From: Palmer Dabbelt <palmerdabb...@google.com>
A version of this that is identical to the arm64 version was recently
copied into the RISC-V port while adding kexec() support. Instead I'd
like to put a shared copy in lib/ and use it from the various ports.
Signed-off-by: Palmer Dabbelt <palmerdabb...@google.com>
---
lib/Kconfig | 3 +++
lib/Makefile | 2 ++
lib/copy_oldmem_page.c | 51 ++++++++++++++++++++++++++++++++++++++++++
3 files changed, 56 insertions(+)
create mode 100644 lib/copy_oldmem_page.c
diff --git a/lib/Kconfig b/lib/Kconfig
index df3f3da95990..25544abc9547 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -676,3 +676,6 @@ config GENERIC_LIB_CMPDI2
config GENERIC_LIB_UCMPDI2
bool
+
+config GENERIC_LIB_COPY_OLDMEM_PAGE
+ bool
diff --git a/lib/Makefile b/lib/Makefile
index b1c42c10073b..30d57d8b32b1 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -318,3 +318,5 @@ obj-$(CONFIG_OBJAGG) += objagg.o
# KUnit tests
obj-$(CONFIG_LIST_KUNIT_TEST) += list-test.o
obj-$(CONFIG_LINEAR_RANGES_TEST) += test_linear_ranges.o
+
+obj-$(CONFIG_GENERIC_LIB_COPY_OLDMEM_PAGE) += copy_oldmem_page.o
diff --git a/lib/copy_oldmem_page.c b/lib/copy_oldmem_page.c
new file mode 100644
index 000000000000..f0090027218a
--- /dev/null
+++ b/lib/copy_oldmem_page.c
@@ -0,0 +1,51 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Routines for doing kexec-based kdump
+ *
+ * Originally part of arch/arm64/kernel/crash_dump.c
+ * Copyright (C) 2017 Linaro Limited
+ * Author: AKASHI Takahiro <takahiro.aka...@linaro.org>
+ */
+
+#include <linux/io.h>
+#include <linux/types.h>
+#include <linux/uaccess.h>
+
+/**
+ * copy_oldmem_page() - copy one page from old kernel memory
+ * @pfn: page frame number to be copied
+ * @buf: buffer where the copied page is placed
+ * @csize: number of bytes to copy
+ * @offset: offset in bytes into the page
+ * @userbuf: if set, @buf is in a user address space
+ *
+ * This function copies one page from old kernel memory into buffer pointed by
+ * @buf. If @buf is in userspace, set @userbuf to %1. Returns number of bytes
+ * copied or negative error in case of failure.
+ */
+ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
+ size_t csize, unsigned long offset,
+ int userbuf)
+{
+ void *vaddr;
+
+ if (!csize)
+ return 0;
+
+ vaddr = memremap(__pfn_to_phys(pfn), PAGE_SIZE, MEMREMAP_WB);
+ if (!vaddr)
+ return -ENOMEM;
+
+ if (userbuf) {
+ if (copy_to_user((char __user *)buf, vaddr + offset, csize)) {
+ memunmap(vaddr);
+ return -EFAULT;
+ }
+ } else {
+ memcpy(buf, vaddr + offset, csize);
+ }
+
+ memunmap(vaddr);
+
+ return csize;
+}
--
2.27.0.383.g050319c2ae-goog
