linux-kernel - [PATCH] ARM: Add ".text.unlikely" and ".text.hot" to arm unwind tables

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Date:	Tue,  6 Aug 2013 14:41:15 -0700
From:	Doug Anderson <dianders@...omium.org>
To:	linux-arm-kernel@...ts.infradead.org
Cc:	Olof Johansson <olof@...om.net>,
	Mike Frysinger <vapier@...too.org>,
	Sonny Rao <sonnyrao@...omium.org>,
	Doug Anderson <dianders@...omium.org>,
	Russell King <linux@....linux.org.uk>,
	Rusty Russell <rusty@...tcorp.com.au>,
	David Howells <dhowells@...hat.com>,
	Sam Ravnborg <sam@...nborg.org>,
	Stephen Rothwell <sfr@...b.auug.org.au>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Mauro Carvalho Chehab <mchehab@...hat.com>,
	Hans Verkuil <hans.verkuil@...co.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH] ARM: Add ".text.unlikely" and ".text.hot" to arm unwind tables

It appears that gcc may put some code in ".text.unlikely" or
".text.hot" sections.  Right now those aren't accounted for in unwind
tables.  Add them.

I found some docs about this at:
  http://gcc.gnu.org/onlinedocs/gcc-4.6.2/gcc.pdf

Without this, if you have slub_debug turned on, you can get messages
that look like this:
  unwind: Index not found 7f008c50

Signed-off-by: Doug Anderson <dianders@...omium.org>
---
 arch/arm/include/asm/module.h | 2 ++
 arch/arm/kernel/module.c      | 8 ++++++++
 2 files changed, 10 insertions(+)

diff --git a/arch/arm/include/asm/module.h b/arch/arm/include/asm/module.h
index 0d3a28d..ed690c4 100644
--- a/arch/arm/include/asm/module.h
+++ b/arch/arm/include/asm/module.h
@@ -12,6 +12,8 @@ enum {
 	ARM_SEC_CORE,
 	ARM_SEC_EXIT,
 	ARM_SEC_DEVEXIT,
+	ARM_SEC_HOT,
+	ARM_SEC_UNLIKELY,
 	ARM_SEC_MAX,
 };
 
diff --git a/arch/arm/kernel/module.c b/arch/arm/kernel/module.c
index 85c3fb6..084dc88 100644
--- a/arch/arm/kernel/module.c
+++ b/arch/arm/kernel/module.c
@@ -292,12 +292,20 @@ int module_finalize(const Elf32_Ehdr *hdr, const Elf_Shdr *sechdrs,
 			maps[ARM_SEC_CORE].unw_sec = s;
 		else if (strcmp(".ARM.exidx.exit.text", secname) == 0)
 			maps[ARM_SEC_EXIT].unw_sec = s;
+		else if (strcmp(".ARM.exidx.text.unlikely", secname) == 0)
+			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(".init.text", secname) == 0)
 			maps[ARM_SEC_INIT].txt_sec = s;
 		else if (strcmp(".text", secname) == 0)
 			maps[ARM_SEC_CORE].txt_sec = s;
 		else if (strcmp(".exit.text", secname) == 0)
 			maps[ARM_SEC_EXIT].txt_sec = s;
+		else if (strcmp(".text.unlikely", secname) == 0)
+			maps[ARM_SEC_UNLIKELY].txt_sec = s;
+		else if (strcmp(".text.hot", secname) == 0)
+			maps[ARM_SEC_HOT].txt_sec = s;
 	}
 
 	for (i = 0; i < ARM_SEC_MAX; i++)
-- 
1.8.3

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