[PATCH v5 3/5] powerpc: kexec_file: Add buffer hand-over support for the next kernel
Thiago Jung Bauermann
bauerman at linux.vnet.ibm.com
Wed Sep 14 17:54:48 PDT 2016
The buffer hand-over mechanism allows the currently running kernel to pass
data to kernel that will be kexec'd via a kexec segment. The second kernel
can check whether the previous kernel sent data and retrieve it.
This is the architecture-specific part.
Signed-off-by: Thiago Jung Bauermann <bauerman at linux.vnet.ibm.com>
---
arch/powerpc/include/asm/kexec.h | 12 +-
arch/powerpc/kernel/kexec_elf_64.c | 2 +-
arch/powerpc/kernel/machine_kexec_64.c | 274 +++++++++++++++++++++++++++------
3 files changed, 240 insertions(+), 48 deletions(-)
diff --git a/arch/powerpc/include/asm/kexec.h b/arch/powerpc/include/asm/kexec.h
index 73f88b5f9bd1..b8e32194ce63 100644
--- a/arch/powerpc/include/asm/kexec.h
+++ b/arch/powerpc/include/asm/kexec.h
@@ -92,12 +92,20 @@ static inline bool kdump_in_progress(void)
}
#ifdef CONFIG_KEXEC_FILE
+#define ARCH_HAS_KIMAGE_ARCH
+
+struct kimage_arch {
+ phys_addr_t handover_buffer_addr;
+ unsigned long handover_buffer_size;
+};
+
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);
+int setup_new_fdt(const struct kimage *image, 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 */
diff --git a/arch/powerpc/kernel/kexec_elf_64.c b/arch/powerpc/kernel/kexec_elf_64.c
index 3cc8ebce1a86..0c576e300384 100644
--- a/arch/powerpc/kernel/kexec_elf_64.c
+++ b/arch/powerpc/kernel/kexec_elf_64.c
@@ -208,7 +208,7 @@ void *elf64_load(struct kimage *image, char *kernel_buf,
goto out;
}
- ret = setup_new_fdt(fdt, initrd_load_addr, initrd_len, cmdline);
+ ret = setup_new_fdt(image, fdt, initrd_load_addr, initrd_len, cmdline);
if (ret)
goto out;
diff --git a/arch/powerpc/kernel/machine_kexec_64.c b/arch/powerpc/kernel/machine_kexec_64.c
index 3879b6d91c0b..d6077898200a 100644
--- a/arch/powerpc/kernel/machine_kexec_64.c
+++ b/arch/powerpc/kernel/machine_kexec_64.c
@@ -489,6 +489,77 @@ int arch_kimage_file_post_load_cleanup(struct kimage *image)
return image->fops->cleanup(image->image_loader_data);
}
+bool kexec_can_hand_over_buffer(void)
+{
+ return true;
+}
+
+int arch_kexec_add_handover_buffer(struct kimage *image,
+ unsigned long load_addr, unsigned long size)
+{
+ image->arch.handover_buffer_addr = load_addr;
+ image->arch.handover_buffer_size = size;
+
+ return 0;
+}
+
+int kexec_get_handover_buffer(void **addr, unsigned long *size)
+{
+ int ret;
+ u64 start_addr, end_addr;
+
+ ret = of_property_read_u64(of_chosen,
+ "linux,kexec-handover-buffer-start",
+ &start_addr);
+ if (ret == -EINVAL)
+ return -ENOENT;
+ else if (ret)
+ return -EINVAL;
+
+ ret = of_property_read_u64(of_chosen, "linux,kexec-handover-buffer-end",
+ &end_addr);
+ if (ret == -EINVAL)
+ return -ENOENT;
+ else if (ret)
+ return -EINVAL;
+
+ *addr = __va(start_addr);
+ /* -end is the first address after the buffer. */
+ *size = end_addr - start_addr;
+
+ return 0;
+}
+
+int kexec_free_handover_buffer(void)
+{
+ int ret;
+ void *addr;
+ unsigned long size;
+ struct property *prop;
+
+ ret = kexec_get_handover_buffer(&addr, &size);
+ if (ret)
+ return ret;
+
+ ret = memblock_free(__pa(addr), size);
+ if (ret)
+ return ret;
+
+ prop = of_find_property(of_chosen, "linux,kexec-handover-buffer-start",
+ NULL);
+ ret = of_remove_property(of_chosen, prop);
+ if (ret)
+ return ret;
+
+ prop = of_find_property(of_chosen, "linux,kexec-handover-buffer-end",
+ NULL);
+ ret = of_remove_property(of_chosen, prop);
+ if (ret)
+ return ret;
+
+ return 0;
+}
+
/**
* arch_kexec_walk_mem() - call func(data) for each unreserved memory block
* @kbuf: Context info for the search. Also passed to @func.
@@ -686,26 +757,16 @@ 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.
+/**
+ * delete_fdt_mem_rsv() - delete memory reservation with given address and size
*
* 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)
+static int delete_fdt_mem_rsv(void *fdt, uint64_t start, uint64_t size)
{
- uint64_t oldfdt_addr;
- int i, ret, chosen_node;
- const void *prop;
+ int i, ret, num_rsvs = fdt_num_mem_rsv(fdt);
- /* Remove memory reservation for the current device tree. */
- oldfdt_addr = __pa(initial_boot_params);
- for (i = 0; i < fdt_num_mem_rsv(fdt); i++) {
+ for (i = 0; i < num_rsvs; i++) {
uint64_t rsv_start, rsv_size;
ret = fdt_get_mem_rsv(fdt, i, &rsv_start, &rsv_size);
@@ -714,19 +775,152 @@ int setup_new_fdt(void *fdt, unsigned long initrd_load_addr,
return -EINVAL;
}
- if (rsv_start == oldfdt_addr &&
- rsv_size == fdt_totalsize(initial_boot_params)) {
+ if (rsv_start == start && rsv_size == size) {
ret = fdt_del_mem_rsv(fdt, i);
if (ret) {
- pr_err("Error deleting fdt reservation.\n");
+ pr_err("Error deleting device tree reservation.\n");
return -EINVAL;
}
- pr_debug("Removed old device tree reservation.\n");
- break;
+ return 0;
}
}
+ return -ENOENT;
+}
+
+/**
+ * setup_handover_buffer() - add handover buffer information to the fdt
+ * @image: kexec image being loaded.
+ * @fdt: Flattened device tree for the next kernel.
+ * @chosen_node: Offset to the chosen node.
+ *
+ * Return: 0 on success, or negative errno on error.
+ */
+static int setup_handover_buffer(const struct kimage *image, void *fdt,
+ int chosen_node)
+{
+ int ret;
+ const void *prop;
+
+ /* Did we receive a buffer from the previous kernel? */
+ prop = fdt_getprop(fdt, chosen_node,
+ "linux,kexec-handover-buffer-start", NULL);
+ if (prop) {
+ u64 orig_start, orig_end;
+ unsigned long size;
+ void *addr;
+
+ orig_start = fdt64_to_cpu(*((const fdt64_t *) prop));
+
+ prop = fdt_getprop(fdt, chosen_node,
+ "linux,kexec-handover-buffer-end", NULL);
+ if (!prop) {
+ pr_err("Malformed device tree.\n");
+ return -EINVAL;
+ }
+ orig_end = fdt64_to_cpu(*((const fdt64_t *) prop));
+
+ /* Did we free the hand-over buffer from the previous kernel? */
+ ret = kexec_get_handover_buffer(&addr, &size);
+ if (ret == -ENOENT)
+ addr = NULL;
+ else if (ret)
+ return ret;
+
+ /*
+ * If we received a buffer from the previous kernel but deleted
+ * it from the live DT, or if we have a new buffer for the next
+ * kernel then we should remove the memory reservation from
+ * the FDT.
+ */
+ if (addr == NULL || image->arch.handover_buffer_addr != 0) {
+ ret = delete_fdt_mem_rsv(fdt, orig_start,
+ orig_end - orig_start);
+ if (ret == 0)
+ pr_debug("Removed old hand-over buffer reservation.\n");
+ else if (ret != -ENOENT)
+ return ret;
+ }
+
+ /*
+ * If we received a buffer from the previous kernel but deleted
+ * it from the live DT and we have no buffer for the next kernel
+ * then we should remove the hand-over buffer properties from
+ * the FDT.
+ */
+ if (addr == NULL && image->arch.handover_buffer_addr == 0) {
+ ret = fdt_delprop(fdt, chosen_node,
+ "linux,kexec-handover-buffer-start");
+ if (ret) {
+ pr_err("Error setting up the new device tree.\n");
+ return -EINVAL;
+ }
+
+ ret = fdt_delprop(fdt, chosen_node,
+ "linux,kexec-handover-buffer-end");
+ if (ret) {
+ pr_err("Error setting up the new device tree.\n");
+ return -EINVAL;
+ }
+ }
+ }
+
+ if (image->arch.handover_buffer_addr == 0)
+ return 0;
+
+ ret = fdt_setprop_u64(fdt, chosen_node,
+ "linux,kexec-handover-buffer-start",
+ image->arch.handover_buffer_addr);
+ if (ret < 0)
+ return -EINVAL;
+
+ /* -end is the first address after the buffer. */
+ ret = fdt_setprop_u64(fdt, chosen_node,
+ "linux,kexec-handover-buffer-end",
+ image->arch.handover_buffer_addr +
+ image->arch.handover_buffer_size);
+ if (ret < 0)
+ return -EINVAL;
+
+ ret = fdt_add_mem_rsv(fdt, image->arch.handover_buffer_addr,
+ image->arch.handover_buffer_size);
+ if (ret)
+ return -EINVAL;
+
+ pr_debug("kexec handover buffer at 0x%llx, size = 0x%lx\n",
+ image->arch.handover_buffer_addr,
+ image->arch.handover_buffer_size);
+
+ return 0;
+}
+
+/**
+ * setup_new_fdt() - modify /chosen and memory reservations for the next kernel
+ * @image: kexec image being loaded.
+ * @fdt: Flattened device tree for the next kernel.
+ * @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(const struct kimage *image, void *fdt,
+ unsigned long initrd_load_addr, unsigned long initrd_len,
+ const char *cmdline)
+{
+ int ret, chosen_node;
+ const void *prop;
+
+ /* Remove memory reservation for the current device tree. */
+ ret = delete_fdt_mem_rsv(fdt, __pa(initial_boot_params),
+ fdt_totalsize(initial_boot_params));
+ if (ret == 0)
+ pr_debug("Removed old device tree reservation.\n");
+ else if (ret != -ENOENT)
+ return ret;
+
chosen_node = fdt_path_offset(fdt, "/chosen");
if (chosen_node == -FDT_ERR_NOTFOUND) {
chosen_node = fdt_add_subnode(fdt, fdt_path_offset(fdt, "/"),
@@ -743,7 +937,7 @@ int setup_new_fdt(void *fdt, unsigned long initrd_load_addr,
/* 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;
+ uint64_t tmp_start, tmp_end, tmp_size;
tmp_start = fdt64_to_cpu(*((const fdt64_t *) prop));
@@ -759,30 +953,14 @@ int setup_new_fdt(void *fdt, unsigned long initrd_load_addr,
* 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;
- }
- }
+ ret = delete_fdt_mem_rsv(fdt, tmp_start, tmp_size);
+ if (ret == -ENOENT)
+ ret = delete_fdt_mem_rsv(fdt, tmp_start,
+ round_up(tmp_size, PAGE_SIZE));
+ if (ret == 0)
+ pr_debug("Removed old initrd reservation.\n");
+ else if (ret != -ENOENT)
+ return ret;
/* If there's no new initrd, delete the old initrd's info. */
if (initrd_len == 0) {
@@ -840,6 +1018,12 @@ int setup_new_fdt(void *fdt, unsigned long initrd_load_addr,
}
}
+ ret = setup_handover_buffer(image, fdt, chosen_node);
+ if (ret) {
+ pr_err("Error setting up the new device tree.\n");
+ return ret;
+ }
+
ret = fdt_setprop(fdt, chosen_node, "linux,booted-from-kexec", NULL, 0);
if (ret) {
pr_err("Error setting up the new device tree.\n");
--
1.9.1
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