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 <hbath...@linux.ibm.com> Tested-by: Pingfan Liu <pi...@redhat.com> --- 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 | 472 +++++++++++++++++++++++++++++++++++++ 1 file changed, 471 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/kexec/file_load_64.c b/arch/powerpc/kexec/file_load_64.c index 2df6f42..71c1ba7 100644 --- a/arch/powerpc/kexec/file_load_64.c +++ b/arch/powerpc/kexec/file_load_64.c @@ -17,9 +17,21 @@ #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 { + uint64_t *buf; /* data buffer for usable-memory property */ + uint32_t idx; /* current index */ + uint32_t size; /* size allocated for the data buffer */ + + /* usable memory ranges to look up */ + const struct crash_mem *umrngs; +}; + const struct kexec_file_ops * const kexec_file_loaders[] = { &kexec_elf64_ops, NULL @@ -75,6 +87,42 @@ static int get_exclude_memory_ranges(struct crash_mem **mem_ranges) } /** + * 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; + + /* + * prom code doesn't take kindly to missing low memory. So, add + * [0, crashk_res.end] instead of [crashk_res.start, crashk_res.end] + * to keep it happy. + */ + 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 * for the buffer. If found, sets kbuf->mem. @@ -274,6 +322,376 @@ static int locate_mem_hole_bottom_up_ppc64(struct kexec_buf *kbuf, } /** + * 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 uint64_t *check_realloc_usable_mem(struct umem_info *um_info, int cnt) +{ + void *tbuf; + + if (um_info->size >= + ((um_info->idx + cnt) * sizeof(*(um_info->buf)))) + return um_info->buf; + + um_info->size += MEM_RANGE_CHUNK_SZ; + tbuf = krealloc(um_info->buf, um_info->size, GFP_KERNEL); + if (!tbuf) { + um_info->size -= MEM_RANGE_CHUNK_SZ; + return NULL; + } + + memset(tbuf + um_info->idx, 0, MEM_RANGE_CHUNK_SZ); + 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. + * @cnt: No. of usable memory ranges added to buffer. + * + * Returns 0 on success, negative errno on error. + */ +static int add_usable_mem(struct umem_info *um_info, uint64_t base, + uint64_t end, int *cnt) +{ + uint64_t loc_base, loc_end, *buf; + const struct crash_mem *umrngs; + int i, add; + + *cnt = 0; + umrngs = um_info->umrngs; + for (i = 0; i < umrngs->nr_ranges; i++) { + add = 0; + loc_base = umrngs->ranges[i].start; + loc_end = umrngs->ranges[i].end; + if (loc_base >= base && loc_end <= end) + add = 1; + else if (base < loc_end && end > loc_base) { + if (loc_base < base) + loc_base = base; + if (loc_end > end) + loc_end = end; + add = 1; + } + + if (add) { + buf = check_realloc_usable_mem(um_info, 2); + if (!buf) + return -ENOMEM; + + um_info->buf = buf; + buf[um_info->idx++] = cpu_to_be64(loc_base); + buf[um_info->idx++] = + cpu_to_be64(loc_end - loc_base + 1); + (*cnt)++; + } + } + + 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; + uint64_t base, end, *buf; + int cnt, tmp_idx, ret; + + /* + * 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; + buf = check_realloc_usable_mem(um_info, 1); + if (!buf) + return -ENOMEM; + + um_info->idx++; + um_info->buf = buf; + base = lmb->base_addr; + end = base + drmem_lmb_size() - 1; + ret = add_usable_mem(um_info, base, end, &cnt); + if (!ret) + um_info->buf[tmp_idx] = cpu_to_be64(cnt); + + return ret; +} + +/** + * get_node_pathlen - Get the full path length of the given node. + * @dn: Node. + * + * Also, counts '/' at the end of the path. + * For example, /memory@0 will be "/memory@0/\0" => 11 bytes. + * + * Returns the string length of the node's full path. + */ +static int get_node_pathlen(struct device_node *dn) +{ + int len = 0; + + if (!dn) + return 0; + + while (dn) { + len += strlen(dn->full_name) + 1; + dn = dn->parent; + } + + return len + 1; +} + +/** + * get_node_path - Get the full path of the given node. + * @node: Device node. + * + * Allocates buffer for node path. The caller must free the buffer + * after use. + * + * Returns buffer with path on success, NULL otherwise. + */ +static char *get_node_path(struct device_node *node) +{ + struct device_node *dn; + int len, idx, nlen; + char *path = NULL; + char end_char; + + if (!node) + goto err; + + /* + * Get the path length first and use it to iteratively build the path + * from node to root. + */ + len = get_node_pathlen(node); + + /* Allocate memory for node path */ + path = kzalloc(ALIGN(len, 8), GFP_KERNEL); + if (!path) + goto err; + + /* + * Iteratively update path from node to root by decrementing + * index appropriately. + * + * Also, add %NUL at the end of node & '/' at the end of all its + * parent nodes. + */ + dn = node; + path[0] = '/'; + idx = len - 1; + end_char = '\0'; + while (dn->parent) { + path[--idx] = end_char; + end_char = '/'; + + nlen = strlen(dn->full_name); + idx -= nlen; + memcpy(path + idx, dn->full_name, nlen); + + dn = dn->parent; + } + + return path; +err: + kfree(path); + return NULL; +} + +/** + * 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; + int i, len, ranges, cnt, ret; + uint64_t base, end, *buf; + const __be32 *prop; + char *pathname; + + of_node_get(dn); + + /* Get the full path of the memory node */ + pathname = get_node_path(dn); + if (!pathname) { + ret = -ENOMEM; + goto out; + } + pr_debug("Memory node path: %s\n", pathname); + + /* Now that we know the path, find its offset in kdump kernel's fdt */ + node = fdt_path_offset(fdt, pathname); + if (node < 0) { + pr_err("Malformed device tree: error reading %s\n", + pathname); + 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; + buf = check_realloc_usable_mem(um_info, 2); + if (!buf) { + ret = -ENOMEM; + goto out; + } + + um_info->buf = buf; + + 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, &cnt); + if (ret) { + ret = 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(*(um_info->buf)))); + +out: + kfree(pathname); + 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.size = 0; + um_info.idx = 0; + um_info.buf = NULL; + um_info.umrngs = usable_mem; + + 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(*(um_info.buf)))); + 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 * common global variable. @@ -294,6 +712,25 @@ 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) { + uint32_t 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 +751,40 @@ 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; } /** _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec