ARM: 6051/1: VFP: preserve the HW context when calling signal handlers

From: Imre Deak <imre.deak@nokia.com>

Signal handlers can use floating point, so prevent them to corrupt
the main thread's VFP context. So far there were two signal stack
frame formats defined based on the VFP implementation, but the user
struct used for ptrace covers all posibilities, so use it for the
signal stack too.

Introduce also a new user struct for VFP exception registers. In
this too fields not relevant to the current VFP architecture are
ignored.

Support to save / restore the exception registers was added by
Will Deacon.

Signed-off-by: Imre Deak <imre.deak@nokia.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 11 insertions, 1 deletions

diff --git a/arch/arm/include/asm/user.h b/arch/arm/include/asm/user.h
index df95e050f9dd..05ac4b06876a 100644
--- a/arch/arm/include/asm/user.h
+++ b/arch/arm/include/asm/user.h
@@ -83,11 +83,21 @@ struct user{
 
 /*
  * User specific VFP registers. If only VFPv2 is present, registers 16 to 31
- * are ignored by the ptrace system call.
+ * are ignored by the ptrace system call and the signal handler.
  */
 struct user_vfp {
 	unsigned long long fpregs[32];
 	unsigned long fpscr;
 };
 
+/*
+ * VFP exception registers exposed to user space during signal delivery.
+ * Fields not relavant to the current VFP architecture are ignored.
+ */
+struct user_vfp_exc {
+	unsigned long	fpexc;
+	unsigned long	fpinst;
+	unsigned long	fpinst2;
+};
+
 #endif /* _ARM_USER_H */