[PATCH v2 4/8] x86: add .broken section to the vDSO linker script

From: Petr Tesarik
Date: Fri Jun 12 2009 - 09:46:32 EST


This section should not contain anything unless the vDSO is
broken. It is intended to hold sections which are known not
to work correctly inside a vDSO.

If such a "broken" section is found at link-time, the linker
issues an error with a hint how to find out more.

Signed-off-by: Petr Tesarik <ptesarik@xxxxxxx>
---
arch/x86/vdso/vdso-layout.lds.S | 22 ++++++++++++++++++++++
1 files changed, 22 insertions(+), 0 deletions(-)

diff --git a/arch/x86/vdso/vdso-layout.lds.S b/arch/x86/vdso/vdso-layout.lds.S
index c7fa74c..7a76159 100644
--- a/arch/x86/vdso/vdso-layout.lds.S
+++ b/arch/x86/vdso/vdso-layout.lds.S
@@ -72,8 +72,30 @@ SECTIONS
.text : {
*(.text*)
} :text =0x90909090
+
+ /* Some sections require some additional work from the dynamic
+ * linker to work properly. However, there is no dynamic-link
+ * pass for the vDSO, so these sections will not work.
+ * Put them into a special section and raise a link-time error
+ * if they get used by accident.
+ */
+ .broken : {
+ }
}

+/* This assert is triggered if the linker finds a section in one of its
+ * input files which is known not to work inside a vDSO.
+ *
+ * To see which is the offending sections, you may:
+ * a. use objdump -h on the object files which make up the vDSO, or
+ * b. add -Wl,-M to VDSO_LDFLAGS and examine the linker map.
+ *
+ * See individual comments in the definition of the .broken section
+ * above for more information on why any given section is considered
+ * "broken".
+ */
+ASSERT(!SIZEOF(.broken), "The vdso linker script found a section that is bad. See vdso-layout.lds.S for details.");
+
/*
* Very old versions of ld do not recognize this name token; use the constant.
*/
--
1.6.0.2

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