crash: let arch decide usable memory range in reserved area

Although the crashkernel area is reserved, on architectures like PowerPC,
it is possible for the crashkernel reserved area to contain components
like RTAS, TCE, OPAL, etc.  To avoid placing kexec segments over these
components, PowerPC has its own set of APIs to locate holes in the
crashkernel reserved area.

Add an arch hook in the generic locate mem hole APIs so that architectures
can handle such special regions in the crashkernel area while locating
memory holes for kexec segments using generic APIs.  With this, a lot of
redundant arch-specific code can be removed, as it performs the exact same
job as the generic APIs.

To keep the generic and arch-specific changes separate, the changes
related to moving PowerPC to use the generic APIs and the removal of
PowerPC-specific APIs for memory hole allocation are done in a subsequent
patch titled "powerpc/crash: Use generic APIs to locate memory hole for
kdump.

Link: https://lkml.kernel.org/r/20250131113830.925179-4-sourabhjain@linux.ibm.com
Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Hari Bathini <hbathini@linux.ibm.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mahesh Salgaonkar <mahesh@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index f0e9f8eda7a3c022b87d579391861b463bce14d0..407f8b0346aa098499528bef6e3d65e1a271eebb 100644 (file)
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -205,6 +205,15 @@ static inline int arch_kimage_file_post_load_cleanup(struct kimage *image)
 }
 #endif
 
+#ifndef arch_check_excluded_range
+static inline int arch_check_excluded_range(struct kimage *image,
+                                           unsigned long start,
+                                           unsigned long end)
+{
+       return 0;
+}
+#endif
+
 #ifdef CONFIG_KEXEC_SIG
 #ifdef CONFIG_SIGNED_PE_FILE_VERIFICATION
 int kexec_kernel_verify_pe_sig(const char *kernel, unsigned long kernel_len);

diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index 3eedb8c226ad8f6a7cfad127dbe12019394d126e..fba686487e3b511675da0206c65ed2c0a9c65aff 100644 (file)
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -464,6 +464,12 @@ static int locate_mem_hole_top_down(unsigned long start, unsigned long end,
                        continue;
                }
 
+               /* Make sure this does not conflict with exclude range */
+               if (arch_check_excluded_range(image, temp_start, temp_end)) {
+                       temp_start = temp_start - PAGE_SIZE;
+                       continue;
+               }
+
                /* We found a suitable memory range */
                break;
        } while (1);
@@ -498,6 +504,12 @@ static int locate_mem_hole_bottom_up(unsigned long start, unsigned long end,
                        continue;
                }
 
+               /* Make sure this does not conflict with exclude range */
+               if (arch_check_excluded_range(image, temp_start, temp_end)) {
+                       temp_start = temp_start + PAGE_SIZE;
+                       continue;
+               }
+
                /* We found a suitable memory range */
                break;
        } while (1);