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-independent part of the feature.
Signed-off-by: Thiago Jung Bauermann <bauerman at linux.vnet.ibm.com>
---
include/linux/kexec.h | 40 ++++++++++++++++++++++++++
kernel/kexec_file.c | 79 +++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 119 insertions(+)
diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index a08cd986b5a1..72db95c623b3 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -325,6 +325,46 @@ int __weak arch_kexec_walk_mem(unsigned int image_type, unsigned long start,
void arch_kexec_protect_crashkres(void);
void arch_kexec_unprotect_crashkres(void);
+#ifdef CONFIG_KEXEC_FILE
+bool __weak kexec_can_hand_over_buffer(void);
+int __weak arch_kexec_add_handover_buffer(struct kimage *image,
+ unsigned long load_addr,
+ unsigned long size);
+int kexec_add_handover_buffer(struct kimage *image, void *buffer,
+ unsigned long bufsz, unsigned long memsz,
+ unsigned long buf_align, unsigned long buf_min,
+ unsigned long buf_max, bool top_down,
+ unsigned long *load_addr);
+int __weak kexec_get_handover_buffer(void **addr, unsigned long *size);
+int __weak kexec_free_handover_buffer(void);
+#else
+static inline bool kexec_can_hand_over_buffer(void)
+{
+ return false;
+}
+
+static inline int kexec_add_handover_buffer(struct kimage *image, void *buffer,
+ unsigned long bufsz,
+ unsigned long memsz,
+ unsigned long buf_align,
+ unsigned long buf_min,
+ unsigned long buf_max,
+ bool top_down, bool checksum,
+ unsigned long *load_addr)
+{
+ return -ENOTSUPP;
+}
+
+static inline int kexec_get_handover_buffer(void **addr, unsigned long *size)
+{
+ return -ENOTSUPP;
+}
+
+static inline int kexec_free_handover_buffer(void)
+{
+ return -ENOTSUPP;
+}
+#endif /* CONFIG_KEXEC_FILE */
#else /* !CONFIG_KEXEC_CORE */
struct pt_regs;
struct task_struct;
diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index 3e494261d32a..d6ba702654f5 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -113,6 +113,85 @@ void kimage_file_post_load_cleanup(struct kimage *image)
image->image_loader_data = NULL;
}
+/**
+ * kexec_can_hand_over_buffer - can we pass data to the kexec'd kernel?
+ */
+bool __weak kexec_can_hand_over_buffer(void)
+{
+ return false;
+}
+
+/**
+ * arch_kexec_add_handover_buffer - do arch-specific steps to handover buffer
+ *
+ * Architectures should use this function to pass on the handover buffer
+ * information to the next kernel.
+ *
+ * Return: 0 on success, negative errno on error.
+ */
+int __weak arch_kexec_add_handover_buffer(struct kimage *image,
+ unsigned long load_addr,
+ unsigned long size)
+{
+ return -ENOTSUPP;
+}
+
+/**
+ * kexec_add_handover_buffer - add buffer to be used by the next kernel
+ * @image: kexec image to add buffer to.
+ * @buffer: Contents of the handover buffer.
+ * @bufsz: @buffer size.
+ * @memsz: Handover buffer size in memory.
+ * @buf_align: Buffer alignment restriction.
+ * @buf_min: Minimum address where buffer can be placed.
+ * @buf_max: Maximum address where buffer can be placed.
+ * @top_down: Find the highest available memory position for the buffer?
+ * @load_addr: On successful return, set to the physical memory address of the
+ * buffer in the next kernel.
+ *
+ * This function assumes that kexec_mutex is held.
+ *
+ * Return: 0 on success, negative errno on error.
+ */
+int kexec_add_handover_buffer(struct kimage *image, void *buffer,
+ unsigned long bufsz, unsigned long memsz,
+ unsigned long buf_align, unsigned long buf_min,
+ unsigned long buf_max, bool top_down,
+ unsigned long *load_addr)
+{
+ int ret;
+
+ if (!kexec_can_hand_over_buffer())
+ return -ENOTSUPP;
+
+ ret = kexec_add_buffer(image, buffer, bufsz, memsz, buf_align, buf_min,
+ buf_max, top_down, load_addr);
+ if (ret)
+ return ret;
+
+ return arch_kexec_add_handover_buffer(image, *load_addr, memsz);
+}
+
+/**
+ * kexec_get_handover_buffer - get the handover buffer from the previous kernel
+ * @addr: On successful return, set to point to the buffer contents.
+ * @size: On successful return, set to the buffer size.
+ *
+ * Return: 0 on success, negative errno on error.
+ */
+int __weak kexec_get_handover_buffer(void **addr, unsigned long *size)
+{
+ return -ENOTSUPP;
+}
+
+/**
+ * kexec_free_handover_buffer - free memory used by the handover buffer
+ */
+int __weak kexec_free_handover_buffer(void)
+{
+ return -ENOTSUPP;
+}
+
/*
* In file mode list of segments is prepared by kernel. Copy relevant
* data from user space, do error checking, prepare segment list
--
1.9.1
