Kdump kernel, used for capturing the kernel core image, is supposed
to use only specific memory regions to avoid corrupting the image to
be captured. The regions are crashkernel range - the memory reserved
explicitly for kdump kernel, memory used for the tce-table, the OPAL
region and RTAS region as applicable. Restrict kdump kernel memory
to use only these regions by setting up usable-memory DT property.
Also, tell the kdump kernel to run at the loaded address by setting
the magic word at 0x5c.
Signed-off-by: Hari Bathini <hbathini@xxxxxxxxxxxxx>
Tested-by: Pingfan Liu <piliu@xxxxxxxxxx>
Reviewed-by: Thiago Jung Bauermann <bauerman@xxxxxxxxxxxxx>
---
v5 -> v6:
* Added Reviewed-by tag from Thiago.
* Avoided pass by reference count parameter in add_usable_mem() function
by calculating the range count added from index value before & after it.
* Instead of trying to reinvent the wheel with get_node_path() &
get_node_path_size() functions, used %pOF format as suggested by mpe.
* Used kernel types instead of uint32_t/uint64_t.
* and Dropped 'struct crash_mem *' member & added 'struct crash_mem_range *',
nr_ranges & max_entries fields to 'struct umem_info' to avoid bit of
a clutter in check_realloc_usable_mem() & add_usable_mem() functions.
* Updated the comment as to why 0 till crashk_res.start was needed to be
added to usable memory ranges. Note that kexec-tools also has been
doing the same thing.
v4 -> v5:
* Renamed get_node_pathlen() function to get_node_path_size() and
handled root node separately to avoid off-by-one error in
calculating string size.
* Updated get_node_path() in line with change in get_node_path_size().
v3 -> v4:
* Updated get_node_path() to be an iterative function instead of a
recursive one.
* Added comment explaining why low memory is added to kdump kernel's
usable memory ranges though it doesn't fall in crashkernel region.
* For correctness, added fdt_add_mem_rsv() for the low memory being
added to kdump kernel's usable memory ranges.
* Fixed prop pointer update in add_usable_mem_property() and changed
duple to tuple as suggested by Thiago.
v2 -> v3:
* Unchanged. Added Tested-by tag from Pingfan.
v1 -> v2:
* Fixed off-by-one error while setting up usable-memory properties.
* Updated add_rtas_mem_range() & add_opal_mem_range() callsites based on
the new prototype for these functions.
arch/powerpc/kexec/file_load_64.c | 386 +++++++++++++++++++++++++++++++++++++
1 file changed, 385 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/kexec/file_load_64.c b/arch/powerpc/kexec/file_load_64.c
index d09c7724efa8..f94660874765 100644
--- a/arch/powerpc/kexec/file_load_64.c
+++ b/arch/powerpc/kexec/file_load_64.c
@@ -17,9 +17,23 @@
#include <linux/kexec.h>
#include <linux/of_fdt.h>
#include <linux/libfdt.h>
+#include <linux/of_device.h>
#include <linux/memblock.h>
+#include <linux/slab.h>
+#include <asm/drmem.h>
#include <asm/kexec_ranges.h>
+struct umem_info {
+ u64 *buf; /* data buffer for usable-memory property */
+ u32 size; /* size allocated for the data buffer */
+ u32 max_entries; /* maximum no. of entries */
+ u32 idx; /* index of current entry */
+
+ /* usable memory ranges to look up */
+ unsigned int nr_ranges;
+ const struct crash_mem_range *ranges;
+};
+
const struct kexec_file_ops * const kexec_file_loaders[] = {
&kexec_elf64_ops,
NULL
@@ -74,6 +88,44 @@ static int get_exclude_memory_ranges(struct crash_mem **mem_ranges)
return ret;
}
+/**
+ * get_usable_memory_ranges - Get usable memory ranges. This list includes
+ * regions like crashkernel, opal/rtas & tce-table,
+ * that kdump kernel could use.
+ * @mem_ranges: Range list to add the memory ranges to.
+ *
+ * Returns 0 on success, negative errno on error.
+ */
+static int get_usable_memory_ranges(struct crash_mem **mem_ranges)
+{
+ int ret;
+
+ /*
+ * Early boot failure observed on guests when low memory (first memory
+ * block?) is not added to usable memory. So, add [0, crashk_res.end]
+ * instead of [crashk_res.start, crashk_res.end] to workaround it.
+ * Also, crashed kernel's memory must be added to reserve map to
+ * avoid kdump kernel from using it.
+ */
+ ret = add_mem_range(mem_ranges, 0, crashk_res.end + 1);
+ if (ret)
+ goto out;
+
+ ret = add_rtas_mem_range(mem_ranges);
+ if (ret)
+ goto out;
+
+ ret = add_opal_mem_range(mem_ranges);
+ if (ret)
+ goto out;
+
+ ret = add_tce_mem_ranges(mem_ranges);
+out:
+ if (ret)
+ pr_err("Failed to setup usable memory ranges\n");
+ return ret;
+}
+
/**
* __locate_mem_hole_top_down - Looks top down for a large enough memory hole
* in the memory regions between buf_min & buf_max
@@ -273,6 +325,286 @@ static int locate_mem_hole_bottom_up_ppc64(struct kexec_buf *kbuf,
return ret;
}
+/**
+ * check_realloc_usable_mem - Reallocate buffer if it can't accommodate entries
+ * @um_info: Usable memory buffer and ranges info.
+ * @cnt: No. of entries to accommodate.
+ *
+ * Frees up the old buffer if memory reallocation fails.
+ *
+ * Returns buffer on success, NULL on error.
+ */
+static u64 *check_realloc_usable_mem(struct umem_info *um_info, int cnt)
+{
+ u32 new_size;
+ u64 *tbuf;
+
+ if ((um_info->idx + cnt) <= um_info->max_entries)
+ return um_info->buf;
+
+ new_size = um_info->size + MEM_RANGE_CHUNK_SZ;
+ tbuf = krealloc(um_info->buf, new_size, GFP_KERNEL);
+ if (tbuf) {
+ um_info->buf = tbuf;
+ um_info->size = new_size;
+ um_info->max_entries = (um_info->size / sizeof(u64));
+ }
+
+ return tbuf;
+}
+
+/**
+ * add_usable_mem - Add the usable memory ranges within the given memory range
+ * to the buffer
+ * @um_info: Usable memory buffer and ranges info.
+ * @base: Base address of memory range to look for.
+ * @end: End address of memory range to look for.
+ *
+ * Returns 0 on success, negative errno on error.
+ */
+static int add_usable_mem(struct umem_info *um_info, u64 base, u64 end)
+{
+ u64 loc_base, loc_end;
+ bool add;
+ int i;
+
+ for (i = 0; i < um_info->nr_ranges; i++) {
+ add = false;
+ loc_base = um_info->ranges[i].start;
+ loc_end = um_info->ranges[i].end;
+ if (loc_base >= base && loc_end <= end)
+ add = true;
+ else if (base < loc_end && end > loc_base) {
+ if (loc_base < base)
+ loc_base = base;
+ if (loc_end > end)
+ loc_end = end;
+ add = true;
+ }
+
+ if (add) {
+ if (!check_realloc_usable_mem(um_info, 2))
+ return -ENOMEM;
+
+ um_info->buf[um_info->idx++] = cpu_to_be64(loc_base);
+ um_info->buf[um_info->idx++] =
+ cpu_to_be64(loc_end - loc_base + 1);
+ }
+ }
+
+ return 0;
+}
+
+/**
+ * kdump_setup_usable_lmb - This is a callback function that gets called by
+ * walk_drmem_lmbs for every LMB to set its
+ * usable memory ranges.
+ * @lmb: LMB info.
+ * @usm: linux,drconf-usable-memory property value.
+ * @data: Pointer to usable memory buffer and ranges info.
+ *
+ * Returns 0 on success, negative errno on error.
+ */
+static int kdump_setup_usable_lmb(struct drmem_lmb *lmb, const __be32 **usm,
+ void *data)
+{
+ struct umem_info *um_info;
+ int tmp_idx, ret;
+ u64 base, end;
+
+ /*
+ * kdump load isn't supported on kernels already booted with
+ * linux,drconf-usable-memory property.
+ */
+ if (*usm) {
+ pr_err("linux,drconf-usable-memory property already exists!");
+ return -EINVAL;
+ }
+
+ um_info = data;
+ tmp_idx = um_info->idx;
+ if (!check_realloc_usable_mem(um_info, 1))
+ return -ENOMEM;
+
+ um_info->idx++;
+ base = lmb->base_addr;
+ end = base + drmem_lmb_size() - 1;
+ ret = add_usable_mem(um_info, base, end);
+ if (!ret) {
+ /*
+ * Update the no. of ranges added. Two entries (base & size)
+ * for every range added.
+ */
+ um_info->buf[tmp_idx] =
+ cpu_to_be64((um_info->idx - tmp_idx - 1) / 2);
+ }
+
+ return ret;
+}
+
+#define NODE_PATH_LEN 256
+/**
+ * add_usable_mem_property - Add usable memory property for the given
+ * memory node.
+ * @fdt: Flattened device tree for the kdump kernel.
+ * @dn: Memory node.
+ * @um_info: Usable memory buffer and ranges info.
+ *
+ * Returns 0 on success, negative errno on error.
+ */
+static int add_usable_mem_property(void *fdt, struct device_node *dn,
+ struct umem_info *um_info)
+{
+ int n_mem_addr_cells, n_mem_size_cells, node;
+ char path[NODE_PATH_LEN];
+ int i, len, ranges, ret;
+ const __be32 *prop;
+ u64 base, end;
+
+ of_node_get(dn);
+
+ if (snprintf(path, NODE_PATH_LEN, "%pOF", dn) > (NODE_PATH_LEN - 1)) {
+ pr_err("Buffer (%d) too small for memory node: %pOF\n",
+ NODE_PATH_LEN, dn);
+ return -EOVERFLOW;
+ }
+ pr_debug("Memory node path: %s\n", path);
+
+ /* Now that we know the path, find its offset in kdump kernel's fdt */
+ node = fdt_path_offset(fdt, path);
+ if (node < 0) {
+ pr_err("Malformed device tree: error reading %s\n", path);
+ ret = -EINVAL;
+ goto out;
+ }
+
+ /* Get the address & size cells */
+ n_mem_addr_cells = of_n_addr_cells(dn);
+ n_mem_size_cells = of_n_size_cells(dn);
+ pr_debug("address cells: %d, size cells: %d\n", n_mem_addr_cells,
+ n_mem_size_cells);
+
+ um_info->idx = 0;
+ if (!check_realloc_usable_mem(um_info, 2)) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ prop = of_get_property(dn, "reg", &len);
+ if (!prop || len <= 0) {
+ ret = 0;
+ goto out;
+ }
+
+ /*
+ * "reg" property represents sequence of (addr,size) tuples
+ * each representing a memory range.
+ */
+ ranges = (len >> 2) / (n_mem_addr_cells + n_mem_size_cells);
+
+ for (i = 0; i < ranges; i++) {
+ base = of_read_number(prop, n_mem_addr_cells);
+ prop += n_mem_addr_cells;
+ end = base + of_read_number(prop, n_mem_size_cells) - 1;
+ prop += n_mem_size_cells;
+
+ ret = add_usable_mem(um_info, base, end);
+ if (ret)
+ goto out;
+ }
+
+ /*
+ * No kdump kernel usable memory found in this memory node.
+ * Write (0,0) tuple in linux,usable-memory property for
+ * this region to be ignored.
+ */
+ if (um_info->idx == 0) {
+ um_info->buf[0] = 0;
+ um_info->buf[1] = 0;
+ um_info->idx = 2;
+ }
+
+ ret = fdt_setprop(fdt, node, "linux,usable-memory", um_info->buf,
+ (um_info->idx * sizeof(u64)));
+
+out:
+ of_node_put(dn);
+ return ret;
+}
+
+
+/**
+ * update_usable_mem_fdt - Updates kdump kernel's fdt with linux,usable-memory
+ * and linux,drconf-usable-memory DT properties as
+ * appropriate to restrict its memory usage.
+ * @fdt: Flattened device tree for the kdump kernel.
+ * @usable_mem: Usable memory ranges for kdump kernel.
+ *
+ * Returns 0 on success, negative errno on error.
+ */
+static int update_usable_mem_fdt(void *fdt, struct crash_mem *usable_mem)
+{
+ struct umem_info um_info;
+ struct device_node *dn;
+ int node, ret = 0;
+
+ if (!usable_mem) {
+ pr_err("Usable memory ranges for kdump kernel not found\n");
+ return -ENOENT;
+ }
+
+ node = fdt_path_offset(fdt, "/ibm,dynamic-reconfiguration-memory");
+ if (node == -FDT_ERR_NOTFOUND)
+ pr_debug("No dynamic reconfiguration memory found\n");
+ else if (node < 0) {
+ pr_err("Malformed device tree: error reading /ibm,dynamic-reconfiguration-memory.\n");
+ return -EINVAL;
+ }
+
+ um_info.buf = NULL;
+ um_info.size = 0;
+ um_info.max_entries = 0;
+ um_info.idx = 0;
+ /* Memory ranges to look up */
+ um_info.ranges = &(usable_mem->ranges[0]);
+ um_info.nr_ranges = usable_mem->nr_ranges;
+
+ dn = of_find_node_by_path("/ibm,dynamic-reconfiguration-memory");
+ if (dn) {
+ ret = walk_drmem_lmbs(dn, &um_info, kdump_setup_usable_lmb);
+ of_node_put(dn);
+
+ if (ret) {
+ pr_err("Could not setup linux,drconf-usable-memory property for kdump\n");
+ goto out;
+ }
+
+ ret = fdt_setprop(fdt, node, "linux,drconf-usable-memory",
+ um_info.buf, (um_info.idx * sizeof(u64)));
+ if (ret) {
+ pr_err("Failed to update fdt with linux,drconf-usable-memory property");
+ goto out;
+ }
+ }
+
+ /*
+ * Walk through each memory node and set linux,usable-memory property
+ * for the corresponding node in kdump kernel's fdt.
+ */
+ for_each_node_by_type(dn, "memory") {
+ ret = add_usable_mem_property(fdt, dn, &um_info);
+ if (ret) {
+ pr_err("Failed to set linux,usable-memory property for %s node",
+ dn->full_name);
+ goto out;
+ }
+ }
+
+out:
+ kfree(um_info.buf);
+ return ret;
+}
+
/**
* setup_purgatory_ppc64 - initialize PPC64 specific purgatory's global
* variables and call setup_purgatory() to initialize
@@ -293,6 +625,25 @@ int setup_purgatory_ppc64(struct kimage *image, const void *slave_code,
ret = setup_purgatory(image, slave_code, fdt, kernel_load_addr,
fdt_load_addr);
+ if (ret)
+ goto out;
+
+ if (image->type == KEXEC_TYPE_CRASH) {
+ u32 my_run_at_load = 1;
+
+ /*
+ * Tell relocatable kernel to run at load address
+ * via the word meant for that at 0x5c.
+ */
+ ret = kexec_purgatory_get_set_symbol(image, "run_at_load",
+ &my_run_at_load,
+ sizeof(my_run_at_load),
+ false);
+ if (ret)
+ goto out;
+ }
+
+out:
if (ret)
pr_err("Failed to setup purgatory symbols");
return ret;
@@ -314,7 +665,40 @@ int setup_new_fdt_ppc64(const struct kimage *image, void *fdt,
unsigned long initrd_load_addr,
unsigned long initrd_len, const char *cmdline)
{
- return setup_new_fdt(image, fdt, initrd_load_addr, initrd_len, cmdline);
+ struct crash_mem *umem = NULL;
+ int ret;
+
+ ret = setup_new_fdt(image, fdt, initrd_load_addr, initrd_len, cmdline);
+ if (ret)
+ goto out;
+
+ /*
+ * Restrict memory usage for kdump kernel by setting up
+ * usable memory ranges.
+ */
+ if (image->type == KEXEC_TYPE_CRASH) {
+ ret = get_usable_memory_ranges(&umem);
+ if (ret)
+ goto out;
+
+ ret = update_usable_mem_fdt(fdt, umem);
+ if (ret) {
+ pr_err("Error setting up usable-memory property for kdump kernel\n");
+ goto out;
+ }
+
+ /* Ensure we don't touch crashed kernel's memory */
+ ret = fdt_add_mem_rsv(fdt, 0, crashk_res.start);
+ if (ret) {
+ pr_err("Error reserving crash memory: %s\n",
+ fdt_strerror(ret));
+ goto out;
+ }
+ }
+
+out:
+ kfree(umem);
+ return ret;
}
/**
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