x86/prctl: Remove pointless task argument

The functions invoked via do_arch_prctl_common() can only operate on
the current task and none of these function uses the task argument.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/87lev7vtxj.ffs@tglx

Author: KAGA-KOKO

arch/x86/include/asm/fpu/api.h

@@ -162,7 +162,6 @@ static inline bool fpstate_is_confidential(struct fpu_guest *gfpu)
 }
 
 /* prctl */
-struct task_struct;
-extern long fpu_xstate_prctl(struct task_struct *tsk, int option, unsigned long arg2);
+extern long fpu_xstate_prctl(int option, unsigned long arg2);
 
 #endif /* _ASM_X86_FPU_API_H */

arch/x86/include/asm/proto.h

@@ -39,7 +39,6 @@ void x86_report_nx(void);
 
 extern int reboot_force;
 
-long do_arch_prctl_common(struct task_struct *task, int option,
-			  unsigned long arg2);
+long do_arch_prctl_common(int option, unsigned long arg2);
 
 #endif /* _ASM_X86_PROTO_H */

arch/x86/kernel/fpu/xstate.c

@@ -1687,16 +1687,13 @@ EXPORT_SYMBOL_GPL(xstate_get_guest_group_perm);
  * e.g. for AMX which requires XFEATURE_XTILE_CFG(17) and
  * XFEATURE_XTILE_DATA(18) this would be XFEATURE_XTILE_DATA(18).
  */
-long fpu_xstate_prctl(struct task_struct *tsk, int option, unsigned long arg2)
+long fpu_xstate_prctl(int option, unsigned long arg2)
 {
 	u64 __user *uptr = (u64 __user *)arg2;
 	u64 permitted, supported;
 	unsigned long idx = arg2;
 	bool guest = false;
 
-	if (tsk != current)
-		return -EPERM;
-
 	switch (option) {
 	case ARCH_GET_XCOMP_SUPP:
 		supported = fpu_user_cfg.max_features |	fpu_user_cfg.legacy_features;

arch/x86/kernel/process.c

@@ -334,7 +334,7 @@ static int get_cpuid_mode(void)
 	return !test_thread_flag(TIF_NOCPUID);
 }
 
-static int set_cpuid_mode(struct task_struct *task, unsigned long cpuid_enabled)
+static int set_cpuid_mode(unsigned long cpuid_enabled)
 {
 	if (!boot_cpu_has(X86_FEATURE_CPUID_FAULT))
 		return -ENODEV;
@@ -985,20 +985,19 @@ unsigned long __get_wchan(struct task_struct *p)
 	return addr;
 }
 
-long do_arch_prctl_common(struct task_struct *task, int option,
-			  unsigned long arg2)
+long do_arch_prctl_common(int option, unsigned long arg2)
 {
 	switch (option) {
 	case ARCH_GET_CPUID:
 		return get_cpuid_mode();
 	case ARCH_SET_CPUID:
-		return set_cpuid_mode(task, arg2);
+		return set_cpuid_mode(arg2);
 	case ARCH_GET_XCOMP_SUPP:
 	case ARCH_GET_XCOMP_PERM:
 	case ARCH_REQ_XCOMP_PERM:
 	case ARCH_GET_XCOMP_GUEST_PERM:
 	case ARCH_REQ_XCOMP_GUEST_PERM:
-		return fpu_xstate_prctl(task, option, arg2);
+		return fpu_xstate_prctl(option, arg2);
 	}
 
 	return -EINVAL;

arch/x86/kernel/process_32.c

@@ -222,5 +222,5 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
 
 SYSCALL_DEFINE2(arch_prctl, int, option, unsigned long, arg2)
 {
-	return do_arch_prctl_common(current, option, arg2);
+	return do_arch_prctl_common(option, arg2);
 }

arch/x86/kernel/process_64.c

@@ -844,15 +844,15 @@ SYSCALL_DEFINE2(arch_prctl, int, option, unsigned long, arg2)
 
 	ret = do_arch_prctl_64(current, option, arg2);
 	if (ret == -EINVAL)
-		ret = do_arch_prctl_common(current, option, arg2);
+		ret = do_arch_prctl_common(option, arg2);
 
 	return ret;
 }
 
 #ifdef CONFIG_IA32_EMULATION
 COMPAT_SYSCALL_DEFINE2(arch_prctl, int, option, unsigned long, arg2)
 {
-	return do_arch_prctl_common(current, option, arg2);
+	return do_arch_prctl_common(option, arg2);
 }
 #endif