,7 +39,7 @@ struct opal_fadump_mem_struct {
 	u16	region_cnt;		/* number of regions */
 	u16	registered_regions;	/* Regions registered for MPIPL */
 	u64	fadumphdr_addr;
-	struct opal_mpipl_region	rgn[OPAL_FADUMP_MAX_MEM_REGS];
+	struct opal_mpipl_region	rgn[FADUMP_MAX_MEM_REGS];
 } __packed;
 
 /*
diff --git a/arch/powerpc/platforms/pseries/rtas-fadump.c b/arch/powerpc/platforms/pseries/rtas-fadump.c
index a525180c1f0f..70c3013fdd07 100644
--- a/arch/powerpc/platforms/pseries/rtas-fadump.c
+++ b/arch/powerpc/platforms/pseries/rtas-fadump.c
@@ -42,7 +42,13 @@ static void rtas_fadump_update_config(struct fw_dump *fadump_conf,
 static void rtas_fadump_get_config(struct fw_dump *fadump_conf,
 				   const struct rtas_fadump_mem_struct *fdm)
 {
-	fadump_conf->boot_memory_size = be64_to_cpu(fdm->rmr_region.source_len);
+	fadump_conf->boot_mem_addr[0] =
+		be64_to_cpu(fdm->rmr_region.source_address);
+	fadump_conf->boot_mem_sz[0] = be64_to_cpu(fdm->rmr_region.source_len);
+	fadump_conf->boot_memory_size = fadump_conf->boot_mem_sz[0];
+
+	fadump_conf->boot_mem_top = fadump_conf->boot_memory_size;
+	fadump_conf->boot_mem_regs_cnt = 1;
 
 	/*
 	 * Start address of reserve dump area (permanent reservation) for
@@ -499,6 +505,9 @@ void __init rtas_fadump_dt_scan(struct fw_dump *fadump_conf, u64 node)
 	fadump_conf->ops		= &rtas_fadump_ops;
 	fadump_conf->fadump_supported	= 1;
 
+	/* Firmware supports 64-bit value for size, align it to pagesize. */
+	fadump_conf->max_copy_size = _ALIGN_DOWN(U64_MAX, PAGE_SIZE);
+
 	/*
 	 * The 'ibm,kernel-dump' rtas node is present only if there is
 	 * dump data waiting for us.
diff --git a/arch/powerpc/platforms/pseries/rtas-fadump.h b/arch/powerpc/platforms/pseries/rtas-fadump.h
index 6602ff69e10d..fd59bd7ca9c3 100644
--- a/arch/powerpc/platforms/pseries/rtas-fadump.h
+++ b/arch/powerpc/platforms/pseries/rtas-fadump.h
@@ -69,6 +69,11 @@ struct rtas_fadump_mem_struct {
 	/* Kernel dump sections */
 	struct rtas_fadump_section		cpu_state_data;
 	struct rtas_fadump_section		hpte_region;
+
+	/*
+	 * TODO: Extend multiple boot memory regions support in the kernel
+	 *       for this platform.
+	 */
 	struct rtas_fadump_section		rmr_region;
 };