The patch titled
Subject: kexec_file: allow arch-specific memory walking for kexec_add_buffer
has been added to the -mm tree. Its filename is
kexec_file-allow-arch-specific-memory-walking-for-kexec_add_buffer.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/kexec_file-allow-arch-specific-memory-walking-for-kexec_add_buffer.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/kexec_file-allow-arch-specific-memory-walking-for-kexec_add_buffer.patch
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------------------------------------------------------
From: Thiago Jung Bauermann <bauerman@xxxxxxxxxxxxxxxxxx>
Subject: kexec_file: allow arch-specific memory walking for kexec_add_buffer
Patch series "kexec_file_load implementation for PowerPC", v10.
This patch series implements the kexec_file_load system call on PowerPC.
This system call moves the reading of the kernel, initrd and the device tree
from the userspace kexec tool to the kernel. This is needed if you want to
do one or both of the following:
1. only allow loading of signed kernels.
2. "measure" (i.e., record the hashes of) the kernel, initrd, kernel
command line and other boot inputs for the Integrity Measurement
Architecture subsystem.
The above are the functions kexec already has built into kexec_file_load.
Yesterday I posted a set of patches which allows a third feature:
3. have IMA pass-on its event log (where integrity measurements are
registered) accross kexec to the second kernel, so that the event
history is preserved.
Because OpenPower uses an intermediary Linux instance as a boot loader
(skiroot), feature 1 is needed to implement secure boot for the platform,
while features 2 and 3 are needed to implement trusted boot.
This patch series starts by removing an x86 assumption from kexec_file:
kexec_add_buffer uses iomem to find reserved memory ranges, but PowerPC
uses the memblock subsystem. A hook is added so that each arch can
specify how memory ranges can be found.
Also, the memory-walking logic in kexec_add_buffer is useful in this
implementation to find a free area for the purgatory's stack, so the
next patch moves that logic to kexec_locate_mem_hole.
The kexec_file_load system call needs to apply relocations to the
purgatory but adding code for that would duplicate functionality with
the module loading mechanism, which also needs to apply relocations to
the kernel modules. Therefore, this patch series factors out the module
relocation code so that it can be shared.
One thing that is still missing is crashkernel support, which I intend
to submit shortly. For now, arch_kexec_kernel_image_probe rejects crash
kernels.
This code is based on kexec-tools, but with many modifications to adapt
it to the kernel environment and facilities. Except the purgatory,
which only has minimal changes.
This patch (of 10):
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.
Link: http://lkml.kernel.org/r/1478748449-3894-2-git-send-email-bauerman@xxxxxxxxxxxxxxxxxx
Signed-off-by: Thiago Jung Bauermann <bauerman@xxxxxxxxxxxxxxxxxx>
Acked-by: Dave Young <dyoung@xxxxxxxxxx>
Acked-by: Balbir Singh <bsingharora@xxxxxxxxx>
Cc: Josh Sklar <sklar@xxxxxxxxxxxxxxxxxx>
Cc: Eric Biederman <ebiederm@xxxxxxxxxxxx>
Cc: Dave Young <dyoung@xxxxxxxxxx>
Cc: Vivek Goyal <vgoyal@xxxxxxxxxx>
Cc: Baoquan He <bhe@xxxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Stewart Smith <stewart@xxxxxxxxxxxxxxxxxx>
Cc: Mimi Zohar <zohar@xxxxxxxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/kexec.h | 29 ++++++++++++++++++++++++++++-
kernel/kexec_file.c | 30 ++++++++++++++++++++++--------
kernel/kexec_internal.h | 16 ----------------
3 files changed, 50 insertions(+), 25 deletions(-)
diff -puN include/linux/kexec.h~kexec_file-allow-arch-specific-memory-walking-for-kexec_add_buffer include/linux/kexec.h
--- a/include/linux/kexec.h~kexec_file-allow-arch-specific-memory-walking-for-kexec_add_buffer
+++ a/include/linux/kexec.h
@@ -148,7 +148,34 @@ 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 -puN kernel/kexec_file.c~kexec_file-allow-arch-specific-memory-walking-for-kexec_add_buffer kernel/kexec_file.c
--- a/kernel/kexec_file.c~kexec_file-allow-arch-specific-memory-walking-for-kexec_add_buffer
+++ a/kernel/kexec_file.c
@@ -428,6 +428,27 @@ static int locate_mem_hole_callback(u64
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 *imag
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 -puN kernel/kexec_internal.h~kexec_file-allow-arch-specific-memory-walking-for-kexec_add_buffer kernel/kexec_internal.h
--- a/kernel/kexec_internal.h~kexec_file-allow-arch-specific-memory-walking-for-kexec_add_buffer
+++ a/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) { }
_
Patches currently in -mm which might be from bauerman@xxxxxxxxxxxxxxxxxx are
kexec_file-allow-arch-specific-memory-walking-for-kexec_add_buffer.patch
kexec_file-change-kexec_add_buffer-to-take-kexec_buf-as-argument.patch
kexec_file-factor-out-kexec_locate_mem_hole-from-kexec_add_buffer.patch
kexec_file-add-support-for-purgatory-built-as-pie.patch
powerpc-change-places-using-config_kexec-to-use-config_kexec_core-instead.patch
powerpc-implement-kexec_file_load.patch
powerpc-add-functions-to-read-elf-files-of-any-endianness.patch
powerpc-add-support-for-loading-elf-kernels-with-kexec_file_load.patch
powerpc-add-purgatory-for-kexec_file_load-implementation.patch
powerpc-enable-config_kexec_file-in-powerpc-server-defconfigs.patch
powerpc-ima-get-the-kexec-buffer-passed-by-the-previous-kernel.patch
powerpc-ima-send-the-kexec-buffer-to-the-next-kernel.patch
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