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authorManish Ahuja <ahuja@austin.ibm.com>2008-03-22 10:39:17 +1100
committerPaul Mackerras <paulus@samba.org>2008-03-26 08:44:06 +1100
commitd5a29c7a36958ddec1ae7ab685ce09a002356548 (patch)
tree658282c0e2154e000e46c3fc4fbfd97ccae97fd8
parent6ac26c8a7eb149dbd669cc6cd9b77ffc9cd0d2fb (diff)
[POWERPC] pseries: phyp dump: Use sysfs to release reserved mem
Check to see if there actually is data from a previously crashed kernel waiting. If so, allow user-space tools to grab the data (by reading /proc/kcore). When user-space finishes dumping a section, it must release that memory by writing to sysfs. For example, echo "0x40000000 0x10000000" > /sys/kernel/release_region will release 256MB starting at the 1GB. The released memory becomes free for general use. Signed-off-by: Linas Vepstas <linasvepstas@gmail.com> Signed-off-by: Manish Ahuja <mahuja@us.ibm.com> Signed-off-by: Paul Mackerras <paulus@samba.org>
-rw-r--r--arch/powerpc/platforms/pseries/phyp_dump.c81
1 files changed, 76 insertions, 5 deletions
diff --git a/arch/powerpc/platforms/pseries/phyp_dump.c b/arch/powerpc/platforms/pseries/phyp_dump.c
index 230286cafff..f355f052a56 100644
--- a/arch/powerpc/platforms/pseries/phyp_dump.c
+++ b/arch/powerpc/platforms/pseries/phyp_dump.c
@@ -12,19 +12,24 @@
*/
#include <linux/init.h>
+#include <linux/kobject.h>
#include <linux/mm.h>
+#include <linux/of.h>
#include <linux/pfn.h>
#include <linux/swap.h>
+#include <linux/sysfs.h>
#include <asm/page.h>
#include <asm/phyp_dump.h>
#include <asm/machdep.h>
#include <asm/prom.h>
+#include <asm/rtas.h>
/* Variables, used to communicate data between early boot and late boot */
static struct phyp_dump phyp_dump_vars;
struct phyp_dump *phyp_dump_info = &phyp_dump_vars;
+/* ------------------------------------------------- */
/**
* release_memory_range -- release memory previously lmb_reserved
* @start_pfn: starting physical frame number
@@ -54,18 +59,84 @@ release_memory_range(unsigned long start_pfn, unsigned long nr_pages)
}
}
-static int __init phyp_dump_setup(void)
+/* ------------------------------------------------- */
+/**
+ * sysfs_release_region -- sysfs interface to release memory range.
+ *
+ * Usage:
+ * "echo <start addr> <length> > /sys/kernel/release_region"
+ *
+ * Example:
+ * "echo 0x40000000 0x10000000 > /sys/kernel/release_region"
+ *
+ * will release 256MB starting at 1GB.
+ */
+static ssize_t store_release_region(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ const char *buf, size_t count)
{
+ unsigned long start_addr, length, end_addr;
unsigned long start_pfn, nr_pages;
+ ssize_t ret;
+
+ ret = sscanf(buf, "%lx %lx", &start_addr, &length);
+ if (ret != 2)
+ return -EINVAL;
+
+ /* Range-check - don't free any reserved memory that
+ * wasn't reserved for phyp-dump */
+ if (start_addr < phyp_dump_info->init_reserve_start)
+ start_addr = phyp_dump_info->init_reserve_start;
+
+ end_addr = phyp_dump_info->init_reserve_start +
+ phyp_dump_info->init_reserve_size;
+ if (start_addr+length > end_addr)
+ length = end_addr - start_addr;
+
+ /* Release the region of memory assed in by user */
+ start_pfn = PFN_DOWN(start_addr);
+ nr_pages = PFN_DOWN(length);
+ release_memory_range(start_pfn, nr_pages);
+
+ return count;
+}
+
+static struct kobj_attribute rr = __ATTR(release_region, 0600,
+ NULL, store_release_region);
+
+static int __init phyp_dump_setup(void)
+{
+ struct device_node *rtas;
+ const int *dump_header = NULL;
+ int header_len = 0;
+ int rc;
/* If no memory was reserved in early boot, there is nothing to do */
if (phyp_dump_info->init_reserve_size == 0)
return 0;
- /* Release memory that was reserved in early boot */
- start_pfn = PFN_DOWN(phyp_dump_info->init_reserve_start);
- nr_pages = PFN_DOWN(phyp_dump_info->init_reserve_size);
- release_memory_range(start_pfn, nr_pages);
+ /* Return if phyp dump not supported */
+ if (!phyp_dump_info->phyp_dump_configured)
+ return -ENOSYS;
+
+ /* Is there dump data waiting for us? */
+ rtas = of_find_node_by_path("/rtas");
+ if (rtas) {
+ dump_header = of_get_property(rtas, "ibm,kernel-dump",
+ &header_len);
+ of_node_put(rtas);
+ }
+
+ if (dump_header == NULL)
+ return 0;
+
+ /* Should we create a dump_subsys, analogous to s390/ipl.c ? */
+ rc = sysfs_create_file(kernel_kobj, &rr.attr);
+ if (rc) {
+ printk(KERN_ERR "phyp-dump: unable to create sysfs file (%d)\n",
+ rc);
+ return 0;
+ }
return 0;
}