compel: pass regs by pointer in get_task_regs()

CID 73371 (#1 of 1): Big parameter passed by value (PASS_BY_VALUE)
pass_by_value: Passing parameter regs of type user_regs_struct_t
(size 224 bytes) by value.

Suggesting to do this until compel is released and API is cut in stone.
Signed-off-by: Dmitry Safonov <dsafonov@virtuozzo.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>

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

@@ -56,7 +56,7 @@ 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)
 {
 	struct iovec iov;
 	user_fpregs_struct_t fpsimd;
@@ -64,7 +64,7 @@ int get_task_regs(pid_t pid, user_regs_struct_t regs, save_regs_t save, void *ar
 
 	pr_info("Dumping GP/FPU registers for %d\n", pid);
 
-	iov.iov_base = &regs;
+	iov.iov_base = regs;
 	iov.iov_len = sizeof(user_regs_struct_t);
 	if ((ret = ptrace(PTRACE_GETREGSET, pid, NT_PRSTATUS, &iov))) {
 		pr_perror("Failed to obtain CPU registers for %d", pid);
@@ -78,7 +78,7 @@ int get_task_regs(pid_t pid, user_regs_struct_t regs, save_regs_t save, void *ar
 		goto err;
 	}
 
-	ret = save(arg, &regs, &fpsimd);
+	ret = save(arg, regs, &fpsimd);
 err:
 	return ret;
 }

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

@@ -65,7 +65,7 @@ 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)
 {
 	user_fpregs_struct_t vfp;
 	int ret = -1;
@@ -78,23 +78,23 @@ int get_task_regs(pid_t pid, user_regs_struct_t regs, save_regs_t save, void *ar
 	}
 
 	/* Did we come from a system call? */
-	if ((int)regs.ARM_ORIG_r0 >= 0) {
+	if ((int)regs->ARM_ORIG_r0 >= 0) {
 		/* Restart the system call */
-		switch ((long)(int)regs.ARM_r0) {
+		switch ((long)(int)regs->ARM_r0) {
 		case -ERESTARTNOHAND:
 		case -ERESTARTSYS:
 		case -ERESTARTNOINTR:
-			regs.ARM_r0 = regs.ARM_ORIG_r0;
-			regs.ARM_pc -= 4;
+			regs->ARM_r0 = regs->ARM_ORIG_r0;
+			regs->ARM_pc -= 4;
 			break;
 		case -ERESTART_RESTARTBLOCK:
-			regs.ARM_r0 = __NR_restart_syscall;
-			regs.ARM_pc -= 4;
+			regs->ARM_r0 = __NR_restart_syscall;
+			regs->ARM_pc -= 4;
 			break;
 		}
 	}
 
-	ret = save(arg, &regs, &vfp);
+	ret = save(arg, regs, &vfp);
 err:
 	return ret;
 }

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

@@ -369,16 +369,16 @@ 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)
 {
 	user_fpregs_struct_t fpregs;
 	int ret;
 
-	ret = __get_task_regs(pid, &regs, &fpregs);
+	ret = __get_task_regs(pid, regs, &fpregs);
 	if (ret)
 		return ret;
 
-	return save(arg, &regs, &fpregs);
+	return save(arg, regs, &fpregs);
 }
 
 int compel_syscall(struct parasite_ctl *ctl, int nr, long *ret,

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

@@ -225,7 +225,7 @@ 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)
 {
 	user_fpregs_struct_t xsave	= {  }, *xs = NULL;
 
@@ -233,21 +233,21 @@ int get_task_regs(pid_t pid, user_regs_struct_t regs, save_regs_t save, void *ar
 	int ret = -1;
 
 	pr_info("Dumping general registers for %d in %s mode\n", pid,
-			user_regs_native(&regs) ? "native" : "compat");
+			user_regs_native(regs) ? "native" : "compat");
 
 	/* Did we come from a system call? */
-	if (get_signed_user_reg(&regs, orig_ax) >= 0) {
+	if (get_signed_user_reg(regs, orig_ax) >= 0) {
 		/* Restart the system call */
-		switch (get_signed_user_reg(&regs, ax)) {
+		switch (get_signed_user_reg(regs, ax)) {
 		case -ERESTARTNOHAND:
 		case -ERESTARTSYS:
 		case -ERESTARTNOINTR:
-			set_user_reg(&regs, ax, get_user_reg(&regs, orig_ax));
-			set_user_reg(&regs, ip, get_user_reg(&regs, ip) - 2);
+			set_user_reg(regs, ax, get_user_reg(regs, orig_ax));
+			set_user_reg(regs, ip, get_user_reg(regs, ip) - 2);
 			break;
 		case -ERESTART_RESTARTBLOCK:
 			pr_warn("Will restore %d with interrupted system call\n", pid);
-			set_user_reg(&regs, ax, -EINTR);
+			set_user_reg(regs, ax, -EINTR);
 			break;
 		}
 	}
@@ -279,7 +279,7 @@ int get_task_regs(pid_t pid, user_regs_struct_t regs, save_regs_t save, void *ar
 
 	xs = &xsave;
 out:
-	ret = save(arg, &regs, xs);
+	ret = save(arg, regs, xs);
 err:
 	return ret;
 }

compel/include/infect-priv.h

@@ -58,7 +58,7 @@ 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);
 extern int sigreturn_prep_regs_plain(struct rt_sigframe *sigframe,
 				     user_regs_struct_t *regs,
 				     user_fpregs_struct_t *fpregs);

compel/src/lib/infect.c

@@ -664,7 +664,7 @@ 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)) {
 		pr_err("Can't obtain regs for thread %d\n", pid);
 		return -1;
 	}
@@ -1556,7 +1556,7 @@ 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);
 }
 
 struct infect_ctx *compel_infect_ctx(struct parasite_ctl *ctl)