uml: fix x86_64 core dump crash

Stop UML crashing when trying to dump a process core on x86_64.  This is the
minimal fix to stop the crash - more things are broken here, and patches are
forthcoming.

The immediate thing to do is define ELF_CORE_COPY_REGS and
ELF_CORE_COPY_FPREGS.  Defining ELF_CORE_COPY_FPREGS allows dump_fpu to go
away.  It is defined in terms of save_fp_registers, so that needs to be added.

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>

2 files changed, 15 insertions, 6 deletions

diff --git a/arch/um/os-Linux/sys-x86_64/registers.c b/arch/um/os-Linux/sys-x86_64/registers.c
index e6fc217..9467315 100644
--- a/arch/um/os-Linux/sys-x86_64/registers.c
+++ b/arch/um/os-Linux/sys-x86_64/registers.c
@@ -4,6 +4,7 @@
  */
 
 #include <errno.h>
+#include <sys/ptrace.h>
 #include <string.h>
 #include "ptrace_user.h"
 #include "uml-config.h"
@@ -17,6 +18,20 @@
 static unsigned long exec_regs[MAX_REG_NR];
 static unsigned long exec_fp_regs[HOST_FP_SIZE];
 
+int save_fp_registers(int pid, unsigned long *fp_regs)
+{
+	if(ptrace(PTRACE_GETFPREGS, pid, 0, fp_regs) < 0)
+		return -errno;
+	return 0;
+}
+
+int restore_fp_registers(int pid, unsigned long *fp_regs)
+{
+	if(ptrace(PTRACE_SETFPREGS, pid, 0, fp_regs) < 0)
+		return -errno;
+	return 0;
+}
+
 void init_thread_registers(union uml_pt_regs *to)
 {
 	memcpy(to->skas.regs, exec_regs, sizeof(to->skas.regs));
diff --git a/arch/um/sys-x86_64/ptrace.c b/arch/um/sys-x86_64/ptrace.c
index 55b66e0..1970d78 100644
--- a/arch/um/sys-x86_64/ptrace.c
+++ b/arch/um/sys-x86_64/ptrace.c
@@ -156,12 +156,6 @@ int is_syscall(unsigned long addr)
 	return(instr == 0x050f);
 }
 
-int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu )
-{
-	panic("dump_fpu");
-	return(1);
-}
-
 int get_fpregs(unsigned long buf, struct task_struct *child)
 {
 	panic("get_fpregs");