linux-kernel - [PATCH v3 4/7] tile: support static_key usage in non-module _

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Message-Id: <bfd7c107c610c30e992868ebfe2a5d796a097464.1467837322.git.jbaron@akamai.com>
Date:	Wed,  6 Jul 2016 17:42:33 -0400
From:	Jason Baron <jbaron@...mai.com>
To:	akpm@...ux-foundation.org
Cc:	joe@...ches.com, peterz@...radead.org,
	linux-kernel@...r.kernel.org, Chris Metcalf <cmetcalf@...lanox.com>
Subject: [PATCH v3 4/7] tile: support static_key usage in non-module __exit sections

From: Chris Metcalf <cmetcalf@...lanox.com>

Previously, all the __exit sections were just dropped by
the link phase.  However, if there are static_key (jump label)
constructs in __exit sections that are not modules, the link fails
with the message:

   `.exit.text' referenced in section `__jump_table' of xxx.o:
   defined in discarded section `.exit.text' of xxx.o

Support this usage by keeping the .exit.text sections in the
final image if JUMP_LABEL is defined, then discarding them
once initialization is complete.

Signed-off-by: Chris Metcalf <cmetcalf@...lanox.com>
Signed-off-by: Jason Baron <jbaron@...mai.com>
---
 arch/tile/kernel/vmlinux.lds.S | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/arch/tile/kernel/vmlinux.lds.S b/arch/tile/kernel/vmlinux.lds.S
index 378f5d8d1ec8..9d449caf8910 100644
--- a/arch/tile/kernel/vmlinux.lds.S
+++ b/arch/tile/kernel/vmlinux.lds.S
@@ -60,6 +60,18 @@ SECTIONS
   /* "Init" is divided into two areas with very different virtual addresses. */
   INIT_TEXT_SECTION(PAGE_SIZE)
 
+  /*
+   * Some things, like the __jump_table, may contain symbol references
+   * to __exit text, so include such text in the final image if so.
+   * In that case we also override the _einittext from INIT_TEXT_SECTION.
+   */
+#ifdef CONFIG_JUMP_LABEL
+  .exit.text : {
+    EXIT_TEXT
+    _einittext = .;
+  }
+#endif
+
   /* Now we skip back to PAGE_OFFSET for the data. */
   . = (. - TEXT_OFFSET + PAGE_OFFSET);
   #undef LOAD_OFFSET
-- 
2.6.1