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2023-12-09 95099d4622f8cb224d94e314c7a8e0df60b13f87

 kernel/arch/powerpc/kernel/signal_64.c
..
..
@@ -1,3 +1,4 @@
1
+// SPDX-License-Identifier: GPL-2.0-or-later
1
2
 /*
2
3
  *  PowerPC version 
3
4
  *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
..
..
@@ -5,11 +6,6 @@
5
6
  *  Derived from "arch/i386/kernel/signal.c"
6
7
  *    Copyright (C) 1991, 1992 Linus Torvalds
7
8
  *    1997-11-28  Modified for POSIX.1b signals by Richard Henderson
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- *
9
- *  This program is free software; you can redistribute it and/or
10
- *  modify it under the terms of the GNU General Public License
11
- *  as published by the Free Software Foundation; either version
12
- *  2 of the License, or (at your option) any later version.
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9
  */
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10
 
15
11
 #include <linux/sched.h>
..
..
@@ -25,11 +21,11 @@
25
21
 #include <linux/ptrace.h>
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22
 #include <linux/ratelimit.h>
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23
 #include <linux/syscalls.h>
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+#include <linux/pagemap.h>
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25
 
29
26
 #include <asm/sigcontext.h>
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27
 #include <asm/ucontext.h>
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28
 #include <linux/uaccess.h>
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-#include <asm/pgtable.h>
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 #include <asm/unistd.h>
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30
 #include <asm/cacheflush.h>
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31
 #include <asm/syscalls.h>
..
..
@@ -44,8 +40,8 @@
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40
 #define GP_REGS_SIZE	min(sizeof(elf_gregset_t), sizeof(struct pt_regs))
45
41
 #define FP_REGS_SIZE	sizeof(elf_fpregset_t)
46
42
 
47
-#define TRAMP_TRACEBACK	3
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-#define TRAMP_SIZE	6
43
+#define TRAMP_TRACEBACK	4
44
+#define TRAMP_SIZE	7
49
45
 
50
46
 /*
51
47
  * When we have signals to deliver, we set up on the user stack,
..
..
@@ -354,8 +350,8 @@
354
350
 	err |= __get_user(regs->link, &sc->gp_regs[PT_LNK]);
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351
 	err |= __get_user(regs->xer, &sc->gp_regs[PT_XER]);
356
352
 	err |= __get_user(regs->ccr, &sc->gp_regs[PT_CCR]);
357
-	/* skip SOFTE */
358
-	regs->trap = 0;
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+	/* Don't allow userspace to set SOFTE */
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+	set_trap_norestart(regs);
359
355
 	err |= __get_user(regs->dar, &sc->gp_regs[PT_DAR]);
360
356
 	err |= __get_user(regs->dsisr, &sc->gp_regs[PT_DSISR]);
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357
 	err |= __get_user(regs->result, &sc->gp_regs[PT_RESULT]);
..
..
@@ -376,7 +372,7 @@
376
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 	err |= __get_user(v_regs, &sc->v_regs);
377
373
 	if (err)
378
374
 		return err;
379
-	if (v_regs && !access_ok(VERIFY_READ, v_regs, 34 * sizeof(vector128)))
375
+	if (v_regs && !access_ok(v_regs, 34 * sizeof(vector128)))
380
376
 		return -EFAULT;
381
377
 	/* Copy 33 vec registers (vr0..31 and vscr) from the stack */
382
378
 	if (v_regs != NULL && (msr & MSR_VEC) != 0) {
..
..
@@ -476,10 +472,8 @@
476
472
 			  &sc->gp_regs[PT_XER]);
477
473
 	err |= __get_user(tsk->thread.ckpt_regs.ccr,
478
474
 			  &sc->gp_regs[PT_CCR]);
479
-
480
-	/* Don't allow userspace to set the trap value */
481
-	regs->trap = 0;
482
-
475
+	/* Don't allow userspace to set SOFTE */
476
+	set_trap_norestart(regs);
483
477
 	/* These regs are not checkpointed; they can go in 'regs'. */
484
478
 	err |= __get_user(regs->dar, &sc->gp_regs[PT_DAR]);
485
479
 	err |= __get_user(regs->dsisr, &sc->gp_regs[PT_DSISR]);
..
..
@@ -497,10 +491,9 @@
497
491
 	err |= __get_user(tm_v_regs, &tm_sc->v_regs);
498
492
 	if (err)
499
493
 		return err;
500
-	if (v_regs && !access_ok(VERIFY_READ, v_regs, 34 * sizeof(vector128)))
494
+	if (v_regs && !access_ok(v_regs, 34 * sizeof(vector128)))
501
495
 		return -EFAULT;
502
-	if (tm_v_regs && !access_ok(VERIFY_READ,
503
-				    tm_v_regs, 34 * sizeof(vector128)))
496
+	if (tm_v_regs && !access_ok(tm_v_regs, 34 * sizeof(vector128)))
504
497
 		return -EFAULT;
505
498
 	/* Copy 33 vec registers (vr0..31 and vscr) from the stack */
506
499
 	if (v_regs != NULL && tm_v_regs != NULL && (msr & MSR_VEC) != 0) {
..
..
@@ -561,7 +554,7 @@
561
554
 	preempt_disable();
562
555
 
563
556
 	/* pull in MSR TS bits from user context */
564
-	regs->msr = (regs->msr & ~MSR_TS_MASK) | (msr & MSR_TS_MASK);
557
+	regs->msr |= msr & MSR_TS_MASK;
565
558
 
566
559
 	/*
567
560
 	 * Ensure that TM is enabled in regs->msr before we leave the signal
..
..
@@ -608,12 +601,15 @@
608
601
 	int i;
609
602
 	long err = 0;
610
603
 
604
+	/* bctrl # call the handler */
605
+	err |= __put_user(PPC_INST_BCTRL, &tramp[0]);
611
606
 	/* addi r1, r1, __SIGNAL_FRAMESIZE  # Pop the dummy stackframe */
612
-	err |= __put_user(0x38210000UL | (__SIGNAL_FRAMESIZE & 0xffff), &tramp[0]);
607
+	err |= __put_user(PPC_INST_ADDI | __PPC_RT(R1) | __PPC_RA(R1) |
608
+			  (__SIGNAL_FRAMESIZE & 0xffff), &tramp[1]);
613
609
 	/* li r0, __NR_[rt_]sigreturn| */
614
-	err |= __put_user(0x38000000UL | (syscall & 0xffff), &tramp[1]);
610
+	err |= __put_user(PPC_INST_ADDI | (syscall & 0xffff), &tramp[2]);
615
611
 	/* sc */
616
-	err |= __put_user(0x44000002UL, &tramp[2]);
612
+	err |= __put_user(PPC_INST_SC, &tramp[3]);
617
613
 
618
614
 	/* Minimal traceback info */
619
615
 	for (i=TRAMP_TRACEBACK; i < TRAMP_SIZE ;i++)
..
..
@@ -639,7 +635,6 @@
639
635
 SYSCALL_DEFINE3(swapcontext, struct ucontext __user *, old_ctx,
640
636
 		struct ucontext __user *, new_ctx, long, ctx_size)
641
637
 {
642
-	unsigned char tmp;
643
638
 	sigset_t set;
644
639
 	unsigned long new_msr = 0;
645
640
 	int ctx_has_vsx_region = 0;
..
..
@@ -665,7 +660,7 @@
665
660
 		ctx_has_vsx_region = 1;
666
661
 
667
662
 	if (old_ctx != NULL) {
668
-		if (!access_ok(VERIFY_WRITE, old_ctx, ctx_size)
663
+		if (!access_ok(old_ctx, ctx_size)
669
664
 		    || setup_sigcontext(&old_ctx->uc_mcontext, current, 0, NULL, 0,
670
665
 					ctx_has_vsx_region)
671
666
 		    || __copy_to_user(&old_ctx->uc_sigmask,
..
..
@@ -674,9 +669,8 @@
674
669
 	}
675
670
 	if (new_ctx == NULL)
676
671
 		return 0;
677
-	if (!access_ok(VERIFY_READ, new_ctx, ctx_size)
678
-	    || __get_user(tmp, (u8 __user *) new_ctx)
679
-	    || __get_user(tmp, (u8 __user *) new_ctx + ctx_size - 1))
672
+	if (!access_ok(new_ctx, ctx_size) ||
673
+	    fault_in_pages_readable((u8 __user *)new_ctx, ctx_size))
680
674
 		return -EFAULT;
681
675
 
682
676
 	/*
..
..
@@ -719,7 +713,7 @@
719
713
 	/* Always make any pending restarted system calls return -EINTR */
720
714
 	current->restart_block.fn = do_no_restart_syscall;
721
715
 
722
-	if (!access_ok(VERIFY_READ, uc, sizeof(*uc)))
716
+	if (!access_ok(uc, sizeof(*uc)))
723
717
 		goto badframe;
724
718
 
725
719
 	if (__copy_from_user(&set, &uc->uc_sigmask, sizeof(set)))
..
..
@@ -739,6 +733,31 @@
739
733
 	 */
740
734
 	if (MSR_TM_SUSPENDED(mfmsr()))
741
735
 		tm_reclaim_current(0);
736
+
737
+	/*
738
+	 * Disable MSR[TS] bit also, so, if there is an exception in the
739
+	 * code below (as a page fault in copy_ckvsx_to_user()), it does
740
+	 * not recheckpoint this task if there was a context switch inside
741
+	 * the exception.
742
+	 *
743
+	 * A major page fault can indirectly call schedule(). A reschedule
744
+	 * process in the middle of an exception can have a side effect
745
+	 * (Changing the CPU MSR[TS] state), since schedule() is called
746
+	 * with the CPU MSR[TS] disable and returns with MSR[TS]=Suspended
747
+	 * (switch_to() calls tm_recheckpoint() for the 'new' process). In
748
+	 * this case, the process continues to be the same in the CPU, but
749
+	 * the CPU state just changed.
750
+	 *
751
+	 * This can cause a TM Bad Thing, since the MSR in the stack will
752
+	 * have the MSR[TS]=0, and this is what will be used to RFID.
753
+	 *
754
+	 * Clearing MSR[TS] state here will avoid a recheckpoint if there
755
+	 * is any process reschedule in kernel space. The MSR[TS] state
756
+	 * does not need to be saved also, since it will be replaced with
757
+	 * the MSR[TS] that came from user context later, at
758
+	 * restore_tm_sigcontexts.
759
+	 */
760
+	regs->msr &= ~MSR_TS_MASK;
742
761
 
743
762
 	if (__get_user(msr, &uc->uc_mcontext.gp_regs[PT_MSR]))
744
763
 		goto badframe;
..
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@@ -787,7 +806,7 @@
787
806
 				   current->comm, current->pid, "rt_sigreturn",
788
807
 				   (long)uc, regs->nip, regs->link);
789
808
 
790
-	force_sig(SIGSEGV, current);
809
+	force_sig(SIGSEGV);
791
810
 	return 0;
792
811
 }
793
812
 
..
..
@@ -846,12 +865,12 @@
846
865
 
847
866
 	/* Set up to return from userspace. */
848
867
 	if (vdso64_rt_sigtramp && tsk->mm->context.vdso_base) {
849
-		regs->link = tsk->mm->context.vdso_base + vdso64_rt_sigtramp;
868
+		regs->nip = tsk->mm->context.vdso_base + vdso64_rt_sigtramp;
850
869
 	} else {
851
870
 		err |= setup_trampoline(__NR_rt_sigreturn, &frame->tramp[0]);
852
871
 		if (err)
853
872
 			goto badframe;
854
-		regs->link = (unsigned long) &frame->tramp[0];
873
+		regs->nip = (unsigned long) &frame->tramp[0];
855
874
 	}
856
875
 
857
876
 	/* Allocate a dummy caller frame for the signal handler. */
..
..
@@ -860,8 +879,8 @@
860
879
 
861
880
 	/* Set up "regs" so we "return" to the signal handler. */
862
881
 	if (is_elf2_task()) {
863
-		regs->nip = (unsigned long) ksig->ka.sa.sa_handler;
864
-		regs->gpr[12] = regs->nip;
882
+		regs->ctr = (unsigned long) ksig->ka.sa.sa_handler;
883
+		regs->gpr[12] = regs->ctr;
865
884
 	} else {
866
885
 		/* Handler is *really* a pointer to the function descriptor for
867
886
 		 * the signal routine.  The first entry in the function
..
..
@@ -871,7 +890,7 @@
871
890
 		func_descr_t __user *funct_desc_ptr =
872
891
 			(func_descr_t __user *) ksig->ka.sa.sa_handler;
873
892
 
874
-		err |= get_user(regs->nip, &funct_desc_ptr->entry);
893
+		err |= get_user(regs->ctr, &funct_desc_ptr->entry);
875
894
 		err |= get_user(regs->gpr[2], &funct_desc_ptr->toc);
876
895
 	}
877
896