linux-kernel - [PATCH v8 4/7] extable: Add function to search only kernel exception table

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Message-Id: <20190807145700.25599-5-santosh@fossix.org>
Date:   Wed,  7 Aug 2019 20:26:57 +0530
From:   Santosh Sivaraj <santosh@...six.org>
To:     linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        Linux Kernel <linux-kernel@...r.kernel.org>
Cc:     "Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>,
        Mahesh Salgaonkar <mahesh@...ux.ibm.com>,
        Reza Arbab <arbab@...ux.ibm.com>,
        Balbir Singh <bsingharora@...il.com>,
        Chandan Rajendra <chandan@...ux.vnet.ibm.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Nicholas Piggin <npiggin@...il.com>,
        christophe leroy <christophe.leroy@....fr>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>
Subject: [PATCH v8 4/7] extable: Add function to search only kernel exception table

Certain architecture specific operating modes (e.g., in powerpc machine
check handler that is unable to access vmalloc memory), the
search_exception_tables cannot be called because it also searches the
module exception tables if entry is not found in the kernel exception
table.

Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Nicholas Piggin <npiggin@...il.com>
Signed-off-by: Santosh Sivaraj <santosh@...six.org>
Reviewed-by: Nicholas Piggin <npiggin@...il.com>
---
 include/linux/extable.h |  2 ++
 kernel/extable.c        | 11 +++++++++--
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/include/linux/extable.h b/include/linux/extable.h
index 41c5b3a25f67..81ecfaa83ad3 100644
--- a/include/linux/extable.h
+++ b/include/linux/extable.h
@@ -19,6 +19,8 @@ void trim_init_extable(struct module *m);
 
 /* Given an address, look for it in the exception tables */
 const struct exception_table_entry *search_exception_tables(unsigned long add);
+const struct exception_table_entry *
+search_kernel_exception_table(unsigned long addr);
 
 #ifdef CONFIG_MODULES
 /* For extable.c to search modules' exception tables. */
diff --git a/kernel/extable.c b/kernel/extable.c
index e23cce6e6092..f6c9406eec7d 100644
--- a/kernel/extable.c
+++ b/kernel/extable.c
@@ -40,13 +40,20 @@ void __init sort_main_extable(void)
 	}
 }
 
+/* Given an address, look for it in the kernel exception table */
+const
+struct exception_table_entry *search_kernel_exception_table(unsigned long addr)
+{
+	return search_extable(__start___ex_table,
+			      __stop___ex_table - __start___ex_table, addr);
+}
+
 /* Given an address, look for it in the exception tables. */
 const struct exception_table_entry *search_exception_tables(unsigned long addr)
 {
 	const struct exception_table_entry *e;
 
-	e = search_extable(__start___ex_table,
-			   __stop___ex_table - __start___ex_table, addr);
+	e = search_kernel_exception_table(addr);
 	if (!e)
 		e = search_module_extables(addr);
 	return e;
-- 
2.20.1