uml: floating point signal delivery fixes

Handle floating point state in across signals correctly.  UML/i386 needs to
know whether the host does PTRACE_[GS]ETFPXREGS, so an arch_init_registers
hook is added, which on x86_64 does nothing.

UML doesn't save and restore floating point registers on kernel entry and
exit, so they need to be copied between the host process and the sigcontext.
save_fpx_registers and restore_fpx_registers are added for this purpose.
save_fp_registers and restore_fp_registers already exist.

There was a bunch of floating point state conversion code in
arch/um/sys-i386/ptrace.c which isn't needed there, but is needed in signal.c,
so it is moved over.

The i386 code now distinguishes between fp and fpx state and handles them
correctly.  The x86_64 code just needs to copy state as-is between the host
process and the stack.  There are also some fixes there to pass the correct
address of the floating point state around.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 8 insertions, 0 deletions

diff --git a/arch/um/include/registers.h b/arch/um/include/registers.h
index 8e8ea9651189..0e27406a43a4 100644
--- a/arch/um/include/registers.h
+++ b/arch/um/include/registers.h
@@ -12,6 +12,8 @@
 extern void init_thread_registers(struct uml_pt_regs *to);
 extern int save_fp_registers(int pid, unsigned long *fp_regs);
 extern int restore_fp_registers(int pid, unsigned long *fp_regs);
+extern int save_fpx_registers(int pid, unsigned long *fp_regs);
+extern int restore_fpx_registers(int pid, unsigned long *fp_regs);
 extern void save_registers(int pid, struct uml_pt_regs *regs);
 extern void restore_registers(int pid, struct uml_pt_regs *regs);
 extern void init_registers(int pid);
diff --git a/arch/um/include/sysdep-i386/ptrace.h b/arch/um/include/sysdep-i386/ptrace.h
index edb9393283b5..c16d739d2089 100644
--- a/arch/um/include/sysdep-i386/ptrace.h
+++ b/arch/um/include/sysdep-i386/ptrace.h
@@ -168,4 +168,6 @@ struct syscall_args {
 
 #define UPT_FAULTINFO(r) (&(r)->faultinfo)
 
+extern void arch_init_registers(int pid);
+
 #endif
diff --git a/arch/um/include/sysdep-x86_64/ptrace.h b/arch/um/include/sysdep-x86_64/ptrace.h
index 2ae04480ac81..7848b7dce715 100644
--- a/arch/um/include/sysdep-x86_64/ptrace.h
+++ b/arch/um/include/sysdep-x86_64/ptrace.h
@@ -234,4 +234,8 @@ struct syscall_args {
 
 #define UPT_FAULTINFO(r) (&(r)->faultinfo)
 
+static inline void arch_init_registers(int pid)
+{
+}
+
 #endif