[PATCH v2 0/3] powerpc/fadump: pass additional args to dump capture kernel

[PATCH v2 0/3] powerpc/fadump: pass additional args to dump capture kernel

[Hari Bathini]

While fadump is a more reliable alternative to kdump dump capturing
method, it doesn't support passing additional parameters. Having
such support is desirable for two major reasons:

  1. It helps minimize the memory consumption of fadump dump capture
     kernel by disabling features that consume considerable amount of
     memory but have little significance for dump capture environment
     (eg. numa, cma, cgroup, etc.)
   2. It helps disable such features/components in dump capture kernel
      that are unstable and/or are being debugged.

This patch series is a follow-up to [1]. Adds support for passing
additional parameters to fadump capture kernel to make it more
desirable. For this, a dedicated area is passed between production
kernel and capture kerenl to pass these additional parameters. This
support is enabled only on pseries as of now. The dedicated area is
referred to as RTAS_FADUMP_PARAM_AREA.

In radix MMU mode, this dedicated area can be anywhere but in case of
hash MMU, it can only be in the first memory block to be accessible
during early boot. Enabling this feature support in both radix and
hash MMU modes but in hash MMU only when RMA size is 768MB or more
to avoid complex memory real estate with FW components.

The first patch adds support for multiple boot memory regions to make
addition of any new region types simpler. The second patch sets up the
parameter (dedicated) area to be passed to the capture kernel.
/sys/kernel/fadump/bootargs_append is exported to the userspace to
specify the additional parameters to be passed to the capture kernel.
The last patch appends the parameters to bootargs during capture
kernel boot.

Changes in v2:
* RFC tag removed.
* Moved variable declaration out of switch case.
* Zero'ed the parameter area while setting up.
* Reserving the parameter area only when needed.

[1] https://lore.kernel.org/linuxppc-dev/20231205201835.388030-1-hbathini@linux.ibm.com/

Hari Bathini (3):
  powerpc/pseries/fadump: add support for multiple boot memory regions
  powerpc/fadump: setup additional parameters for dump capture kernel
  powerpc/fadump: pass additional parameters when fadump is active

 arch/powerpc/include/asm/fadump-internal.h   |   5 +-
 arch/powerpc/include/asm/fadump.h            |   2 +
 arch/powerpc/kernel/fadump.c                 | 149 ++++++++--
 arch/powerpc/kernel/prom.c                   |   3 +
 arch/powerpc/platforms/powernv/opal-fadump.c |  13 +-
 arch/powerpc/platforms/pseries/rtas-fadump.c | 290 +++++++++++++------
 arch/powerpc/platforms/pseries/rtas-fadump.h |  29 +-
 7 files changed, 366 insertions(+), 125 deletions(-)

-- 
2.45.0

[PATCH v2 1/3] powerpc/pseries/fadump: add support for multiple boot memory regions

[Hari Bathini]

Currently, fadump on pseries assumes a single boot memory region even
though f/w supports more than one boot memory region. Add support for
more boot memory regions to make the implementation flexible for any
enhancements that introduce other region types. For this, rtas memory
structure for fadump is updated to have multiple boot memory regions
instead of just one. Additionally, methods responsible for creating
the fadump memory structure during both the first and second kernel
boot have been modified to take these multiple boot memory regions
into account. Also, a new callback has been added to the fadump_ops
structure to get the maximum boot memory regions supported by the
platform.

Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
---
 arch/powerpc/include/asm/fadump-internal.h   |   2 +-
 arch/powerpc/kernel/fadump.c                 |  27 +-
 arch/powerpc/platforms/powernv/opal-fadump.c |   7 +
 arch/powerpc/platforms/pseries/rtas-fadump.c | 255 +++++++++++++------
 arch/powerpc/platforms/pseries/rtas-fadump.h |  26 +-
 5 files changed, 197 insertions(+), 120 deletions(-)

diff --git a/arch/powerpc/include/asm/fadump-internal.h b/arch/powerpc/include/asm/fadump-internal.h
index 5d706a7acc8a..35787fa1ac60 100644
--- a/arch/powerpc/include/asm/fadump-internal.h
+++ b/arch/powerpc/include/asm/fadump-internal.h
@@ -156,6 +156,7 @@ struct fadump_ops {
 				      struct seq_file *m);
 	void	(*fadump_trigger)(struct fadump_crash_info_header *fdh,
 				  const char *msg);
+	int	(*fadump_max_boot_mem_rgns)(void);
 };
 
 /* Helper functions */
@@ -163,7 +164,6 @@ s32 __init fadump_setup_cpu_notes_buf(u32 num_cpus);
 void fadump_free_cpu_notes_buf(void);
 u32 *__init fadump_regs_to_elf_notes(u32 *buf, struct pt_regs *regs);
 void __init fadump_update_elfcore_header(char *bufp);
-bool is_fadump_boot_mem_contiguous(void);
 bool is_fadump_reserved_mem_contiguous(void);
 
 #else /* !CONFIG_PRESERVE_FA_DUMP */
diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
index 0b849563393e..fe6be00451b9 100644
--- a/arch/powerpc/kernel/fadump.c
+++ b/arch/powerpc/kernel/fadump.c
@@ -220,28 +220,6 @@ static bool is_fadump_mem_area_contiguous(u64 d_start, u64 d_end)
 	return ret;
 }
 
-/*
- * Returns true, if there are no holes in boot memory area,
- * false otherwise.
- */
-bool is_fadump_boot_mem_contiguous(void)
-{
-	unsigned long d_start, d_end;
-	bool ret = false;
-	int i;
-
-	for (i = 0; i < fw_dump.boot_mem_regs_cnt; i++) {
-		d_start = fw_dump.boot_mem_addr[i];
-		d_end   = d_start + fw_dump.boot_mem_sz[i];
-
-		ret = is_fadump_mem_area_contiguous(d_start, d_end);
-		if (!ret)
-			break;
-	}
-
-	return ret;
-}
-
 /*
  * Returns true, if there are no holes in reserved memory area,
  * false otherwise.
@@ -381,10 +359,11 @@ static unsigned long __init get_fadump_area_size(void)
 static int __init add_boot_mem_region(unsigned long rstart,
 				      unsigned long rsize)
 {
+	int max_boot_mem_rgns = fw_dump.ops->fadump_max_boot_mem_rgns();
 	int i = fw_dump.boot_mem_regs_cnt++;
 
-	if (fw_dump.boot_mem_regs_cnt > FADUMP_MAX_MEM_REGS) {
-		fw_dump.boot_mem_regs_cnt = FADUMP_MAX_MEM_REGS;
+	if (fw_dump.boot_mem_regs_cnt > max_boot_mem_rgns) {
+		fw_dump.boot_mem_regs_cnt = max_boot_mem_rgns;
 		return 0;
 	}
 
diff --git a/arch/powerpc/platforms/powernv/opal-fadump.c b/arch/powerpc/platforms/powernv/opal-fadump.c
index 767a6b19e42a..5a88d7efb48a 100644
--- a/arch/powerpc/platforms/powernv/opal-fadump.c
+++ b/arch/powerpc/platforms/powernv/opal-fadump.c
@@ -599,6 +599,12 @@ static void opal_fadump_trigger(struct fadump_crash_info_header *fdh,
 		pr_emerg("No backend support for MPIPL!\n");
 }
 
+/* FADUMP_MAX_MEM_REGS or lower */
+static int opal_fadump_max_boot_mem_rgns(void)
+{
+	return FADUMP_MAX_MEM_REGS;
+}
+
 static struct fadump_ops opal_fadump_ops = {
 	.fadump_init_mem_struct		= opal_fadump_init_mem_struct,
 	.fadump_get_metadata_size	= opal_fadump_get_metadata_size,
@@ -611,6 +617,7 @@ static struct fadump_ops opal_fadump_ops = {
 	.fadump_process			= opal_fadump_process,
 	.fadump_region_show		= opal_fadump_region_show,
 	.fadump_trigger			= opal_fadump_trigger,
+	.fadump_max_boot_mem_rgns	= opal_fadump_max_boot_mem_rgns,
 };
 
 void __init opal_fadump_dt_scan(struct fw_dump *fadump_conf, u64 node)
diff --git a/arch/powerpc/platforms/pseries/rtas-fadump.c b/arch/powerpc/platforms/pseries/rtas-fadump.c
index 214f37788b2d..4db78b2bb2a8 100644
--- a/arch/powerpc/platforms/pseries/rtas-fadump.c
+++ b/arch/powerpc/platforms/pseries/rtas-fadump.c
@@ -29,9 +29,6 @@ static const struct rtas_fadump_mem_struct *fdm_active;
 static void rtas_fadump_update_config(struct fw_dump *fadump_conf,
 				      const struct rtas_fadump_mem_struct *fdm)
 {
-	fadump_conf->boot_mem_dest_addr =
-		be64_to_cpu(fdm->rmr_region.destination_address);
-
 	fadump_conf->fadumphdr_addr = (fadump_conf->boot_mem_dest_addr +
 				       fadump_conf->boot_memory_size);
 }
@@ -43,20 +40,53 @@ static void rtas_fadump_update_config(struct fw_dump *fadump_conf,
 static void __init rtas_fadump_get_config(struct fw_dump *fadump_conf,
 				   const struct rtas_fadump_mem_struct *fdm)
 {
-	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];
+	unsigned long base, size, last_end, hole_size;
 
-	fadump_conf->boot_mem_top = fadump_conf->boot_memory_size;
-	fadump_conf->boot_mem_regs_cnt = 1;
+	last_end = 0;
+	hole_size = 0;
+	fadump_conf->boot_memory_size = 0;
+	fadump_conf->boot_mem_regs_cnt = 0;
+	pr_debug("Boot memory regions:\n");
+	for (int i = 0; i < be16_to_cpu(fdm->header.dump_num_sections); i++) {
+		int type = be16_to_cpu(fdm->rgn[i].source_data_type);
+		u64 addr;
 
-	/*
-	 * Start address of reserve dump area (permanent reservation) for
-	 * re-registering FADump after dump capture.
-	 */
-	fadump_conf->reserve_dump_area_start =
-		be64_to_cpu(fdm->cpu_state_data.destination_address);
+		switch (type) {
+		case RTAS_FADUMP_CPU_STATE_DATA:
+			addr = be64_to_cpu(fdm->rgn[i].destination_address);
+
+			fadump_conf->cpu_state_dest_vaddr = (u64)__va(addr);
+			/*
+			 * Start address of reserve dump area (permanent reservation) for
+			 * re-registering FADump after dump capture.
+			 */
+			fadump_conf->reserve_dump_area_start = addr;
+			break;
+		case RTAS_FADUMP_HPTE_REGION:
+			/* Not processed currently. */
+			break;
+		case RTAS_FADUMP_REAL_MODE_REGION:
+			base = be64_to_cpu(fdm->rgn[i].source_address);
+			size = be64_to_cpu(fdm->rgn[i].source_len);
+			pr_debug("\t[%03d] base: 0x%lx, size: 0x%lx\n", i, base, size);
+			if (!base) {
+				fadump_conf->boot_mem_dest_addr =
+					be64_to_cpu(fdm->rgn[i].destination_address);
+			}
+
+			fadump_conf->boot_mem_addr[fadump_conf->boot_mem_regs_cnt] = base;
+			fadump_conf->boot_mem_sz[fadump_conf->boot_mem_regs_cnt] = size;
+			fadump_conf->boot_memory_size += size;
+			hole_size += (base - last_end);
+			last_end = base + size;
+			fadump_conf->boot_mem_regs_cnt++;
+			break;
+		default:
+			pr_warn("Section type %d unsupported on this kernel. Ignoring!\n", type);
+			break;
+		}
+	}
+	fadump_conf->boot_mem_top = fadump_conf->boot_memory_size + hole_size;
 
 	rtas_fadump_update_config(fadump_conf, fdm);
 }
@@ -64,16 +94,15 @@ static void __init rtas_fadump_get_config(struct fw_dump *fadump_conf,
 static u64 rtas_fadump_init_mem_struct(struct fw_dump *fadump_conf)
 {
 	u64 addr = fadump_conf->reserve_dump_area_start;
+	u16 sec_cnt = 0;
 
 	memset(&fdm, 0, sizeof(struct rtas_fadump_mem_struct));
 	addr = addr & PAGE_MASK;
 
 	fdm.header.dump_format_version = cpu_to_be32(0x00000001);
-	fdm.header.dump_num_sections = cpu_to_be16(3);
 	fdm.header.dump_status_flag = 0;
 	fdm.header.offset_first_dump_section =
-		cpu_to_be32((u32)offsetof(struct rtas_fadump_mem_struct,
-					  cpu_state_data));
+		cpu_to_be32((u32)offsetof(struct rtas_fadump_mem_struct, rgn));
 
 	/*
 	 * Fields for disk dump option.
@@ -89,25 +118,22 @@ static u64 rtas_fadump_init_mem_struct(struct fw_dump *fadump_conf)
 
 	/* Kernel dump sections */
 	/* cpu state data section. */
-	fdm.cpu_state_data.request_flag =
-		cpu_to_be32(RTAS_FADUMP_REQUEST_FLAG);
-	fdm.cpu_state_data.source_data_type =
-		cpu_to_be16(RTAS_FADUMP_CPU_STATE_DATA);
-	fdm.cpu_state_data.source_address = 0;
-	fdm.cpu_state_data.source_len =
-		cpu_to_be64(fadump_conf->cpu_state_data_size);
-	fdm.cpu_state_data.destination_address = cpu_to_be64(addr);
+	fdm.rgn[sec_cnt].request_flag = cpu_to_be32(RTAS_FADUMP_REQUEST_FLAG);
+	fdm.rgn[sec_cnt].source_data_type = cpu_to_be16(RTAS_FADUMP_CPU_STATE_DATA);
+	fdm.rgn[sec_cnt].source_address = 0;
+	fdm.rgn[sec_cnt].source_len = cpu_to_be64(fadump_conf->cpu_state_data_size);
+	fdm.rgn[sec_cnt].destination_address = cpu_to_be64(addr);
 	addr += fadump_conf->cpu_state_data_size;
+	sec_cnt++;
 
 	/* hpte region section */
-	fdm.hpte_region.request_flag = cpu_to_be32(RTAS_FADUMP_REQUEST_FLAG);
-	fdm.hpte_region.source_data_type =
-		cpu_to_be16(RTAS_FADUMP_HPTE_REGION);
-	fdm.hpte_region.source_address = 0;
-	fdm.hpte_region.source_len =
-		cpu_to_be64(fadump_conf->hpte_region_size);
-	fdm.hpte_region.destination_address = cpu_to_be64(addr);
+	fdm.rgn[sec_cnt].request_flag = cpu_to_be32(RTAS_FADUMP_REQUEST_FLAG);
+	fdm.rgn[sec_cnt].source_data_type = cpu_to_be16(RTAS_FADUMP_HPTE_REGION);
+	fdm.rgn[sec_cnt].source_address = 0;
+	fdm.rgn[sec_cnt].source_len = cpu_to_be64(fadump_conf->hpte_region_size);
+	fdm.rgn[sec_cnt].destination_address = cpu_to_be64(addr);
 	addr += fadump_conf->hpte_region_size;
+	sec_cnt++;
 
 	/*
 	 * Align boot memory area destination address to page boundary to
@@ -115,15 +141,20 @@ static u64 rtas_fadump_init_mem_struct(struct fw_dump *fadump_conf)
 	 */
 	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 =
-		cpu_to_be16(RTAS_FADUMP_REAL_MODE_REGION);
-	fdm.rmr_region.source_address = cpu_to_be64(0);
-	fdm.rmr_region.source_len = cpu_to_be64(fadump_conf->boot_memory_size);
-	fdm.rmr_region.destination_address = cpu_to_be64(addr);
-	addr += fadump_conf->boot_memory_size;
+	/* First boot memory region destination address */
+	fadump_conf->boot_mem_dest_addr = addr;
+	for (int i = 0; i < fadump_conf->boot_mem_regs_cnt; i++) {
+		/* Boot memory regions */
+		fdm.rgn[sec_cnt].request_flag = cpu_to_be32(RTAS_FADUMP_REQUEST_FLAG);
+		fdm.rgn[sec_cnt].source_data_type = cpu_to_be16(RTAS_FADUMP_REAL_MODE_REGION);
+		fdm.rgn[sec_cnt].source_address = cpu_to_be64(fadump_conf->boot_mem_addr[i]);
+		fdm.rgn[sec_cnt].source_len = cpu_to_be64(fadump_conf->boot_mem_sz[i]);
+		fdm.rgn[sec_cnt].destination_address = cpu_to_be64(addr);
+		addr += fadump_conf->boot_mem_sz[i];
+		sec_cnt++;
+	}
 
+	fdm.header.dump_num_sections = cpu_to_be16(sec_cnt);
 	rtas_fadump_update_config(fadump_conf, &fdm);
 
 	return addr;
@@ -136,14 +167,21 @@ static u64 rtas_fadump_get_bootmem_min(void)
 
 static int rtas_fadump_register(struct fw_dump *fadump_conf)
 {
-	unsigned int wait_time;
+	unsigned int wait_time, fdm_size;
 	int rc, err = -EIO;
 
+	/*
+	 * Platform requires the exact size of the Dump Memory Structure.
+	 * Avoid including any unused rgns in the calculation, as this
+	 * could result in a parameter error (-3) from the platform.
+	 */
+	fdm_size = sizeof(struct rtas_fadump_section_header);
+	fdm_size += be16_to_cpu(fdm.header.dump_num_sections) * sizeof(struct rtas_fadump_section);
+
 	/* TODO: Add upper time limit for the delay */
 	do {
 		rc =  rtas_call(fadump_conf->ibm_configure_kernel_dump, 3, 1,
-				NULL, FADUMP_REGISTER, &fdm,
-				sizeof(struct rtas_fadump_mem_struct));
+				NULL, FADUMP_REGISTER, &fdm, fdm_size);
 
 		wait_time = rtas_busy_delay_time(rc);
 		if (wait_time)
@@ -161,9 +199,7 @@ static int rtas_fadump_register(struct fw_dump *fadump_conf)
 		pr_err("Failed to register. Hardware Error(%d).\n", rc);
 		break;
 	case -3:
-		if (!is_fadump_boot_mem_contiguous())
-			pr_err("Can't have holes in boot memory area.\n");
-		else if (!is_fadump_reserved_mem_contiguous())
+		if (!is_fadump_reserved_mem_contiguous())
 			pr_err("Can't have holes in reserved memory area.\n");
 
 		pr_err("Failed to register. Parameter Error(%d).\n", rc);
@@ -316,11 +352,9 @@ static int __init rtas_fadump_build_cpu_notes(struct fw_dump *fadump_conf)
 	u32 num_cpus, *note_buf;
 	int i, rc = 0, cpu = 0;
 	struct pt_regs regs;
-	unsigned long addr;
 	void *vaddr;
 
-	addr = be64_to_cpu(fdm_active->cpu_state_data.destination_address);
-	vaddr = __va(addr);
+	vaddr = (void *)fadump_conf->cpu_state_dest_vaddr;
 
 	reg_header = vaddr;
 	if (be64_to_cpu(reg_header->magic_number) !=
@@ -395,18 +429,42 @@ static int __init rtas_fadump_process(struct fw_dump *fadump_conf)
 		return -EINVAL;
 
 	/* Check if the dump data is valid. */
-	if ((be16_to_cpu(fdm_active->header.dump_status_flag) ==
-			RTAS_FADUMP_ERROR_FLAG) ||
-			(fdm_active->cpu_state_data.error_flags != 0) ||
-			(fdm_active->rmr_region.error_flags != 0)) {
-		pr_err("Dump taken by platform is not valid\n");
-		return -EINVAL;
-	}
-	if ((fdm_active->rmr_region.bytes_dumped !=
-			fdm_active->rmr_region.source_len) ||
-			!fdm_active->cpu_state_data.bytes_dumped) {
-		pr_err("Dump taken by platform is incomplete\n");
-		return -EINVAL;
+	for (int i = 0; i < be16_to_cpu(fdm_active->header.dump_num_sections); i++) {
+		int type = be16_to_cpu(fdm_active->rgn[i].source_data_type);
+		int rc = 0;
+
+		switch (type) {
+		case RTAS_FADUMP_CPU_STATE_DATA:
+		case RTAS_FADUMP_HPTE_REGION:
+		case RTAS_FADUMP_REAL_MODE_REGION:
+			if (fdm_active->rgn[i].error_flags != 0) {
+				pr_err("Dump taken by platform is not valid (%d)\n", i);
+				rc = -EINVAL;
+			}
+			if (fdm_active->rgn[i].bytes_dumped != fdm_active->rgn[i].source_len) {
+				pr_err("Dump taken by platform is incomplete (%d)\n", i);
+				rc = -EINVAL;
+			}
+			if (rc) {
+				pr_warn("Region type: %u src addr: 0x%llx dest addr: 0x%llx\n",
+					be16_to_cpu(fdm_active->rgn[i].source_data_type),
+					be64_to_cpu(fdm_active->rgn[i].source_address),
+					be64_to_cpu(fdm_active->rgn[i].destination_address));
+				return rc;
+			}
+			break;
+		default:
+			/*
+			 * If the first/crashed kernel added a new region type that the
+			 * second/fadump kernel doesn't recognize, skip it and process
+			 * assuming backward compatibility.
+			 */
+			pr_warn("Unknown region found: type: %u src addr: 0x%llx dest addr: 0x%llx\n",
+				be16_to_cpu(fdm_active->rgn[i].source_data_type),
+				be64_to_cpu(fdm_active->rgn[i].source_address),
+				be64_to_cpu(fdm_active->rgn[i].destination_address));
+			break;
+		}
 	}
 
 	return rtas_fadump_build_cpu_notes(fadump_conf);
@@ -415,7 +473,6 @@ static int __init rtas_fadump_process(struct fw_dump *fadump_conf)
 static void rtas_fadump_region_show(struct fw_dump *fadump_conf,
 				    struct seq_file *m)
 {
-	const struct rtas_fadump_section *cpu_data_section;
 	const struct rtas_fadump_mem_struct *fdm_ptr;
 
 	if (fdm_active)
@@ -423,27 +480,42 @@ static void rtas_fadump_region_show(struct fw_dump *fadump_conf,
 	else
 		fdm_ptr = &fdm;
 
-	cpu_data_section = &(fdm_ptr->cpu_state_data);
-	seq_printf(m, "CPU :[%#016llx-%#016llx] %#llx bytes, Dumped: %#llx\n",
-		   be64_to_cpu(cpu_data_section->destination_address),
-		   be64_to_cpu(cpu_data_section->destination_address) +
-		   be64_to_cpu(cpu_data_section->source_len) - 1,
-		   be64_to_cpu(cpu_data_section->source_len),
-		   be64_to_cpu(cpu_data_section->bytes_dumped));
-
-	seq_printf(m, "HPTE:[%#016llx-%#016llx] %#llx bytes, Dumped: %#llx\n",
-		   be64_to_cpu(fdm_ptr->hpte_region.destination_address),
-		   be64_to_cpu(fdm_ptr->hpte_region.destination_address) +
-		   be64_to_cpu(fdm_ptr->hpte_region.source_len) - 1,
-		   be64_to_cpu(fdm_ptr->hpte_region.source_len),
-		   be64_to_cpu(fdm_ptr->hpte_region.bytes_dumped));
-
-	seq_printf(m, "DUMP: Src: %#016llx, Dest: %#016llx, ",
-		   be64_to_cpu(fdm_ptr->rmr_region.source_address),
-		   be64_to_cpu(fdm_ptr->rmr_region.destination_address));
-	seq_printf(m, "Size: %#llx, Dumped: %#llx bytes\n",
-		   be64_to_cpu(fdm_ptr->rmr_region.source_len),
-		   be64_to_cpu(fdm_ptr->rmr_region.bytes_dumped));
+
+	for (int i = 0; i < be16_to_cpu(fdm_ptr->header.dump_num_sections); i++) {
+		int type = be16_to_cpu(fdm_ptr->rgn[i].source_data_type);
+
+		switch (type) {
+		case RTAS_FADUMP_CPU_STATE_DATA:
+			seq_printf(m, "CPU :[%#016llx-%#016llx] %#llx bytes, Dumped: %#llx\n",
+				   be64_to_cpu(fdm_ptr->rgn[i].destination_address),
+				   be64_to_cpu(fdm_ptr->rgn[i].destination_address) +
+				   be64_to_cpu(fdm_ptr->rgn[i].source_len) - 1,
+				   be64_to_cpu(fdm_ptr->rgn[i].source_len),
+				   be64_to_cpu(fdm_ptr->rgn[i].bytes_dumped));
+			break;
+		case RTAS_FADUMP_HPTE_REGION:
+			seq_printf(m, "HPTE:[%#016llx-%#016llx] %#llx bytes, Dumped: %#llx\n",
+				   be64_to_cpu(fdm_ptr->rgn[i].destination_address),
+				   be64_to_cpu(fdm_ptr->rgn[i].destination_address) +
+				   be64_to_cpu(fdm_ptr->rgn[i].source_len) - 1,
+				   be64_to_cpu(fdm_ptr->rgn[i].source_len),
+				   be64_to_cpu(fdm_ptr->rgn[i].bytes_dumped));
+			break;
+		case RTAS_FADUMP_REAL_MODE_REGION:
+			seq_printf(m, "DUMP: Src: %#016llx, Dest: %#016llx, ",
+				   be64_to_cpu(fdm_ptr->rgn[i].source_address),
+				   be64_to_cpu(fdm_ptr->rgn[i].destination_address));
+			seq_printf(m, "Size: %#llx, Dumped: %#llx bytes\n",
+				   be64_to_cpu(fdm_ptr->rgn[i].source_len),
+				   be64_to_cpu(fdm_ptr->rgn[i].bytes_dumped));
+			break;
+		default:
+			seq_printf(m, "Unknown region type %d : Src: %#016llx, Dest: %#016llx, ",
+				   type, be64_to_cpu(fdm_ptr->rgn[i].source_address),
+				   be64_to_cpu(fdm_ptr->rgn[i].destination_address));
+			break;
+		}
+	}
 
 	/* Dump is active. Show preserved area start address. */
 	if (fdm_active) {
@@ -459,6 +531,20 @@ static void rtas_fadump_trigger(struct fadump_crash_info_header *fdh,
 	rtas_os_term((char *)msg);
 }
 
+/* FADUMP_MAX_MEM_REGS or lower */
+static int rtas_fadump_max_boot_mem_rgns(void)
+{
+	/*
+	 * Version 1 of Kernel Assisted Dump Memory Structure (PAPR) supports 10 sections.
+	 * With one each section taken for CPU state data & HPTE respectively, 8 sections
+	 * can be used for boot memory regions.
+	 *
+	 * If new region(s) is(are) defined, maximum boot memory regions will decrease
+	 * proportionally.
+	 */
+	return RTAS_FADUMP_MAX_BOOT_MEM_REGS;
+}
+
 static struct fadump_ops rtas_fadump_ops = {
 	.fadump_init_mem_struct		= rtas_fadump_init_mem_struct,
 	.fadump_get_bootmem_min		= rtas_fadump_get_bootmem_min,
@@ -468,6 +554,7 @@ static struct fadump_ops rtas_fadump_ops = {
 	.fadump_process			= rtas_fadump_process,
 	.fadump_region_show		= rtas_fadump_region_show,
 	.fadump_trigger			= rtas_fadump_trigger,
+	.fadump_max_boot_mem_rgns	= rtas_fadump_max_boot_mem_rgns,
 };
 
 void __init rtas_fadump_dt_scan(struct fw_dump *fadump_conf, u64 node)
diff --git a/arch/powerpc/platforms/pseries/rtas-fadump.h b/arch/powerpc/platforms/pseries/rtas-fadump.h
index fd59bd7ca9c3..6740f4981bb8 100644
--- a/arch/powerpc/platforms/pseries/rtas-fadump.h
+++ b/arch/powerpc/platforms/pseries/rtas-fadump.h
@@ -29,6 +29,15 @@
 /* Dump status flag */
 #define RTAS_FADUMP_ERROR_FLAG		0x2000
 
+/*
+ * The Firmware Assisted Dump Memory structure supports a maximum of 10 sections
+ * in the dump memory structure. Presently, first two sections are used for
+ * CPU and HPTE data, while the remaining eight sections can be used for
+ * boot memory regions.
+ */
+#define MAX_SECTIONS				10
+#define RTAS_FADUMP_MAX_BOOT_MEM_REGS		8
+
 /* Kernel Dump section info */
 struct rtas_fadump_section {
 	__be32	request_flag;
@@ -61,20 +70,15 @@ struct rtas_fadump_section_header {
  * Firmware Assisted dump memory structure. This structure is required for
  * registering future kernel dump with power firmware through rtas call.
  *
- * No disk dump option. Hence disk dump path string section is not included.
+ * In version 1, the platform permits one section header, dump-disk path
+ * and ten sections.
+ *
+ * Note: No disk dump option. Hence disk dump path string section is not
+ * included.
  */
 struct rtas_fadump_mem_struct {
 	struct rtas_fadump_section_header	header;
-
-	/* 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;
+	struct rtas_fadump_section		rgn[MAX_SECTIONS];
 };
 
 /*
-- 
2.45.0

[PATCH v2 2/3] powerpc/fadump: setup additional parameters for dump capture kernel

[Hari Bathini]

For fadump case, passing additional parameters to dump capture kernel
helps in minimizing the memory footprint for it and also provides the
flexibility to disable components/modules, like hugepages, that are
hindering the boot process of the special dump capture environment.

Set up a dedicated parameter area to be passed to the capture kernel.
This area type is defined as RTAS_FADUMP_PARAM_AREA. Sysfs attribute
'/sys/kernel/fadump/bootargs_append' is exported to the userspace to
specify the additional parameters to be passed to the capture kernel

Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
---
 arch/powerpc/include/asm/fadump-internal.h   |  3 +
 arch/powerpc/kernel/fadump.c                 | 87 ++++++++++++++++++++
 arch/powerpc/platforms/powernv/opal-fadump.c |  6 +-
 arch/powerpc/platforms/pseries/rtas-fadump.c | 35 +++++++-
 arch/powerpc/platforms/pseries/rtas-fadump.h | 11 ++-
 5 files changed, 133 insertions(+), 9 deletions(-)

diff --git a/arch/powerpc/include/asm/fadump-internal.h b/arch/powerpc/include/asm/fadump-internal.h
index 35787fa1ac60..e83869a4eb6a 100644
--- a/arch/powerpc/include/asm/fadump-internal.h
+++ b/arch/powerpc/include/asm/fadump-internal.h
@@ -124,6 +124,8 @@ struct fw_dump {
 	unsigned long	cpu_notes_buf_vaddr;
 	unsigned long	cpu_notes_buf_size;
 
+	unsigned long	param_area;
+
 	/*
 	 * Maximum size supported by firmware to copy from source to
 	 * destination address per entry.
@@ -138,6 +140,7 @@ struct fw_dump {
 	unsigned long	dump_active:1;
 	unsigned long	dump_registered:1;
 	unsigned long	nocma:1;
+	unsigned long	param_area_supported:1;
 
 	struct fadump_ops	*ops;
 };
diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
index fe6be00451b9..6d35b09d6f3a 100644
--- a/arch/powerpc/kernel/fadump.c
+++ b/arch/powerpc/kernel/fadump.c
@@ -1431,6 +1431,43 @@ static ssize_t registered_show(struct kobject *kobj,
 	return sprintf(buf, "%d\n", fw_dump.dump_registered);
 }
 
+static ssize_t bootargs_append_show(struct kobject *kobj,
+				   struct kobj_attribute *attr,
+				   char *buf)
+{
+	return sprintf(buf, "%s\n", (char *)__va(fw_dump.param_area));
+}
+
+static ssize_t bootargs_append_store(struct kobject *kobj,
+				   struct kobj_attribute *attr,
+				   const char *buf, size_t count)
+{
+	char *params;
+
+	if (!fw_dump.fadump_enabled || fw_dump.dump_active)
+		return -EPERM;
+
+	if (count >= COMMAND_LINE_SIZE)
+		return -EINVAL;
+
+	/*
+	 * Fail here instead of handling this scenario with
+	 * some silly workaround in capture kernel.
+	 */
+	if (saved_command_line_len + count >= COMMAND_LINE_SIZE) {
+		pr_err("Appending parameters exceeds cmdline size!\n");
+		return -ENOSPC;
+	}
+
+	params = __va(fw_dump.param_area);
+	strscpy_pad(params, buf, COMMAND_LINE_SIZE);
+	/* Remove newline character at the end. */
+	if (params[count-1] == '\n')
+		params[count-1] = '\0';
+
+	return count;
+}
+
 static ssize_t registered_store(struct kobject *kobj,
 				struct kobj_attribute *attr,
 				const char *buf, size_t count)
@@ -1490,6 +1527,7 @@ static struct kobj_attribute enable_attr = __ATTR_RO(enabled);
 static struct kobj_attribute register_attr = __ATTR_RW(registered);
 static struct kobj_attribute mem_reserved_attr = __ATTR_RO(mem_reserved);
 static struct kobj_attribute hotplug_ready_attr = __ATTR_RO(hotplug_ready);
+static struct kobj_attribute bootargs_append_attr = __ATTR_RW(bootargs_append);
 
 static struct attribute *fadump_attrs[] = {
 	&enable_attr.attr,
@@ -1663,6 +1701,54 @@ static void __init fadump_process(void)
 	fadump_invalidate_release_mem();
 }
 
+/*
+ * Reserve memory to store additional parameters to be passed
+ * for fadump/capture kernel.
+ */
+static void fadump_setup_param_area(void)
+{
+	phys_addr_t range_start, range_end;
+
+	if (!fw_dump.param_area_supported || fw_dump.dump_active)
+		return;
+
+	/* This memory can't be used by PFW or bootloader as it is shared across kernels */
+	if (radix_enabled()) {
+		/*
+		 * Anywhere in the upper half should be good enough as all memory
+		 * is accessible in real mode.
+		 */
+		range_start = memblock_end_of_DRAM() / 2;
+		range_end = memblock_end_of_DRAM();
+	} else {
+		/*
+		 * Passing additional parameters is supported for hash MMU only
+		 * if the first memory block size is 768MB or higher.
+		 */
+		if (ppc64_rma_size < 0x30000000)
+			return;
+
+		/*
+		 * 640 MB to 768 MB is not used by PFW/bootloader. So, try reserving
+		 * memory for passing additional parameters in this range to avoid
+		 * being stomped on by PFW/bootloader.
+		 */
+		range_start = 0x2A000000;
+		range_end = range_start + 0x4000000;
+	}
+
+	fw_dump.param_area = memblock_phys_alloc_range(COMMAND_LINE_SIZE,
+						       COMMAND_LINE_SIZE,
+						       range_start,
+						       range_end);
+	if (!fw_dump.param_area || sysfs_create_file(fadump_kobj, &bootargs_append_attr.attr)) {
+		pr_warn("WARNING: Could not setup area to pass additional parameters!\n");
+		return;
+	}
+
+	memset(phys_to_virt(fw_dump.param_area), 0, COMMAND_LINE_SIZE);
+}
+
 /*
  * Prepare for firmware-assisted dump.
  */
@@ -1686,6 +1772,7 @@ int __init setup_fadump(void)
 	}
 	/* Initialize the kernel dump memory structure and register with f/w */
 	else if (fw_dump.reserve_dump_area_size) {
+		fadump_setup_param_area();
 		fw_dump.ops->fadump_init_mem_struct(&fw_dump);
 		register_fadump();
 	}
diff --git a/arch/powerpc/platforms/powernv/opal-fadump.c b/arch/powerpc/platforms/powernv/opal-fadump.c
index 5a88d7efb48a..c9c1dfb35464 100644
--- a/arch/powerpc/platforms/powernv/opal-fadump.c
+++ b/arch/powerpc/platforms/powernv/opal-fadump.c
@@ -665,8 +665,10 @@ void __init opal_fadump_dt_scan(struct fw_dump *fadump_conf, u64 node)
 		}
 	}
 
-	fadump_conf->ops		= &opal_fadump_ops;
-	fadump_conf->fadump_supported	= 1;
+	fadump_conf->ops			= &opal_fadump_ops;
+	fadump_conf->fadump_supported		= 1;
+	/* TODO: Add support to pass additional parameters */
+	fadump_conf->param_area_supported	= 0;
 
 	/*
 	 * Firmware supports 32-bit field for size. Align it to PAGE_SIZE
diff --git a/arch/powerpc/platforms/pseries/rtas-fadump.c b/arch/powerpc/platforms/pseries/rtas-fadump.c
index 4db78b2bb2a8..eceb3289383e 100644
--- a/arch/powerpc/platforms/pseries/rtas-fadump.c
+++ b/arch/powerpc/platforms/pseries/rtas-fadump.c
@@ -18,6 +18,7 @@
 
 #include <asm/page.h>
 #include <asm/rtas.h>
+#include <asm/setup.h>
 #include <asm/fadump.h>
 #include <asm/fadump-internal.h>
 
@@ -81,6 +82,9 @@ static void __init rtas_fadump_get_config(struct fw_dump *fadump_conf,
 			last_end = base + size;
 			fadump_conf->boot_mem_regs_cnt++;
 			break;
+		case RTAS_FADUMP_PARAM_AREA:
+			fadump_conf->param_area = be64_to_cpu(fdm->rgn[i].destination_address);
+			break;
 		default:
 			pr_warn("Section type %d unsupported on this kernel. Ignoring!\n", type);
 			break;
@@ -154,7 +158,17 @@ static u64 rtas_fadump_init_mem_struct(struct fw_dump *fadump_conf)
 		sec_cnt++;
 	}
 
+	/* Parameters area */
+	if (fadump_conf->param_area) {
+		fdm.rgn[sec_cnt].request_flag = cpu_to_be32(RTAS_FADUMP_REQUEST_FLAG);
+		fdm.rgn[sec_cnt].source_data_type = cpu_to_be16(RTAS_FADUMP_PARAM_AREA);
+		fdm.rgn[sec_cnt].source_address = cpu_to_be64(fadump_conf->param_area);
+		fdm.rgn[sec_cnt].source_len = cpu_to_be64(COMMAND_LINE_SIZE);
+		fdm.rgn[sec_cnt].destination_address = cpu_to_be64(fadump_conf->param_area);
+		sec_cnt++;
+	}
 	fdm.header.dump_num_sections = cpu_to_be16(sec_cnt);
+
 	rtas_fadump_update_config(fadump_conf, &fdm);
 
 	return addr;
@@ -453,6 +467,13 @@ static int __init rtas_fadump_process(struct fw_dump *fadump_conf)
 				return rc;
 			}
 			break;
+		case RTAS_FADUMP_PARAM_AREA:
+			if (fdm_active->rgn[i].bytes_dumped != fdm_active->rgn[i].source_len ||
+			    fdm_active->rgn[i].error_flags != 0) {
+				pr_warn("Failed to process additional parameters! Proceeding anyway..\n");
+				fadump_conf->param_area = 0;
+			}
+			break;
 		default:
 			/*
 			 * If the first/crashed kernel added a new region type that the
@@ -509,6 +530,13 @@ static void rtas_fadump_region_show(struct fw_dump *fadump_conf,
 				   be64_to_cpu(fdm_ptr->rgn[i].source_len),
 				   be64_to_cpu(fdm_ptr->rgn[i].bytes_dumped));
 			break;
+		case RTAS_FADUMP_PARAM_AREA:
+			seq_printf(m, "\n[%#016llx-%#016llx]: cmdline append: '%s'\n",
+				   be64_to_cpu(fdm_ptr->rgn[i].destination_address),
+				   be64_to_cpu(fdm_ptr->rgn[i].destination_address) +
+				   be64_to_cpu(fdm_ptr->rgn[i].source_len) - 1,
+				   (char *)__va(be64_to_cpu(fdm_ptr->rgn[i].destination_address)));
+			break;
 		default:
 			seq_printf(m, "Unknown region type %d : Src: %#016llx, Dest: %#016llx, ",
 				   type, be64_to_cpu(fdm_ptr->rgn[i].source_address),
@@ -571,9 +599,10 @@ void __init rtas_fadump_dt_scan(struct fw_dump *fadump_conf, u64 node)
 	if (!token)
 		return;
 
-	fadump_conf->ibm_configure_kernel_dump = be32_to_cpu(*token);
-	fadump_conf->ops		= &rtas_fadump_ops;
-	fadump_conf->fadump_supported	= 1;
+	fadump_conf->ibm_configure_kernel_dump	= be32_to_cpu(*token);
+	fadump_conf->ops			= &rtas_fadump_ops;
+	fadump_conf->fadump_supported		= 1;
+	fadump_conf->param_area_supported	= 1;
 
 	/* Firmware supports 64-bit value for size, align it to pagesize. */
 	fadump_conf->max_copy_size = ALIGN_DOWN(U64_MAX, PAGE_SIZE);
diff --git a/arch/powerpc/platforms/pseries/rtas-fadump.h b/arch/powerpc/platforms/pseries/rtas-fadump.h
index 6740f4981bb8..c109abf6befd 100644
--- a/arch/powerpc/platforms/pseries/rtas-fadump.h
+++ b/arch/powerpc/platforms/pseries/rtas-fadump.h
@@ -23,6 +23,9 @@
 #define RTAS_FADUMP_HPTE_REGION		0x0002
 #define RTAS_FADUMP_REAL_MODE_REGION	0x0011
 
+/* OS defined sections */
+#define RTAS_FADUMP_PARAM_AREA		0x0100
+
 /* Dump request flag */
 #define RTAS_FADUMP_REQUEST_FLAG	0x00000001
 
@@ -31,12 +34,12 @@
 
 /*
  * The Firmware Assisted Dump Memory structure supports a maximum of 10 sections
- * in the dump memory structure. Presently, first two sections are used for
- * CPU and HPTE data, while the remaining eight sections can be used for
- * boot memory regions.
+ * in the dump memory structure. Presently, three sections are used for
+ * CPU state data, HPTE & Parameters area, while the remaining seven sections
+ * can be used for boot memory regions.
  */
 #define MAX_SECTIONS				10
-#define RTAS_FADUMP_MAX_BOOT_MEM_REGS		8
+#define RTAS_FADUMP_MAX_BOOT_MEM_REGS		7
 
 /* Kernel Dump section info */
 struct rtas_fadump_section {
-- 
2.45.0

[PATCH v2 3/3] powerpc/fadump: pass additional parameters when fadump is active

[Hari Bathini]

Append the additional parameters passed/set in the dedicated parameter
area (RTAS_FADUMP_PARAM_AREA) to bootargs in fadump capture kernel.

Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
---
 arch/powerpc/include/asm/fadump.h |  2 ++
 arch/powerpc/kernel/fadump.c      | 35 +++++++++++++++++++++++++++++++
 arch/powerpc/kernel/prom.c        |  3 +++
 3 files changed, 40 insertions(+)

diff --git a/arch/powerpc/include/asm/fadump.h b/arch/powerpc/include/asm/fadump.h
index 526a6a647312..ef40c9b6972a 100644
--- a/arch/powerpc/include/asm/fadump.h
+++ b/arch/powerpc/include/asm/fadump.h
@@ -19,12 +19,14 @@ extern int is_fadump_active(void);
 extern int should_fadump_crash(void);
 extern void crash_fadump(struct pt_regs *, const char *);
 extern void fadump_cleanup(void);
+extern void fadump_append_bootargs(void);
 
 #else	/* CONFIG_FA_DUMP */
 static inline int is_fadump_active(void) { return 0; }
 static inline int should_fadump_crash(void) { return 0; }
 static inline void crash_fadump(struct pt_regs *regs, const char *str) { }
 static inline void fadump_cleanup(void) { }
+static inline void fadump_append_bootargs(void) { }
 #endif /* !CONFIG_FA_DUMP */
 
 #if defined(CONFIG_FA_DUMP) || defined(CONFIG_PRESERVE_FA_DUMP)
diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
index 6d35b09d6f3a..2276bacc4170 100644
--- a/arch/powerpc/kernel/fadump.c
+++ b/arch/powerpc/kernel/fadump.c
@@ -131,6 +131,41 @@ static int __init fadump_cma_init(void)
 static int __init fadump_cma_init(void) { return 1; }
 #endif /* CONFIG_CMA */
 
+/*
+ * Additional parameters meant for capture kernel are placed in a dedicated area.
+ * If this is capture kernel boot, append these parameters to bootargs.
+ */
+void __init fadump_append_bootargs(void)
+{
+	char *append_args;
+	size_t len;
+
+	if (!fw_dump.dump_active || !fw_dump.param_area_supported || !fw_dump.param_area)
+		return;
+
+	if (fw_dump.param_area >= fw_dump.boot_mem_top) {
+		if (memblock_reserve(fw_dump.param_area, COMMAND_LINE_SIZE)) {
+			pr_warn("WARNING: Can't use additional parameters area!\n");
+			fw_dump.param_area = 0;
+			return;
+		}
+	}
+
+	append_args = (char *)fw_dump.param_area;
+	len = strlen(boot_command_line);
+
+	/*
+	 * Too late to fail even if cmdline size exceeds. Truncate additional parameters
+	 * to cmdline size and proceed anyway.
+	 */
+	if (len + strlen(append_args) >= COMMAND_LINE_SIZE - 1)
+		pr_warn("WARNING: Appending parameters exceeds cmdline size. Truncating!\n");
+
+	pr_debug("Cmdline: %s\n", boot_command_line);
+	snprintf(boot_command_line + len, COMMAND_LINE_SIZE - len, " %s", append_args);
+	pr_info("Updated cmdline: %s\n", boot_command_line);
+}
+
 /* Scan the Firmware Assisted dump configuration details. */
 int __init early_init_dt_scan_fw_dump(unsigned long node, const char *uname,
 				      int depth, void *data)
diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
index eb140ea6b6ff..60819751e55e 100644
--- a/arch/powerpc/kernel/prom.c
+++ b/arch/powerpc/kernel/prom.c
@@ -813,6 +813,9 @@ void __init early_init_devtree(void *params)
 	 */
 	of_scan_flat_dt(early_init_dt_scan_chosen_ppc, boot_command_line);
 
+	/* Append additional parameters passed for fadump capture kernel */
+	fadump_append_bootargs();
+
 	/* Scan memory nodes and rebuild MEMBLOCKs */
 	early_init_dt_scan_root();
 	early_init_dt_scan_memory_ppc();
-- 
2.45.0

Re: [PATCH v2 0/3] powerpc/fadump: pass additional args to dump capture kernel

[Michael Ellerman]

On Thu, 09 May 2024 17:27:52 +0530, Hari Bathini wrote:
> While fadump is a more reliable alternative to kdump dump capturing
> method, it doesn't support passing additional parameters. Having
> such support is desirable for two major reasons:
> 
>   1. It helps minimize the memory consumption of fadump dump capture
>      kernel by disabling features that consume considerable amount of
>      memory but have little significance for dump capture environment
>      (eg. numa, cma, cgroup, etc.)
>    2. It helps disable such features/components in dump capture kernel
>       that are unstable and/or are being debugged.
> 
> [...]

Applied to powerpc/next.

[1/3] powerpc/pseries/fadump: add support for multiple boot memory regions
      https://git.kernel.org/powerpc/c/78d5cc15fb7d1b2683f0baf418a9a870c02319fb
[2/3] powerpc/fadump: setup additional parameters for dump capture kernel
      https://git.kernel.org/powerpc/c/683eab94da75bcf55a9c65e0c31d0529edebe86d
[3/3] powerpc/fadump: pass additional parameters when fadump is active
      https://git.kernel.org/powerpc/c/3416c9daa6b13c0e2a656d4e2dee8de95f9a38cf

cheers