Subject: [PATCH 5/8] pseries: phyp dump: register dump area.

From: Manish Ahuja <[email-masked]>
Date: Mon, 07 Jan 2008 18:28:30 -0600

Set up the actual dump header, register it with the hypervisor.

Signed-off-by: Manish Ahuja <[email-masked]>
Signed-off-by: Linas Vepstas <[email-masked]>

------
 arch/powerpc/platforms/pseries/phyp_dump.c |  169 +++++++++++++++++++++++++++--
 1 file changed, 163 insertions(+), 6 deletions(-)

Index: linux-2.6.24-rc3-git1/arch/powerpc/platforms/pseries/phyp_dump.c
===================================================================
--- linux-2.6.24-rc3-git1.orig/arch/powerpc/platforms/pseries/phyp_dump.c	2007-11-21 15:55:37.000000000 -0600
+++ linux-2.6.24-rc3-git1/arch/powerpc/platforms/pseries/phyp_dump.c	2007-11-21 16:06:52.000000000 -0600
@@ -30,6 +30,134 @@ struct phyp_dump *phyp_dump_info = &phyp
 static int ibm_configure_kernel_dump;
 
 /* ------------------------------------------------- */
+/* RTAS interfaces to declare the dump regions */
+
+struct dump_section {
+	u32 dump_flags;
+	u16 source_type;
+	u16 error_flags;
+	u64 source_address;
+	u64 source_length;
+	u64 length_copied;
+	u64 destination_address;
+};
+
+struct phyp_dump_header {
+	u32 version;
+	u16 num_of_sections;
+	u16 status;
+
+	u32 first_offset_section;
+	u32 dump_disk_section;
+	u64 block_num_dd;
+	u64 num_of_blocks_dd;
+	u32 offset_dd;
+	u32 maxtime_to_auto;
+	/* No dump disk path string used */
+
+	struct dump_section cpu_data;
+	struct dump_section hpte_data;
+	struct dump_section kernel_data;
+};
+
+/* The dump header *must be* in low memory, so .bss it */
+static struct phyp_dump_header phdr;
+
+#define NUM_DUMP_SECTIONS 3
+#define DUMP_HEADER_VERSION 0x1
+#define DUMP_REQUEST_FLAG 0x1
+#define DUMP_SOURCE_CPU 0x0001
+#define DUMP_SOURCE_HPTE 0x0002
+#define DUMP_SOURCE_RMO  0x0011
+
+/**
+ * init_dump_header() - initialize the header declaring a dump
+ * Returns: length of dump save area.
+ *
+ * When the hypervisor saves crashed state, it needs to put
+ * it somewhere. The dump header tells the hypervisor where
+ * the data can be saved.
+ */
+static unsigned long init_dump_header(struct phyp_dump_header *ph)
+{
+	struct device_node *rtas;
+	const unsigned int *sizes;
+	int len;
+	unsigned long cpu_state_size = 0;
+	unsigned long hpte_region_size = 0;
+	unsigned long addr_offset = 0;
+
+	/* Get the required dump region sizes */
+	rtas = of_find_node_by_path("/rtas");
+	sizes = of_get_property(rtas, "ibm,configure-kernel-dump-sizes", &len);
+	if (!sizes || len < 20)
+		return 0;
+
+	if (sizes[0] == 1)
+		cpu_state_size = *((unsigned long *) &sizes[1]);
+
+	if (sizes[3] == 2)
+		hpte_region_size = *((unsigned long *) &sizes[4]);
+
+	/* Set up the dump header */
+	ph->version = DUMP_HEADER_VERSION;
+	ph->num_of_sections = NUM_DUMP_SECTIONS;
+	ph->status = 0;
+
+	ph->first_offset_section =
+		(u32) &(((struct phyp_dump_header *) 0)->cpu_data);
+	ph->dump_disk_section = 0;
+	ph->block_num_dd = 0;
+	ph->num_of_blocks_dd = 0;
+	ph->offset_dd = 0;
+
+	ph->maxtime_to_auto = 0; /* disabled */
+
+	/* The first two sections are mandatory */
+	ph->cpu_data.dump_flags = DUMP_REQUEST_FLAG;
+	ph->cpu_data.source_type = DUMP_SOURCE_CPU;
+	ph->cpu_data.source_address = 0;
+	ph->cpu_data.source_length = cpu_state_size;
+	ph->cpu_data.destination_address = addr_offset;
+	addr_offset += cpu_state_size;
+
+	ph->hpte_data.dump_flags = DUMP_REQUEST_FLAG;
+	ph->hpte_data.source_type = DUMP_SOURCE_HPTE;
+	ph->hpte_data.source_address = 0;
+	ph->hpte_data.source_length = hpte_region_size;
+	ph->hpte_data.destination_address = addr_offset;
+	addr_offset += hpte_region_size;
+
+	/* This section describes the low kernel region */
+	ph->kernel_data.dump_flags = DUMP_REQUEST_FLAG;
+	ph->kernel_data.source_type = DUMP_SOURCE_RMO;
+	ph->kernel_data.source_address = PHYP_DUMP_RMR_START;
+	ph->kernel_data.source_length = PHYP_DUMP_RMR_END;
+	ph->kernel_data.destination_address = addr_offset;
+	addr_offset += ph->kernel_data.source_length;
+
+	return addr_offset;
+}
+
+static void register_dump_area(struct phyp_dump_header *ph, unsigned long addr)
+{
+	int rc;
+	ph->cpu_data.destination_address += addr;
+	ph->hpte_data.destination_address += addr;
+	ph->kernel_data.destination_address += addr;
+
+	do {
+		rc = rtas_call(ibm_configure_kernel_dump, 3, 1, NULL,
+		               1, ph, sizeof(struct phyp_dump_header));
+	} while (rtas_busy_delay(rc));
+
+	if (rc)
+	{
+		printk (KERN_ERR "phyp-dump: unexpected error (%d) on register\n", rc);
+	}
+}
+
+/* ------------------------------------------------- */
 /**
  * release_memory_range -- release memory previously lmb_reserved
  * @start_pfn: starting physical frame number
@@ -125,7 +253,11 @@ static void release_all (void)
 static int __init phyp_dump_setup(void)
 {
 	struct device_node *rtas;
-	const int *dump_header;
+	const struct phyp_dump_header *dump_header;
+	unsigned long dump_area_start;
+	unsigned long dump_area_length;
+	unsigned long free_area_length;
+	unsigned long start_pfn, nr_pages;
 	int header_len = 0;
 	int rc;
 
@@ -140,22 +272,47 @@ static int __init phyp_dump_setup(void)
 		return -ENOSYS;
 	}
 
-	/* Is there dump data waiting for us? */
+	/* Is there dump data waiting for us? If there isn't,
+	 * then register a new dump area, and release all of
+	 * the rest of the reserved ram.
+	 *
+	 * The /rtas/ibm,kernel-dump rtas node is present only
+	 * if there is dump data waiting for us.
+	 */
 	rtas = of_find_node_by_path("/rtas");
 	dump_header = of_get_property(rtas, "ibm,kernel-dump", &header_len);
+
+	dump_area_length = init_dump_header (&phdr);
+	free_area_length = phyp_dump_info->init_reserve_size - dump_area_length;
+	dump_area_start = phyp_dump_info->init_reserve_start + free_area_length;
+	dump_area_start = dump_area_start & PAGE_MASK; /* align down */
+	free_area_length = dump_area_start - phyp_dump_info->init_reserve_start;
+
 	if (dump_header == NULL) {
-		release_all();
-		return 0;
+		register_dump_area (&phdr, dump_area_start);
+		goto release_mem;
 	}
 
+	/* Don't allow user to release the 256MB scratch area */
+	phyp_dump_info->init_reserve_size = free_area_length;
+
 	/* Should we create a dump_subsys, analogous to s390/ipl.c ? */
 	rc = subsys_create_file(&kernel_subsys, &rr);
 	if (rc) {
 		printk (KERN_ERR "phyp-dump: unable to create sysfs file (%d)\n", rc);
-		release_all();
-		return 0;
+		goto release_mem;
 	}
 
+	/* ToDo: re-register the dump area, for next time. */
+
+	return 0;
+
+release_mem:
+	/* release everything except the top 256 MB scratch area */
+	start_pfn = PFN_DOWN(phyp_dump_info->init_reserve_start);
+	nr_pages = PFN_DOWN(free_area_length);
+	release_memory_range(start_pfn, nr_pages);
+
 	return 0;
 }
 
> documentation explaining what this is  :-) . Yes, its supposed
> to be an improvement over kdump.
> 
> The patches mostly work; a list of open issues / todo list
> is included in the documentation.  It also appears that 
> the not-yet-released firmware versions this was tested 
> on are still, ahem, incomplete; this work is also pending.
> 
> -- Linas & Manish
> _______________________________________________
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> [email-masked]
> https://ozlabs.org/mailman/listinfo/linuxppc-dev