Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 443 insertions, 0 deletions

diff --git a/arch/arc/kernel/signal.c b/arch/arc/kernel/signal.c
new file mode 100644
index 0000000000..8f6f4a5429
--- /dev/null
+++ b/arch/arc/kernel/signal.c
@@ -0,0 +1,443 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Signal Handling for ARC
+ *
+ * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
+ *
+ * vineetg: Jan 2010 (Restarting of timer related syscalls)
+ *
+ * vineetg: Nov 2009 (Everything needed for TIF_RESTORE_SIGMASK)
+ *  -do_signal() supports TIF_RESTORE_SIGMASK
+ *  -do_signal() no loner needs oldset, required by OLD sys_sigsuspend
+ *  -sys_rt_sigsuspend() now comes from generic code, so discard arch implemen
+ *  -sys_sigsuspend() no longer needs to fudge ptregs, hence that arg removed
+ *  -sys_sigsuspend() no longer loops for do_signal(), sets TIF_xxx and leaves
+ *   the job to do_signal()
+ *
+ * vineetg: July 2009
+ *  -Modified Code to support the uClibc provided userland sigreturn stub
+ *   to avoid kernel synthesing it on user stack at runtime, costing TLB
+ *   probes and Cache line flushes.
+ *
+ * vineetg: July 2009
+ *  -In stash_usr_regs( ) and restore_usr_regs( ), save/restore of user regs
+ *   in done in block copy rather than one word at a time.
+ *   This saves around 2K of code and improves LMBench lat_sig <catch>
+ *
+ * rajeshwarr: Feb 2009
+ *  - Support for Realtime Signals
+ *
+ * vineetg: Aug 11th 2008: Bug #94183
+ *  -ViXS were still seeing crashes when using insmod to load drivers.
+ *   It turned out that the code to change Execute permssions for TLB entries
+ *   of user was not guarded for interrupts (mod_tlb_permission)
+ *   This was causing TLB entries to be overwritten on unrelated indexes
+ *
+ * Vineetg: July 15th 2008: Bug #94183
+ *  -Exception happens in Delay slot of a JMP, and before user space resumes,
+ *   Signal is delivered (Ctrl + C) = >SIGINT.
+ *   setup_frame( ) sets up PC,SP,BLINK to enable user space signal handler
+ *   to run, but doesn't clear the Delay slot bit from status32. As a result,
+ *   on resuming user mode, signal handler branches off to BTA of orig JMP
+ *  -FIX: clear the DE bit from status32 in setup_frame( )
+ *
+ * Rahul Trivedi, Kanika Nema: Codito Technologies 2004
+ */
+
+#include <linux/signal.h>
+#include <linux/ptrace.h>
+#include <linux/personality.h>
+#include <linux/uaccess.h>
+#include <linux/syscalls.h>
+#include <linux/resume_user_mode.h>
+#include <linux/sched/task_stack.h>
+
+#include <asm/ucontext.h>
+#include <asm/entry.h>
+
+struct rt_sigframe {
+	struct siginfo info;
+	struct ucontext uc;
+#define MAGIC_SIGALTSTK		0x07302004
+	unsigned int sigret_magic;
+};
+
+static int save_arcv2_regs(struct sigcontext __user *mctx, struct pt_regs *regs)
+{
+	int err = 0;
+#ifndef CONFIG_ISA_ARCOMPACT
+	struct user_regs_arcv2 v2abi;
+
+	v2abi.r30 = regs->r30;
+#ifdef CONFIG_ARC_HAS_ACCL_REGS
+	v2abi.r58 = regs->r58;
+	v2abi.r59 = regs->r59;
+#else
+	v2abi.r58 = v2abi.r59 = 0;
+#endif
+	err = __copy_to_user(&mctx->v2abi, (void const *)&v2abi, sizeof(v2abi));
+#endif
+	return err;
+}
+
+static int restore_arcv2_regs(struct sigcontext __user *mctx, struct pt_regs *regs)
+{
+	int err = 0;
+#ifndef CONFIG_ISA_ARCOMPACT
+	struct user_regs_arcv2 v2abi;
+
+	err = __copy_from_user(&v2abi, &mctx->v2abi, sizeof(v2abi));
+
+	regs->r30 = v2abi.r30;
+#ifdef CONFIG_ARC_HAS_ACCL_REGS
+	regs->r58 = v2abi.r58;
+	regs->r59 = v2abi.r59;
+#endif
+#endif
+	return err;
+}
+
+static int
+stash_usr_regs(struct rt_sigframe __user *sf, struct pt_regs *regs,
+	       sigset_t *set)
+{
+	int err;
+	struct user_regs_struct uregs;
+
+	uregs.scratch.bta	= regs->bta;
+	uregs.scratch.lp_start	= regs->lp_start;
+	uregs.scratch.lp_end	= regs->lp_end;
+	uregs.scratch.lp_count	= regs->lp_count;
+	uregs.scratch.status32	= regs->status32;
+	uregs.scratch.ret	= regs->ret;
+	uregs.scratch.blink	= regs->blink;
+	uregs.scratch.fp	= regs->fp;
+	uregs.scratch.gp	= regs->r26;
+	uregs.scratch.r12	= regs->r12;
+	uregs.scratch.r11	= regs->r11;
+	uregs.scratch.r10	= regs->r10;
+	uregs.scratch.r9	= regs->r9;
+	uregs.scratch.r8	= regs->r8;
+	uregs.scratch.r7	= regs->r7;
+	uregs.scratch.r6	= regs->r6;
+	uregs.scratch.r5	= regs->r5;
+	uregs.scratch.r4	= regs->r4;
+	uregs.scratch.r3	= regs->r3;
+	uregs.scratch.r2	= regs->r2;
+	uregs.scratch.r1	= regs->r1;
+	uregs.scratch.r0	= regs->r0;
+	uregs.scratch.sp	= regs->sp;
+
+	err = __copy_to_user(&(sf->uc.uc_mcontext.regs.scratch), &uregs.scratch,
+			     sizeof(sf->uc.uc_mcontext.regs.scratch));
+
+	if (is_isa_arcv2())
+		err |= save_arcv2_regs(&(sf->uc.uc_mcontext), regs);
+
+	err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(sigset_t));
+
+	return err ? -EFAULT : 0;
+}
+
+static int restore_usr_regs(struct pt_regs *regs, struct rt_sigframe __user *sf)
+{
+	sigset_t set;
+	int err;
+	struct user_regs_struct uregs;
+
+	err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
+	err |= __copy_from_user(&uregs.scratch,
+				&(sf->uc.uc_mcontext.regs.scratch),
+				sizeof(sf->uc.uc_mcontext.regs.scratch));
+
+	if (is_isa_arcv2())
+		err |= restore_arcv2_regs(&(sf->uc.uc_mcontext), regs);
+
+	if (err)
+		return -EFAULT;
+
+	set_current_blocked(&set);
+	regs->bta	= uregs.scratch.bta;
+	regs->lp_start	= uregs.scratch.lp_start;
+	regs->lp_end	= uregs.scratch.lp_end;
+	regs->lp_count	= uregs.scratch.lp_count;
+	regs->status32	= uregs.scratch.status32;
+	regs->ret	= uregs.scratch.ret;
+	regs->blink	= uregs.scratch.blink;
+	regs->fp	= uregs.scratch.fp;
+	regs->r26	= uregs.scratch.gp;
+	regs->r12	= uregs.scratch.r12;
+	regs->r11	= uregs.scratch.r11;
+	regs->r10	= uregs.scratch.r10;
+	regs->r9	= uregs.scratch.r9;
+	regs->r8	= uregs.scratch.r8;
+	regs->r7	= uregs.scratch.r7;
+	regs->r6	= uregs.scratch.r6;
+	regs->r5	= uregs.scratch.r5;
+	regs->r4	= uregs.scratch.r4;
+	regs->r3	= uregs.scratch.r3;
+	regs->r2	= uregs.scratch.r2;
+	regs->r1	= uregs.scratch.r1;
+	regs->r0	= uregs.scratch.r0;
+	regs->sp	= uregs.scratch.sp;
+
+	return 0;
+}
+
+static inline int is_do_ss_needed(unsigned int magic)
+{
+	if (MAGIC_SIGALTSTK == magic)
+		return 1;
+	else
+		return 0;
+}
+
+SYSCALL_DEFINE0(rt_sigreturn)
+{
+	struct rt_sigframe __user *sf;
+	unsigned int magic;
+	struct pt_regs *regs = current_pt_regs();
+
+	/* Always make any pending restarted system calls return -EINTR */
+	current->restart_block.fn = do_no_restart_syscall;
+
+	/* Since we stacked the signal on a word boundary,
+	 * then 'sp' should be word aligned here.  If it's
+	 * not, then the user is trying to mess with us.
+	 */
+	if (regs->sp & 3)
+		goto badframe;
+
+	sf = (struct rt_sigframe __force __user *)(regs->sp);
+
+	if (!access_ok(sf, sizeof(*sf)))
+		goto badframe;
+
+	if (__get_user(magic, &sf->sigret_magic))
+		goto badframe;
+
+	if (unlikely(is_do_ss_needed(magic)))
+		if (restore_altstack(&sf->uc.uc_stack))
+			goto badframe;
+
+	if (restore_usr_regs(regs, sf))
+		goto badframe;
+
+	/* Don't restart from sigreturn */
+	syscall_wont_restart(regs);
+
+	/*
+	 * Ensure that sigreturn always returns to user mode (in case the
+	 * regs saved on user stack got fudged between save and sigreturn)
+	 * Otherwise it is easy to panic the kernel with a custom
+	 * signal handler and/or restorer which clobberes the status32/ret
+	 * to return to a bogus location in kernel mode.
+	 */
+	regs->status32 |= STATUS_U_MASK;
+
+	return regs->r0;
+
+badframe:
+	force_sig(SIGSEGV);
+	return 0;
+}
+
+/*
+ * Determine which stack to use..
+ */
+static inline void __user *get_sigframe(struct ksignal *ksig,
+					struct pt_regs *regs,
+					unsigned long framesize)
+{
+	unsigned long sp = sigsp(regs->sp, ksig);
+	void __user *frame;
+
+	/* No matter what happens, 'sp' must be word
+	 * aligned otherwise nasty things could happen
+	 */
+
+	/* ATPCS B01 mandates 8-byte alignment */
+	frame = (void __user *)((sp - framesize) & ~7);
+
+	/* Check that we can actually write to the signal frame */
+	if (!access_ok(frame, framesize))
+		frame = NULL;
+
+	return frame;
+}
+
+static int
+setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
+{
+	struct rt_sigframe __user *sf;
+	unsigned int magic = 0;
+	int err = 0;
+
+	sf = get_sigframe(ksig, regs, sizeof(struct rt_sigframe));
+	if (!sf)
+		return 1;
+
+	/*
+	 * w/o SA_SIGINFO, struct ucontext is partially populated (only
+	 * uc_mcontext/uc_sigmask) for kernel's normal user state preservation
+	 * during signal handler execution. This works for SA_SIGINFO as well
+	 * although the semantics are now overloaded (the same reg state can be
+	 * inspected by userland: but are they allowed to fiddle with it ?
+	 */
+	err |= stash_usr_regs(sf, regs, set);
+
+	/*
+	 * SA_SIGINFO requires 3 args to signal handler:
+	 *  #1: sig-no (common to any handler)
+	 *  #2: struct siginfo
+	 *  #3: struct ucontext (completely populated)
+	 */
+	if (unlikely(ksig->ka.sa.sa_flags & SA_SIGINFO)) {
+		err |= copy_siginfo_to_user(&sf->info, &ksig->info);
+		err |= __put_user(0, &sf->uc.uc_flags);
+		err |= __put_user(NULL, &sf->uc.uc_link);
+		err |= __save_altstack(&sf->uc.uc_stack, regs->sp);
+
+		/* setup args 2 and 3 for user mode handler */
+		regs->r1 = (unsigned long)&sf->info;
+		regs->r2 = (unsigned long)&sf->uc;
+
+		/*
+		 * small optim to avoid unconditionally calling do_sigaltstack
+		 * in sigreturn path, now that we only have rt_sigreturn
+		 */
+		magic = MAGIC_SIGALTSTK;
+	}
+
+	err |= __put_user(magic, &sf->sigret_magic);
+	if (err)
+		return err;
+
+	/* #1 arg to the user Signal handler */
+	regs->r0 = ksig->sig;
+
+	/* setup PC of user space signal handler */
+	regs->ret = (unsigned long)ksig->ka.sa.sa_handler;
+
+	/*
+	 * handler returns using sigreturn stub provided already by userspace
+	 * If not, nuke the process right away
+	 */
+	if(!(ksig->ka.sa.sa_flags & SA_RESTORER))
+		return 1;
+
+	regs->blink = (unsigned long)ksig->ka.sa.sa_restorer;
+
+	/* User Stack for signal handler will be above the frame just carved */
+	regs->sp = (unsigned long)sf;
+
+	/*
+	 * Bug 94183, Clear the DE bit, so that when signal handler
+	 * starts to run, it doesn't use BTA
+	 */
+	regs->status32 &= ~STATUS_DE_MASK;
+	regs->status32 |= STATUS_L_MASK;
+
+	return err;
+}
+
+static void arc_restart_syscall(struct k_sigaction *ka, struct pt_regs *regs)
+{
+	switch (regs->r0) {
+	case -ERESTART_RESTARTBLOCK:
+	case -ERESTARTNOHAND:
+		/*
+		 * ERESTARTNOHAND means that the syscall should
+		 * only be restarted if there was no handler for
+		 * the signal, and since we only get here if there
+		 * is a handler, we don't restart
+		 */
+		regs->r0 = -EINTR;   /* ERESTART_xxx is internal */
+		break;
+
+	case -ERESTARTSYS:
+		/*
+		 * ERESTARTSYS means to restart the syscall if
+		 * there is no handler or the handler was
+		 * registered with SA_RESTART
+		 */
+		if (!(ka->sa.sa_flags & SA_RESTART)) {
+			regs->r0 = -EINTR;
+			break;
+		}
+		fallthrough;
+
+	case -ERESTARTNOINTR:
+		/*
+		 * ERESTARTNOINTR means that the syscall should
+		 * be called again after the signal handler returns.
+		 * Setup reg state just as it was before doing the trap
+		 * r0 has been clobbered with sys call ret code thus it
+		 * needs to be reloaded with orig first arg to syscall
+		 * in orig_r0. Rest of relevant reg-file:
+		 * r8 (syscall num) and (r1 - r7) will be reset to
+		 * their orig user space value when we ret from kernel
+		 */
+		regs->r0 = regs->orig_r0;
+		regs->ret -= is_isa_arcv2() ? 2 : 4;
+		break;
+	}
+}
+
+/*
+ * OK, we're invoking a handler
+ */
+static void
+handle_signal(struct ksignal *ksig, struct pt_regs *regs)
+{
+	sigset_t *oldset = sigmask_to_save();
+	int failed;
+
+	/* Set up the stack frame */
+	failed = setup_rt_frame(ksig, oldset, regs);
+
+	signal_setup_done(failed, ksig, 0);
+}
+
+void do_signal(struct pt_regs *regs)
+{
+	struct ksignal ksig;
+	int restart_scall;
+
+	restart_scall = in_syscall(regs) && syscall_restartable(regs);
+
+	if (test_thread_flag(TIF_SIGPENDING) && get_signal(&ksig)) {
+		if (restart_scall) {
+			arc_restart_syscall(&ksig.ka, regs);
+			syscall_wont_restart(regs);	/* No more restarts */
+		}
+		handle_signal(&ksig, regs);
+		return;
+	}
+
+	if (restart_scall) {
+		/* No handler for syscall: restart it */
+		if (regs->r0 == -ERESTARTNOHAND ||
+		    regs->r0 == -ERESTARTSYS || regs->r0 == -ERESTARTNOINTR) {
+			regs->r0 = regs->orig_r0;
+			regs->ret -= is_isa_arcv2() ? 2 : 4;
+		} else if (regs->r0 == -ERESTART_RESTARTBLOCK) {
+			regs->r8 = __NR_restart_syscall;
+			regs->ret -= is_isa_arcv2() ? 2 : 4;
+		}
+		syscall_wont_restart(regs);	/* No more restarts */
+	}
+
+	/* If there's no signal to deliver, restore the saved sigmask back */
+	restore_saved_sigmask();
+}
+
+void do_notify_resume(struct pt_regs *regs)
+{
+	/*
+	 * ASM glue guarantees that this is only called when returning to
+	 * user mode
+	 */
+	if (test_thread_flag(TIF_NOTIFY_RESUME))
+		resume_user_mode_work(regs);
+}