linux-kernel - [PATCH v2 3/3] powerpc/fadump: make is_kdump_kernel() return false when fadump is active

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Message-ID: <20230905183604.568996-3-hbathini@linux.ibm.com>
Date:   Wed,  6 Sep 2023 00:06:04 +0530
From:   Hari Bathini <hbathini@...ux.ibm.com>
To:     lkml <linux-kernel@...r.kernel.org>,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        Kexec-ml <kexec@...ts.infradead.org>
Cc:     Dave Young <dyoung@...hat.com>, Baoquan He <bhe@...hat.com>,
        Mahesh J Salgaonkar <mahesh@...ux.ibm.com>,
        Sourabh Jain <sourabhjain@...ux.ibm.com>,
        Michael Ellerman <mpe@...erman.id.au>
Subject: [PATCH v2 3/3] 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@...ux.ibm.com>
---
 arch/powerpc/include/asm/kexec.h |  2 ++
 arch/powerpc/kernel/crash_dump.c | 11 +++++++++++
 2 files changed, 13 insertions(+)

diff --git a/arch/powerpc/include/asm/kexec.h b/arch/powerpc/include/asm/kexec.h
index b760ef459234..f0b9c3fd0618 100644
--- a/arch/powerpc/include/asm/kexec.h
+++ b/arch/powerpc/include/asm/kexec.h
@@ -101,6 +101,8 @@ void relocate_new_kernel(unsigned long indirection_page, unsigned long reboot_co
 void kexec_copy_flush(struct kimage *image);
 
 #if defined(CONFIG_CRASH_DUMP)
+bool is_kdump_kernel(void);
+#define is_kdump_kernel			is_kdump_kernel
 #define is_fadump_active		is_fadump_active
 #if defined(CONFIG_PPC_RTAS)
 void crash_free_reserved_phys_range(unsigned long begin, unsigned long end);
diff --git a/arch/powerpc/kernel/crash_dump.c b/arch/powerpc/kernel/crash_dump.c
index 9a3b85bfc83f..6d8e616ce3ce 100644
--- a/arch/powerpc/kernel/crash_dump.c
+++ b/arch/powerpc/kernel/crash_dump.c
@@ -92,6 +92,17 @@ 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
-- 
2.41.0