[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>
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@ -12,19 +12,24 @@
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*/
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#include <linux/init.h>
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#include <linux/kobject.h>
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#include <linux/mm.h>
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#include <linux/of.h>
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#include <linux/pfn.h>
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#include <linux/swap.h>
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#include <linux/sysfs.h>
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#include <asm/page.h>
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#include <asm/phyp_dump.h>
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#include <asm/machdep.h>
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#include <asm/prom.h>
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#include <asm/rtas.h>
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/* Variables, used to communicate data between early boot and late boot */
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static struct phyp_dump phyp_dump_vars;
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struct phyp_dump *phyp_dump_info = &phyp_dump_vars;
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/* ------------------------------------------------- */
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/**
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* release_memory_range -- release memory previously lmb_reserved
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* @start_pfn: starting physical frame number
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@ -54,18 +59,84 @@ release_memory_range(unsigned long start_pfn, unsigned long nr_pages)
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}
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}
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/* ------------------------------------------------- */
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/**
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* sysfs_release_region -- sysfs interface to release memory range.
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*
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* Usage:
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* "echo <start addr> <length> > /sys/kernel/release_region"
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*
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* Example:
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* "echo 0x40000000 0x10000000 > /sys/kernel/release_region"
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*
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* will release 256MB starting at 1GB.
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*/
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static ssize_t store_release_region(struct kobject *kobj,
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struct kobj_attribute *attr,
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const char *buf, size_t count)
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{
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unsigned long start_addr, length, end_addr;
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unsigned long start_pfn, nr_pages;
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ssize_t ret;
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ret = sscanf(buf, "%lx %lx", &start_addr, &length);
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if (ret != 2)
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return -EINVAL;
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/* Range-check - don't free any reserved memory that
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* wasn't reserved for phyp-dump */
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if (start_addr < phyp_dump_info->init_reserve_start)
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start_addr = phyp_dump_info->init_reserve_start;
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end_addr = phyp_dump_info->init_reserve_start +
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phyp_dump_info->init_reserve_size;
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if (start_addr+length > end_addr)
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length = end_addr - start_addr;
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/* Release the region of memory assed in by user */
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start_pfn = PFN_DOWN(start_addr);
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nr_pages = PFN_DOWN(length);
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release_memory_range(start_pfn, nr_pages);
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return count;
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}
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static struct kobj_attribute rr = __ATTR(release_region, 0600,
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NULL, store_release_region);
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static int __init phyp_dump_setup(void)
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{
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unsigned long start_pfn, nr_pages;
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struct device_node *rtas;
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const int *dump_header = NULL;
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int header_len = 0;
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int rc;
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/* If no memory was reserved in early boot, there is nothing to do */
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if (phyp_dump_info->init_reserve_size == 0)
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return 0;
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/* Release memory that was reserved in early boot */
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start_pfn = PFN_DOWN(phyp_dump_info->init_reserve_start);
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nr_pages = PFN_DOWN(phyp_dump_info->init_reserve_size);
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release_memory_range(start_pfn, nr_pages);
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/* Return if phyp dump not supported */
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if (!phyp_dump_info->phyp_dump_configured)
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return -ENOSYS;
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/* Is there dump data waiting for us? */
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rtas = of_find_node_by_path("/rtas");
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if (rtas) {
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dump_header = of_get_property(rtas, "ibm,kernel-dump",
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&header_len);
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of_node_put(rtas);
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}
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if (dump_header == NULL)
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return 0;
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/* Should we create a dump_subsys, analogous to s390/ipl.c ? */
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rc = sysfs_create_file(kernel_kobj, &rr.attr);
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if (rc) {
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printk(KERN_ERR "phyp-dump: unable to create sysfs file (%d)\n",
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rc);
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return 0;
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}
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return 0;
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}
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