[PATCH v4 1/9] kexec_file: Allow arch-specific memory walking for kexec_add_buffer

Thiago Jung Bauermann
2016-07-07T18:34:50Z

Allow architectures to specify a different memory walking function for
kexec_add_buffer. x86 uses iomem to track reserved memory ranges, but
PowerPC uses the memblock subsystem.

Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Dave Young <dyoung@redhat.com>
---
include/linux/kexec.h | 29 ++++++++++++++++++++++++++++-
kernel/kexec_file.c | 30 ++++++++++++++++++++++--------
kernel/kexec_internal.h | 16 ----------------
3 files changed, 50 insertions(+), 25 deletions(-)

diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index e8acb2b43dd9..2549a99a748c 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -146,7 +146,34 @@ struct kexec_file_ops {
kexec_verify_sig_t *verify_sig;
#endif
};
-#endif
+
+/**
+ * struct kexec_buf - parameters for finding a place for a buffer in memory
+ * @image: kexec image in which memory to search.
+ * @buffer: Contents which will be copied to the allocated memory.
+ * @bufsz: Size of @buffer.
+ * @mem: On return will have address of the buffer in memory.
+ * @memsz: Size for the buffer in memory.
+ * @buf_align: Minimum alignment needed.
+ * @buf_min: The buffer can't be placed below this address.
+ * @buf_max: The buffer can't be placed above this address.
+ * @top_down: Allocate from top of memory.
+ */
+struct kexec_buf {
+ struct kimage *image;
+ char *buffer;
+ unsigned long bufsz;
+ unsigned long mem;
+ unsigned long memsz;
+ unsigned long buf_align;
+ unsigned long buf_min;
+ unsigned long buf_max;
+ bool top_down;
+};
+
+int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
+ int (*func)(u64, u64, void *));
+#endif /* CONFIG_KEXEC_FILE */

struct kimage {
kimage_entry_t head;
diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index 01ab82a40d22..9c0c565a08db 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -428,6 +428,27 @@ static int locate_mem_hole_callback(u64 start, u64 end, void *arg)
return locate_mem_hole_bottom_up(start, end, kbuf);
}

+/**
+ * arch_kexec_walk_mem - call func(data) on free memory regions
+ * @kbuf: Context info for the search. Also passed to @func.
+ * @func: Function to call for each memory region.
+ *
+ * Return: The memory walk will stop when func returns a non-zero value
+ * and that value will be returned. If all free regions are visited without
+ * func returning non-zero, then zero will be returned.
+ */
+int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
+ int (*func)(u64, u64, void *))
+{
+ if (kbuf->image->type == KEXEC_TYPE_CRASH)
+ return walk_iomem_res_desc(crashk_res.desc,
+ IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY,
+ crashk_res.start, crashk_res.end,
+ kbuf, func);
+ else
+ return walk_system_ram_res(0, ULONG_MAX, kbuf, func);
+}
+
/*
* Helper function for placing a buffer in a kexec segment. This assumes
* that kexec_mutex is held.
@@ -474,14 +495,7 @@ int kexec_add_buffer(struct kimage *image, char *buffer, unsigned long bufsz,
kbuf->top_down = top_down;

/* Walk the RAM ranges and allocate a suitable range for the buffer */
- if (image->type == KEXEC_TYPE_CRASH)
- ret = walk_iomem_res_desc(crashk_res.desc,
- IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY,
- crashk_res.start, crashk_res.end, kbuf,
- locate_mem_hole_callback);
- else
- ret = walk_system_ram_res(0, -1, kbuf,
- locate_mem_hole_callback);
+ ret = arch_kexec_walk_mem(kbuf, locate_mem_hole_callback);
if (ret != 1) {
/* A suitable memory range could not be found for buffer */
return -EADDRNOTAVAIL;
diff --git a/kernel/kexec_internal.h b/kernel/kexec_internal.h
index 0a52315d9c62..4cef7e4706b0 100644
--- a/kernel/kexec_internal.h
+++ b/kernel/kexec_internal.h
@@ -20,22 +20,6 @@ struct kexec_sha_region {
unsigned long len;
};

-/*
- * Keeps track of buffer parameters as provided by caller for requesting
- * memory placement of buffer.
- */
-struct kexec_buf {
- struct kimage *image;
- char *buffer;
- unsigned long bufsz;
- unsigned long mem;
- unsigned long memsz;
- unsigned long buf_align;
- unsigned long buf_min;
- unsigned long buf_max;
- bool top_down; /* allocate from top of memory hole */
-};
-
void kimage_file_post_load_cleanup(struct kimage *image);
#else /* CONFIG_KEXEC_FILE */
static inline void kimage_file_post_load_cleanup(struct kimage *image) { }
--
1.9.1