[PATCH] ARM: module: Add ".ref.text" to arm unwind tables

Vignesh Radhakrishnan vigneshr at codeaurora.org
Fri Jun 19 02:35:52 PDT 2015

Functions inside kernel modules that use __ref
will end up being placed in .ARM.exidx.ref.text
section by gcc.

Currently we don't consider adding these functions
to arm unwind tables.

Hence, if we turn slub debug on by default we end up
with the messages of this sort:

unwind: Index not found bf0011e0

This is because slub debug saves stack trace of
allocation's and free's. Therefore, we end up seeing
a flood of these messages in dmesg since its not
able to locate these functions.

Fix this by adding .ref.text section to arm unwind tables.

Tested-by: Laura Abbott <labbott at redhat.com>
Signed-off-by: Vignesh Radhakrishnan <vigneshr at codeaurora.org>
CC: Russell King <linux at arm.linux.org.uk>
CC: Andrew Morton <akpm at linux-foundation.org>
CC: Laura Abbott <labbott at redhat.com>
CC: Andrey Ryabinin <a.ryabinin at samsung.com>
CC: Andrey Konovalov <adech.fo at gmail.com>
 arch/arm/include/asm/module.h | 1 +
 arch/arm/kernel/module.c      | 4 ++++
 2 files changed, 5 insertions(+)

diff --git a/arch/arm/include/asm/module.h b/arch/arm/include/asm/module.h
index ed690c4..17640c9 100644
--- a/arch/arm/include/asm/module.h
+++ b/arch/arm/include/asm/module.h
@@ -14,6 +14,7 @@ enum {
diff --git a/arch/arm/kernel/module.c b/arch/arm/kernel/module.c
index 2e11961..846b888 100644
--- a/arch/arm/kernel/module.c
+++ b/arch/arm/kernel/module.c
@@ -308,6 +308,8 @@ int module_finalize(const Elf32_Ehdr *hdr, const Elf_Shdr *sechdrs,
 			maps[ARM_SEC_UNLIKELY].unw_sec = s;
 		else if (strcmp(".ARM.exidx.text.hot", secname) == 0)
 			maps[ARM_SEC_HOT].unw_sec = s;
+		else if (strcmp(".ARM.exidx.ref.text", secname) == 0)
+			maps[ARM_SEC_REF].unw_sec = s;
 		else if (strcmp(".init.text", secname) == 0)
 			maps[ARM_SEC_INIT].txt_sec = s;
 		else if (strcmp(".text", secname) == 0)
@@ -318,6 +320,8 @@ int module_finalize(const Elf32_Ehdr *hdr, const Elf_Shdr *sechdrs,
 			maps[ARM_SEC_UNLIKELY].txt_sec = s;
 		else if (strcmp(".text.hot", secname) == 0)
 			maps[ARM_SEC_HOT].txt_sec = s;
+		else if (strcmp(".ref.text", secname) == 0)
+			maps[ARM_SEC_REF].txt_sec = s;
 	for (i = 0; i < ARM_SEC_MAX; i++)

Thanks and regards,
Vignesh Radhakrishnan

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