restore: Add some more structures for frame setup

Some of them are already in system header files
but until I debug all things I simply picked up
kernel's definitions just to be more-less safe.
Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>

include/restorer.h

@@ -3,8 +3,14 @@
 
 #include <signal.h>
 
+#include "compiler.h"
+#include "types.h"
 #include "image.h"
 
+#ifndef CONFIG_X86_64
+# error Only x86-64 is supported
+#endif
+
 #define RESTORER_ARGS_SIZE	512
 #define RESTORER_STACK_MIDDLE	(16 << 10)
 #define RESTORER_STACK_SIZE	(RESTORER_STACK_MIDDLE * 2)
@@ -19,6 +25,13 @@ typedef long (*restorer_fcall_t) (long cmd);
 #define RESTORER_CMD__PR_ARG_STRING	3
 #define RESTORER_CMD__RESTORE_CORE	4
 
+#define ABI_RED_ZONE 128
+
+#define align_sigframe(sp)			\
+	do {					\
+		sp = round_down(sp, 16) - 8;	\
+	} while (0)
+
 struct restore_core_args {
 	void	*self_entry;		/* restorer placed at */
 	long	self_size;		/* size for restorer granted */
@@ -26,10 +39,75 @@ struct restore_core_args {
 	char	self_vmas_path[64];	/* path to a self-vmas file */
 };
 
+struct rt_sigcontext {
+	unsigned long			r8;
+	unsigned long			r9;
+	unsigned long			r10;
+	unsigned long			r11;
+	unsigned long			r12;
+	unsigned long			r13;
+	unsigned long			r14;
+	unsigned long			r15;
+	unsigned long			rdi;
+	unsigned long			rsi;
+	unsigned long			rbp;
+	unsigned long			rbx;
+	unsigned long			rdx;
+	unsigned long			rax;
+	unsigned long			rcx;
+	unsigned long			rsp;
+	unsigned long			rip;
+	unsigned long			eflags;
+	unsigned short			cs;
+	unsigned short			gs;
+	unsigned short			fs;
+	unsigned short			__pad0;
+	unsigned long			err;
+	unsigned long			trapno;
+	unsigned long			oldmask;
+	unsigned long			cr2;
+	struct user_fpregs_entry	*fpstate;
+	unsigned long			reserved1[8];
+};
+
+#ifndef __ARCH_SI_PREAMBLE_SIZE
+#define __ARCH_SI_PREAMBLE_SIZE	(3 * sizeof(int))
+#endif
+
+#define SI_MAX_SIZE	128
+#ifndef SI_PAD_SIZE
+#define SI_PAD_SIZE	((SI_MAX_SIZE - __ARCH_SI_PREAMBLE_SIZE) / sizeof(int))
+#endif
+
+typedef struct rt_siginfo {
+	int	si_signo;
+	int	si_errno;
+	int	si_code;
+	int	_pad[SI_PAD_SIZE];
+} rt_siginfo_t;
+
+typedef struct {
+	unsigned long sig[1];
+} rt_sigset_t;
+
+typedef struct rt_sigaltstack {
+	void	*ss_sp;
+	int	ss_flags;
+	size_t	ss_size;
+} rt_stack_t;
+
+struct rt_ucontext {
+	unsigned long		uc_flags;
+	struct rt_ucontext	*uc_link;
+	rt_stack_t		uc_stack;
+	struct rt_sigcontext	uc_mcontext;
+	rt_sigset_t		uc_sigmask;	/* mask last for extensibility */
+};
+
 struct rt_sigframe {
 	char			*pretcode;
-	struct ucontext		uc;
-	struct siginfo		info;
+	struct rt_ucontext	uc;
+	struct rt_siginfo	info;
 
 	/* fp state follows here */
 };

restorer.c

@@ -37,6 +37,13 @@
 			c += 'a' - 10;	\
 	} while (0)
 
+#define inline_memcpy(d,s,l)	__builtin_memcpy(d,s,l)
+#define inline_memset(d,c,l)	__builtin_memset(d,c,l)
+#define inline_memzero(d,l)	__builtin_memset(d,0,l)
+#define inline_memzero_p(d)	__builtin_memset(d,0,sizeof(*(d)))
+
+#define cp_reg(d,s,r)		d->r = s->r
+
 static void always_inline write_char(char c)
 {
 	sys_write(1, &c, 1);
@@ -143,7 +150,9 @@ self_len_end:
 		struct vma_entry vma_entry;
 		u64 va;
 
-		struct rt_sigframe *frame;
+		struct user_fpregs_entry *fpregs;
+		struct user_regs_entry *gpregs;
+		struct rt_sigframe *rt_sigframe;
 
 		lea_args_off(args);
 
@@ -188,6 +197,7 @@ self_len_end:
 		}
 
 		sys_close(fd_self_vmas);
+		sys_unlink(args->self_vmas_path);
 
 		/*
 		 * OK, lets try to map new one.
@@ -295,6 +305,33 @@ self_len_end:
 
 		goto core_restore_end;
 
+		/*
+		 * We need to prepare a valid sigframe here, so
+		 * after sigreturn the kernel will pick up the
+		 * registers from the frame, set them up and
+		 * finally pass execution to the new IP.
+		 */
+
+		/*
+		 * The sigframe should be on the stack, also
+		 * note the kernel uses this stack not only
+		 * for restoring registers and such but it
+		 * save pt_regs there after sigframe, so make
+		 * sure the stack is big enough to keep all
+		 * this, otherwise the application get killed
+		 * by the kernel with stack overflow error.
+		 */
+
+		/*
+		 * Reuse arguments space for own needs,
+		 * no more arguments needed so lets try
+		 * to be thrifty with memory usage.
+		*/
+		lea_args_off(rt_sigframe);
+		inline_memzero_p(rt_sigframe);
+
+		
+
 		/* Finally call for sigreturn */
 		sys_rt_sigreturn();