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[ARM/FDPIC,14/21,ARM] FDPIC: Force LSB bit for PC in Cortex-M architecture

Message ID 20180525080354.13295-15-christophe.lyon@st.com
State Superseded
Headers show
Series FDPIC ARM for ARM | expand

Commit Message

Christophe Lyon May 25, 2018, 8:03 a.m. UTC 
Without this, when we are unwinding across a signal frame we can jump
to an even address which leads to an exception.

This is needed in __gnu_persnality_sigframe_fdpic() when restoring the
PC from the signal frame since the PC saved by the kernel has the LSB
bit set to zero.

2018-XX-XX  Christophe Lyon  <christophe.lyon@st.com>
	Mickaël Guêné <mickael.guene@st.com>

	libgcc/
	* config/arm/unwind-arm.c (_Unwind_VRS_Set): Handle v7m
	architecture.

Change-Id: Ie84de548226bcf1751e19a09e8f091fb3013ccea

-- 
2.6.3
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Patch

diff --git a/libgcc/config/arm/unwind-arm.c b/libgcc/config/arm/unwind-arm.c
index 564e4f13..6da6e3d 100644
--- a/libgcc/config/arm/unwind-arm.c
+++ b/libgcc/config/arm/unwind-arm.c
@@ -198,6 +198,11 @@  _Unwind_VRS_Result _Unwind_VRS_Set (_Unwind_Context *context,
 	return _UVRSR_FAILED;
 
       vrs->core.r[regno] = *(_uw *) valuep;
+#if defined(__ARM_ARCH_7M__)
+      /* Force LSB bit since we always run thumb code.  */
+      if (regno == 15)
+	vrs->core.r[regno] |= 1;
+#endif
       return _UVRSR_OK;
 
     case _UVRSC_VFP: