linux-kernel - [PATCH v2 01/12] kexec_file: allow archs to handle special regions while locating memory hole

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Message-ID: <159371964681.21555.573193508667543223.stgit@hbathini.in.ibm.com>
Date:   Fri, 03 Jul 2020 01:24:13 +0530
From:   Hari Bathini <hbathini@...ux.ibm.com>
To:     Michael Ellerman <mpe@...erman.id.au>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     kernel test robot <lkp@...el.com>, Pingfan Liu <piliu@...hat.com>,
        Kexec-ml <kexec@...ts.infradead.org>,
        Mimi Zohar <zohar@...ux.ibm.com>,
        Petr Tesarik <ptesarik@...e.cz>,
        Mahesh J Salgaonkar <mahesh@...ux.ibm.com>,
        Sourabh Jain <sourabhjain@...ux.ibm.com>,
        lkml <linux-kernel@...r.kernel.org>,
        linuxppc-dev <linuxppc-dev@...abs.org>,
        Eric Biederman <ebiederm@...ssion.com>,
        Thiago Jung Bauermann <bauerman@...ux.ibm.com>,
        Dave Young <dyoung@...hat.com>, Vivek Goyal <vgoyal@...hat.com>
Subject: [PATCH v2 01/12] kexec_file: allow archs to handle special regions
 while locating memory hole

Some architectures may have special memory regions, within the given
memory range, which can't be used for the buffer in a kexec segment.
Implement weak arch_kexec_locate_mem_hole() definition which arch code
may override, to take care of special regions, while trying to locate
a memory hole.

Also, add the missing declarations for arch overridable functions and
and drop the __weak descriptors in the declarations to avoid non-weak
definitions from becoming weak.

Reported-by: kernel test robot <lkp@...el.com>
[lkp: In v1, arch_kimage_file_post_load_cleanup() declaration was missing]
Signed-off-by: Hari Bathini <hbathini@...ux.ibm.com>
---

Changes in v2:
* Introduced arch_kexec_locate_mem_hole() for override and dropped
  weak arch_kexec_add_buffer().
* Dropped __weak identifier for arch overridable functions.
* Fixed the missing declaration for arch_kimage_file_post_load_cleanup()
  reported by lkp. lkp report for reference:
    - https://lore.kernel.org/patchwork/patch/1264418/


 include/linux/kexec.h |   29 ++++++++++++++++++-----------
 kernel/kexec_file.c   |   16 ++++++++++++++--
 2 files changed, 32 insertions(+), 13 deletions(-)

diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index ea67910..9e93bef 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -183,17 +183,24 @@ int kexec_purgatory_get_set_symbol(struct kimage *image, const char *name,
 				   bool get_value);
 void *kexec_purgatory_get_symbol_addr(struct kimage *image, const char *name);
 
-int __weak arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
-					 unsigned long buf_len);
-void * __weak arch_kexec_kernel_image_load(struct kimage *image);
-int __weak arch_kexec_apply_relocations_add(struct purgatory_info *pi,
-					    Elf_Shdr *section,
-					    const Elf_Shdr *relsec,
-					    const Elf_Shdr *symtab);
-int __weak arch_kexec_apply_relocations(struct purgatory_info *pi,
-					Elf_Shdr *section,
-					const Elf_Shdr *relsec,
-					const Elf_Shdr *symtab);
+/* Architectures may override the below functions */
+int arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
+				  unsigned long buf_len);
+void *arch_kexec_kernel_image_load(struct kimage *image);
+int arch_kexec_apply_relocations_add(struct purgatory_info *pi,
+				     Elf_Shdr *section,
+				     const Elf_Shdr *relsec,
+				     const Elf_Shdr *symtab);
+int arch_kexec_apply_relocations(struct purgatory_info *pi,
+				 Elf_Shdr *section,
+				 const Elf_Shdr *relsec,
+				 const Elf_Shdr *symtab);
+int arch_kimage_file_post_load_cleanup(struct kimage *image);
+#ifdef CONFIG_KEXEC_SIG
+int arch_kexec_kernel_verify_sig(struct kimage *image, void *buf,
+				 unsigned long buf_len);
+#endif
+int arch_kexec_locate_mem_hole(struct kexec_buf *kbuf);
 
 extern int kexec_add_buffer(struct kexec_buf *kbuf);
 int kexec_locate_mem_hole(struct kexec_buf *kbuf);
diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index 09cc78d..e89912d 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -636,6 +636,19 @@ int kexec_locate_mem_hole(struct kexec_buf *kbuf)
 }
 
 /**
+ * arch_kexec_locate_mem_hole - Find free memory to place the segments.
+ * @kbuf:                       Parameters for the memory search.
+ *
+ * On success, kbuf->mem will have the start address of the memory region found.
+ *
+ * Return: 0 on success, negative errno on error.
+ */
+int __weak arch_kexec_locate_mem_hole(struct kexec_buf *kbuf)
+{
+	return kexec_locate_mem_hole(kbuf);
+}
+
+/**
  * kexec_add_buffer - place a buffer in a kexec segment
  * @kbuf:	Buffer contents and memory parameters.
  *
@@ -647,7 +660,6 @@ int kexec_locate_mem_hole(struct kexec_buf *kbuf)
  */
 int kexec_add_buffer(struct kexec_buf *kbuf)
 {
-
 	struct kexec_segment *ksegment;
 	int ret;
 
@@ -675,7 +687,7 @@ int kexec_add_buffer(struct kexec_buf *kbuf)
 	kbuf->buf_align = max(kbuf->buf_align, PAGE_SIZE);
 
 	/* Walk the RAM ranges and allocate a suitable range for the buffer */
-	ret = kexec_locate_mem_hole(kbuf);
+	ret = arch_kexec_locate_mem_hole(kbuf);
 	if (ret)
 		return ret;