compel: Add ctx flags to get_task_regs()

get_task_regs() needs to know if it needs to use workaround
for a Skylake ptrace() bug. The next patch will introduce a
new flag for that.
I also thought about making 3 versions of get_task_regs() and
adding them to ictx->get_task_regs() depending on the flags..
But get_task_regs() is a private function and infect_ctx is
a uapi.. So, let's just pass context flags to get_task_regs().
Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>

compel/arch/aarch64/src/lib/infect.c

@@ -57,7 +57,8 @@ int sigreturn_prep_fpu_frame_plain(struct rt_sigframe *sigframe,
 	return 0;
 }
 
-int get_task_regs(pid_t pid, user_regs_struct_t *regs, save_regs_t save, void *arg)
+int get_task_regs(pid_t pid, user_regs_struct_t *regs, save_regs_t save,
+		  void *arg, __maybe_unused unsigned long flags)
 {
 	struct iovec iov;
 	user_fpregs_struct_t fpsimd;

compel/arch/arm/src/lib/infect.c

@@ -66,7 +66,8 @@ int sigreturn_prep_fpu_frame_plain(struct rt_sigframe *sigframe,
 }
 
 #define PTRACE_GETVFPREGS 27
-int get_task_regs(pid_t pid, user_regs_struct_t *regs, save_regs_t save, void *arg)
+int get_task_regs(pid_t pid, user_regs_struct_t *regs, save_regs_t save,
+		  void *arg, __maybe_unused unsigned long flags)
 {
 	user_fpregs_struct_t vfp;
 	int ret = -1;

compel/arch/ppc64/src/lib/infect.c

@@ -371,7 +371,8 @@ static int __get_task_regs(pid_t pid, user_regs_struct_t *regs,
 	return 0;
 }
 
-int get_task_regs(pid_t pid, user_regs_struct_t *regs, save_regs_t save, void *arg)
+int get_task_regs(pid_t pid, user_regs_struct_t *regs, save_regs_t save,
+		  void *arg, __maybe_unused unsigned long flags)
 {
 	user_fpregs_struct_t fpregs;
 	int ret;

compel/arch/s390/src/lib/infect.c

@@ -312,7 +312,7 @@ static int s390_disable_ri_bit(pid_t pid, user_regs_struct_t *regs)
  * Prepare task registers for restart
  */
 int get_task_regs(pid_t pid, user_regs_struct_t *regs, save_regs_t save,
-		  void *arg)
+		  void *arg, __maybe_unused unsigned long flags)
 {
 	user_fpregs_struct_t fpregs;
 	struct iovec iov;

compel/arch/x86/src/lib/infect.c

@@ -225,7 +225,8 @@ int sigreturn_prep_fpu_frame_plain(struct rt_sigframe *sigframe,
 	((user_regs_native(pregs)) ? (int64_t)((pregs)->native.name) :	\
 				(int32_t)((pregs)->compat.name))
 
-int get_task_regs(pid_t pid, user_regs_struct_t *regs, save_regs_t save, void *arg)
+int get_task_regs(pid_t pid, user_regs_struct_t *regs, save_regs_t save,
+		  void *arg, __maybe_unused unsigned long flags)
 {
 	user_fpregs_struct_t xsave	= {  }, *xs = NULL;
 

compel/include/infect-priv.h

@@ -58,7 +58,8 @@ extern void *remote_mmap(struct parasite_ctl *ctl,
 		void *addr, size_t length, int prot,
 		int flags, int fd, off_t offset);
 extern bool arch_can_dump_task(struct parasite_ctl *ctl);
-extern int get_task_regs(pid_t pid, user_regs_struct_t *regs, save_regs_t save, void *arg);
+extern int get_task_regs(pid_t pid, user_regs_struct_t *regs, save_regs_t save,
+			void *arg, unsigned long flags);
 extern int arch_fetch_sas(struct parasite_ctl *ctl, struct rt_sigframe *s);
 extern int sigreturn_prep_regs_plain(struct rt_sigframe *sigframe,
 				     user_regs_struct_t *regs,

compel/src/lib/infect.c

@@ -667,7 +667,8 @@ static int parasite_start_daemon(struct parasite_ctl *ctl)
 	 * while in daemon it is not such.
 	 */
 
-	if (get_task_regs(pid, &ctl->orig.regs, ictx->save_regs, ictx->regs_arg)) {
+	if (get_task_regs(pid, &ctl->orig.regs, ictx->save_regs,
+			ictx->regs_arg, ictx->flags)) {
 		pr_err("Can't obtain regs for thread %d\n", pid);
 		return -1;
 	}
@@ -1569,7 +1570,7 @@ k_rtsigset_t *compel_task_sigmask(struct parasite_ctl *ctl)
 
 int compel_get_thread_regs(struct parasite_thread_ctl *tctl, save_regs_t save, void * arg)
 {
-	return get_task_regs(tctl->tid, &tctl->th.regs, save, arg);
+	return get_task_regs(tctl->tid, &tctl->th.regs, save, arg, tctl->ctl->ictx.flags);
 }
 
 struct infect_ctx *compel_infect_ctx(struct parasite_ctl *ctl)