powerpc/fadump: make is_kdump_kernel() return false when fadump is active

Currently, is_kdump_kernel() returns true in crash dump capture kernel
for both kdump and fadump crash dump capturing methods, as both these
methods set elfcorehdr_addr. Some restrictions enforced for crash dump
capture kernel, based on is_kdump_kernel(), are specifically meant for
kdump case and not desirable for fadump - eg. IO queues restriction in
device drivers. So, define is_kdump_kernel() to return false when f/w
assisted dump is active.
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Acked-by: Baoquan He <bhe@redhat.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230912082950.856977-2-hbathini@linux.ibm.com

arch/powerpc/include/asm/kexec.h

@@ -99,10 +99,14 @@ void relocate_new_kernel(unsigned long indirection_page, unsigned long reboot_co
 
 void kexec_copy_flush(struct kimage *image);
 
-#if defined(CONFIG_CRASH_DUMP) && defined(CONFIG_PPC_RTAS)
+#if defined(CONFIG_CRASH_DUMP)
+bool is_kdump_kernel(void);
+#define is_kdump_kernel			is_kdump_kernel
+#if defined(CONFIG_PPC_RTAS)
 void crash_free_reserved_phys_range(unsigned long begin, unsigned long end);
 #define crash_free_reserved_phys_range crash_free_reserved_phys_range
-#endif
+#endif /* CONFIG_PPC_RTAS */
+#endif /* CONFIG_CRASH_DUMP */
 
 #ifdef CONFIG_KEXEC_FILE
 extern const struct kexec_file_ops kexec_elf64_ops;

arch/powerpc/kernel/crash_dump.c

@@ -19,6 +19,7 @@
 #include <linux/uio.h>
 #include <asm/rtas.h>
 #include <asm/inst.h>
+#include <asm/fadump.h>
 
 #ifdef DEBUG
 #include <asm/udbg.h>
@@ -92,6 +93,17 @@ ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn,
 	return csize;
 }
 
+/*
+ * Return true only when kexec based kernel dump capturing method is used.
+ * This ensures all restritions applied for kdump case are not automatically
+ * applied for fadump case.
+ */
+bool is_kdump_kernel(void)
+{
+	return !is_fadump_active() && elfcorehdr_addr != ELFCORE_ADDR_MAX;
+}
+EXPORT_SYMBOL_GPL(is_kdump_kernel);
+
 #ifdef CONFIG_PPC_RTAS
 /*
  * The crashkernel region will almost always overlap the RTAS region, so