[PATCH v8 10/13] powerpc: Add code to work with device trees in kexec_file_load.

Thiago Jung Bauermann
2016-09-05T22:23:11Z

kexec_file_load needs to set up the device tree that will be used
by the next kernel and check whether it provides a console
that can be used by the purgatory.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
arch/powerpc/include/asm/kexec.h | 3 +
arch/powerpc/kernel/machine_kexec_64.c | 221 +++++++++++++++++++++++++++++++++
2 files changed, 224 insertions(+)

diff --git a/arch/powerpc/include/asm/kexec.h b/arch/powerpc/include/asm/kexec.h
index 0c7e020d935a..73f88b5f9bd1 100644
--- a/arch/powerpc/include/asm/kexec.h
+++ b/arch/powerpc/include/asm/kexec.h
@@ -96,6 +96,9 @@ int setup_purgatory(struct kimage *image, const void *slave_code,
const void *fdt, unsigned long kernel_load_addr,
unsigned long fdt_load_addr, unsigned long stack_top,
int debug);
+int setup_new_fdt(void *fdt, unsigned long initrd_load_addr,
+ unsigned long initrd_len, const char *cmdline);
+bool find_debug_console(const void *fdt);
#endif /* CONFIG_KEXEC_FILE */

#else /* !CONFIG_KEXEC_CORE */
diff --git a/arch/powerpc/kernel/machine_kexec_64.c b/arch/powerpc/kernel/machine_kexec_64.c
index 1e678dc5096a..31c5090705e0 100644
--- a/arch/powerpc/kernel/machine_kexec_64.c
+++ b/arch/powerpc/kernel/machine_kexec_64.c
@@ -683,4 +683,225 @@ int setup_purgatory(struct kimage *image, const void *slave_code,
return 0;
}

+/*
+ * setup_new_fdt() - modify /chosen and memory reservation for the next kernel
+ * @fdt:
+ * @initrd_load_addr: Address where the next initrd will be loaded.
+ * @initrd_len: Size of the next initrd, or 0 if there will be none.
+ * @cmdline: Command line for the next kernel, or NULL if there will
+ * be none.
+ *
+ * Return: 0 on success, or negative errno on error.
+ */
+int setup_new_fdt(void *fdt, unsigned long initrd_load_addr,
+ unsigned long initrd_len, const char *cmdline)
+{
+ uint64_t oldfdt_addr;
+ int i, ret, chosen_node;
+ const void *prop;
+
+ /* Remove memory reservation for the current device tree. */
+ oldfdt_addr = __pa(initial_boot_params);
+ for (i = 0; i < fdt_num_mem_rsv(fdt); i++) {
+ uint64_t rsv_start, rsv_size;
+
+ ret = fdt_get_mem_rsv(fdt, i, &rsv_start, &rsv_size);
+ if (ret) {
+ pr_err("Malformed device tree.\n");
+ return -EINVAL;
+ }
+
+ if (rsv_start == oldfdt_addr &&
+ rsv_size == fdt_totalsize(initial_boot_params)) {
+ ret = fdt_del_mem_rsv(fdt, i);
+ if (ret) {
+ pr_err("Error deleting fdt reservation.\n");
+ return -EINVAL;
+ }
+
+ pr_debug("Removed old device tree reservation.\n");
+ break;
+ }
+ }
+
+ chosen_node = fdt_path_offset(fdt, "/chosen");
+ if (chosen_node == -FDT_ERR_NOTFOUND) {
+ chosen_node = fdt_add_subnode(fdt, fdt_path_offset(fdt, "/"),
+ "chosen");
+ if (chosen_node < 0) {
+ pr_err("Error creating /chosen.\n");
+ return -EINVAL;
+ }
+ } else if (chosen_node < 0) {
+ pr_err("Malformed device tree: error reading /chosen.\n");
+ return -EINVAL;
+ }
+
+ /* Did we boot using an initrd? */
+ prop = fdt_getprop(fdt, chosen_node, "linux,initrd-start", NULL);
+ if (prop) {
+ uint64_t tmp_start, tmp_end, tmp_size, tmp_sizepg;
+
+ tmp_start = fdt64_to_cpu(*((const fdt64_t *) prop));
+
+ prop = fdt_getprop(fdt, chosen_node, "linux,initrd-end", NULL);
+ if (!prop) {
+ pr_err("Malformed device tree.\n");
+ return -EINVAL;
+ }
+ tmp_end = fdt64_to_cpu(*((const fdt64_t *) prop));
+
+ /*
+ * kexec reserves exact initrd size, while firmware may
+ * reserve a multiple of PAGE_SIZE, so check for both.
+ */
+ tmp_size = tmp_end - tmp_start;
+ tmp_sizepg = round_up(tmp_size, PAGE_SIZE);
+
+ /* Remove memory reservation for the current initrd. */
+ for (i = 0; i < fdt_num_mem_rsv(fdt); i++) {
+ uint64_t rsv_start, rsv_size;
+
+ ret = fdt_get_mem_rsv(fdt, i, &rsv_start, &rsv_size);
+ if (ret) {
+ pr_err("Malformed device tree.\n");
+ return -EINVAL;
+ }
+
+ if (rsv_start == tmp_start &&
+ (rsv_size == tmp_size || rsv_size == tmp_sizepg)) {
+ ret = fdt_del_mem_rsv(fdt, i);
+ if (ret) {
+ pr_err("Error deleting fdt reservation.\n");
+ return -EINVAL;
+ }
+ pr_debug("Removed old initrd reservation.\n");
+
+ break;
+ }
+ }
+
+ /* If there's no new initrd, delete the old initrd's info. */
+ if (initrd_len == 0) {
+ ret = fdt_delprop(fdt, chosen_node,
+ "linux,initrd-start");
+ if (ret) {
+ pr_err("Error deleting linux,initrd-start.\n");
+ return -EINVAL;
+ }
+
+ ret = fdt_delprop(fdt, chosen_node, "linux,initrd-end");
+ if (ret) {
+ pr_err("Error deleting linux,initrd-end.\n");
+ return -EINVAL;
+ }
+ }
+ }
+
+ if (initrd_len) {
+ ret = fdt_setprop_u64(fdt, chosen_node,
+ "linux,initrd-start",
+ initrd_load_addr);
+ if (ret < 0) {
+ pr_err("Error setting up the new device tree.\n");
+ return -EINVAL;
+ }
+
+ /* initrd-end is the first address after the initrd image. */
+ ret = fdt_setprop_u64(fdt, chosen_node, "linux,initrd-end",
+ initrd_load_addr + initrd_len);
+ if (ret < 0) {
+ pr_err("Error setting up the new device tree.\n");
+ return -EINVAL;
+ }
+
+ ret = fdt_add_mem_rsv(fdt, initrd_load_addr, initrd_len);
+ if (ret) {
+ pr_err("Error reserving initrd memory: %s\n",
+ fdt_strerror(ret));
+ return -EINVAL;
+ }
+ }
+
+ if (cmdline != NULL) {
+ ret = fdt_setprop_string(fdt, chosen_node, "bootargs", cmdline);
+ if (ret < 0) {
+ pr_err("Error setting up the new device tree.\n");
+ return -EINVAL;
+ }
+ } else {
+ ret = fdt_delprop(fdt, chosen_node, "bootargs");
+ if (ret && ret != -FDT_ERR_NOTFOUND) {
+ pr_err("Error deleting bootargs.\n");
+ return -EINVAL;
+ }
+ }
+
+ ret = fdt_setprop(fdt, chosen_node, "linux,booted-from-kexec", NULL, 0);
+ if (ret) {
+ pr_err("Error setting up the new device tree.\n");
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+/**
+ * find_debug_console() - find out whether there is a console for the purgatory
+ * @fdt: Flattened device tree to search.
+ */
+bool find_debug_console(const void *fdt)
+{
+ int len;
+ int console_node, chosen_node;
+ const void *prop, *colon;
+
+ chosen_node = fdt_path_offset(fdt, "/chosen");
+ if (chosen_node < 0) {
+ pr_err("Malformed device tree: /chosen not found.\n");
+ return false;
+ }
+
+ prop = fdt_getprop(fdt, chosen_node, "stdout-path", &len);
+ if (prop == NULL) {
+ if (len == -FDT_ERR_NOTFOUND) {
+ prop = fdt_getprop(fdt, chosen_node,
+ "linux,stdout-path", &len);
+ if (prop == NULL) {
+ pr_debug("Unable to find [linux,]stdout-path.\n");
+ return false;
+ }
+ } else {
+ pr_debug("Error finding console: %s\n",
+ fdt_strerror(len));
+ return false;
+ }
+ }
+
+ /*
+ * stdout-path can have a ':' separating the path from device-specific
+ * information, so we should only consider what's before it.
+ */
+ colon = strchr(prop, ':');
+ if (colon != NULL)
+ len = colon - prop;
+ else
+ len -= 1; /* Ignore the terminating NUL. */
+
+ console_node = fdt_path_offset_namelen(fdt, prop, len);
+ if (console_node < 0) {
+ pr_debug("Error finding console: %s\n",
+ fdt_strerror(console_node));
+ return false;
+ }
+
+ if (fdt_node_check_compatible(fdt, console_node, "hvterm1") == 0)
+ return true;
+ else if (fdt_node_check_compatible(fdt, console_node,
+ "hvterm-protocol") == 0)
+ return true;
+
+ return false;
+}
+
#endif /* CONFIG_KEXEC_FILE */
--
1.9.1