96d4f267e4
Nobody has actually used the type (VERIFY_READ vs VERIFY_WRITE) argument
of the user address range verification function since we got rid of the
old racy i386-only code to walk page tables by hand.
It existed because the original 80386 would not honor the write protect
bit when in kernel mode, so you had to do COW by hand before doing any
user access. But we haven't supported that in a long time, and these
days the 'type' argument is a purely historical artifact.
A discussion about extending 'user_access_begin()' to do the range
checking resulted this patch, because there is no way we're going to
move the old VERIFY_xyz interface to that model. And it's best done at
the end of the merge window when I've done most of my merges, so let's
just get this done once and for all.
This patch was mostly done with a sed-script, with manual fix-ups for
the cases that weren't of the trivial 'access_ok(VERIFY_xyz' form.
There were a couple of notable cases:
- csky still had the old "verify_area()" name as an alias.
- the iter_iov code had magical hardcoded knowledge of the actual
values of VERIFY_{READ,WRITE} (not that they mattered, since nothing
really used it)
- microblaze used the type argument for a debug printout
but other than those oddities this should be a total no-op patch.
I tried to fix up all architectures, did fairly extensive grepping for
access_ok() uses, and the changes are trivial, but I may have missed
something. Any missed conversion should be trivially fixable, though.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
403 lines
11 KiB
C
403 lines
11 KiB
C
/*
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* Signal Handling for ARC
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*
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* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* vineetg: Jan 2010 (Restarting of timer related syscalls)
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*
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* vineetg: Nov 2009 (Everything needed for TIF_RESTORE_SIGMASK)
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* -do_signal() supports TIF_RESTORE_SIGMASK
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* -do_signal() no loner needs oldset, required by OLD sys_sigsuspend
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* -sys_rt_sigsuspend() now comes from generic code, so discard arch implemen
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* -sys_sigsuspend() no longer needs to fudge ptregs, hence that arg removed
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* -sys_sigsuspend() no longer loops for do_signal(), sets TIF_xxx and leaves
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* the job to do_signal()
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*
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* vineetg: July 2009
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* -Modified Code to support the uClibc provided userland sigreturn stub
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* to avoid kernel synthesing it on user stack at runtime, costing TLB
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* probes and Cache line flushes.
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*
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* vineetg: July 2009
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* -In stash_usr_regs( ) and restore_usr_regs( ), save/restore of user regs
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* in done in block copy rather than one word at a time.
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* This saves around 2K of code and improves LMBench lat_sig <catch>
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*
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* rajeshwarr: Feb 2009
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* - Support for Realtime Signals
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*
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* vineetg: Aug 11th 2008: Bug #94183
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* -ViXS were still seeing crashes when using insmod to load drivers.
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* It turned out that the code to change Execute permssions for TLB entries
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* of user was not guarded for interrupts (mod_tlb_permission)
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* This was causing TLB entries to be overwritten on unrelated indexes
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*
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* Vineetg: July 15th 2008: Bug #94183
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* -Exception happens in Delay slot of a JMP, and before user space resumes,
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* Signal is delivered (Ctrl + C) = >SIGINT.
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* setup_frame( ) sets up PC,SP,BLINK to enable user space signal handler
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* to run, but doesn't clear the Delay slot bit from status32. As a result,
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* on resuming user mode, signal handler branches off to BTA of orig JMP
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* -FIX: clear the DE bit from status32 in setup_frame( )
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*
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* Rahul Trivedi, Kanika Nema: Codito Technologies 2004
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*/
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#include <linux/signal.h>
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#include <linux/ptrace.h>
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#include <linux/personality.h>
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#include <linux/uaccess.h>
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#include <linux/syscalls.h>
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#include <linux/tracehook.h>
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#include <linux/sched/task_stack.h>
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#include <asm/ucontext.h>
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struct rt_sigframe {
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struct siginfo info;
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struct ucontext uc;
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#define MAGIC_SIGALTSTK 0x07302004
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unsigned int sigret_magic;
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};
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static int
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stash_usr_regs(struct rt_sigframe __user *sf, struct pt_regs *regs,
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sigset_t *set)
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{
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int err;
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struct user_regs_struct uregs;
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uregs.scratch.bta = regs->bta;
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uregs.scratch.lp_start = regs->lp_start;
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uregs.scratch.lp_end = regs->lp_end;
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uregs.scratch.lp_count = regs->lp_count;
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uregs.scratch.status32 = regs->status32;
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uregs.scratch.ret = regs->ret;
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uregs.scratch.blink = regs->blink;
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uregs.scratch.fp = regs->fp;
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uregs.scratch.gp = regs->r26;
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uregs.scratch.r12 = regs->r12;
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uregs.scratch.r11 = regs->r11;
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uregs.scratch.r10 = regs->r10;
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uregs.scratch.r9 = regs->r9;
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uregs.scratch.r8 = regs->r8;
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uregs.scratch.r7 = regs->r7;
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uregs.scratch.r6 = regs->r6;
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uregs.scratch.r5 = regs->r5;
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uregs.scratch.r4 = regs->r4;
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uregs.scratch.r3 = regs->r3;
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uregs.scratch.r2 = regs->r2;
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uregs.scratch.r1 = regs->r1;
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uregs.scratch.r0 = regs->r0;
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uregs.scratch.sp = regs->sp;
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err = __copy_to_user(&(sf->uc.uc_mcontext.regs.scratch), &uregs.scratch,
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sizeof(sf->uc.uc_mcontext.regs.scratch));
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err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(sigset_t));
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return err;
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}
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static int restore_usr_regs(struct pt_regs *regs, struct rt_sigframe __user *sf)
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{
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sigset_t set;
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int err;
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struct user_regs_struct uregs;
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err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
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err |= __copy_from_user(&uregs.scratch,
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&(sf->uc.uc_mcontext.regs.scratch),
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sizeof(sf->uc.uc_mcontext.regs.scratch));
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if (err)
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return err;
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set_current_blocked(&set);
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regs->bta = uregs.scratch.bta;
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regs->lp_start = uregs.scratch.lp_start;
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regs->lp_end = uregs.scratch.lp_end;
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regs->lp_count = uregs.scratch.lp_count;
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regs->status32 = uregs.scratch.status32;
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regs->ret = uregs.scratch.ret;
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regs->blink = uregs.scratch.blink;
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regs->fp = uregs.scratch.fp;
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regs->r26 = uregs.scratch.gp;
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regs->r12 = uregs.scratch.r12;
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regs->r11 = uregs.scratch.r11;
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regs->r10 = uregs.scratch.r10;
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regs->r9 = uregs.scratch.r9;
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regs->r8 = uregs.scratch.r8;
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regs->r7 = uregs.scratch.r7;
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regs->r6 = uregs.scratch.r6;
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regs->r5 = uregs.scratch.r5;
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regs->r4 = uregs.scratch.r4;
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regs->r3 = uregs.scratch.r3;
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regs->r2 = uregs.scratch.r2;
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regs->r1 = uregs.scratch.r1;
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regs->r0 = uregs.scratch.r0;
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regs->sp = uregs.scratch.sp;
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return 0;
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}
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static inline int is_do_ss_needed(unsigned int magic)
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{
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if (MAGIC_SIGALTSTK == magic)
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return 1;
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else
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return 0;
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}
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SYSCALL_DEFINE0(rt_sigreturn)
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{
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struct rt_sigframe __user *sf;
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unsigned int magic;
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struct pt_regs *regs = current_pt_regs();
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/* Always make any pending restarted system calls return -EINTR */
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current->restart_block.fn = do_no_restart_syscall;
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/* Since we stacked the signal on a word boundary,
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* then 'sp' should be word aligned here. If it's
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* not, then the user is trying to mess with us.
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*/
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if (regs->sp & 3)
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goto badframe;
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sf = (struct rt_sigframe __force __user *)(regs->sp);
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if (!access_ok(sf, sizeof(*sf)))
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goto badframe;
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if (__get_user(magic, &sf->sigret_magic))
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goto badframe;
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if (unlikely(is_do_ss_needed(magic)))
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if (restore_altstack(&sf->uc.uc_stack))
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goto badframe;
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if (restore_usr_regs(regs, sf))
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goto badframe;
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/* Don't restart from sigreturn */
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syscall_wont_restart(regs);
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/*
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* Ensure that sigreturn always returns to user mode (in case the
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* regs saved on user stack got fudged between save and sigreturn)
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* Otherwise it is easy to panic the kernel with a custom
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* signal handler and/or restorer which clobberes the status32/ret
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* to return to a bogus location in kernel mode.
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*/
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regs->status32 |= STATUS_U_MASK;
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return regs->r0;
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badframe:
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force_sig(SIGSEGV, current);
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return 0;
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}
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/*
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* Determine which stack to use..
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*/
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static inline void __user *get_sigframe(struct ksignal *ksig,
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struct pt_regs *regs,
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unsigned long framesize)
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{
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unsigned long sp = sigsp(regs->sp, ksig);
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void __user *frame;
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/* No matter what happens, 'sp' must be word
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* aligned otherwise nasty things could happen
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*/
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/* ATPCS B01 mandates 8-byte alignment */
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frame = (void __user *)((sp - framesize) & ~7);
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/* Check that we can actually write to the signal frame */
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if (!access_ok(frame, framesize))
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frame = NULL;
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return frame;
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}
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static int
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setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
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{
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struct rt_sigframe __user *sf;
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unsigned int magic = 0;
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int err = 0;
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sf = get_sigframe(ksig, regs, sizeof(struct rt_sigframe));
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if (!sf)
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return 1;
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/*
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* w/o SA_SIGINFO, struct ucontext is partially populated (only
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* uc_mcontext/uc_sigmask) for kernel's normal user state preservation
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* during signal handler execution. This works for SA_SIGINFO as well
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* although the semantics are now overloaded (the same reg state can be
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* inspected by userland: but are they allowed to fiddle with it ?
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*/
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err |= stash_usr_regs(sf, regs, set);
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/*
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* SA_SIGINFO requires 3 args to signal handler:
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* #1: sig-no (common to any handler)
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* #2: struct siginfo
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* #3: struct ucontext (completely populated)
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*/
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if (unlikely(ksig->ka.sa.sa_flags & SA_SIGINFO)) {
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err |= copy_siginfo_to_user(&sf->info, &ksig->info);
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err |= __put_user(0, &sf->uc.uc_flags);
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err |= __put_user(NULL, &sf->uc.uc_link);
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err |= __save_altstack(&sf->uc.uc_stack, regs->sp);
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/* setup args 2 and 3 for user mode handler */
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regs->r1 = (unsigned long)&sf->info;
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regs->r2 = (unsigned long)&sf->uc;
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/*
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* small optim to avoid unconditonally calling do_sigaltstack
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* in sigreturn path, now that we only have rt_sigreturn
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*/
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magic = MAGIC_SIGALTSTK;
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}
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err |= __put_user(magic, &sf->sigret_magic);
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if (err)
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return err;
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/* #1 arg to the user Signal handler */
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regs->r0 = ksig->sig;
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/* setup PC of user space signal handler */
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regs->ret = (unsigned long)ksig->ka.sa.sa_handler;
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/*
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* handler returns using sigreturn stub provided already by userpsace
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* If not, nuke the process right away
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*/
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if(!(ksig->ka.sa.sa_flags & SA_RESTORER))
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return 1;
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regs->blink = (unsigned long)ksig->ka.sa.sa_restorer;
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/* User Stack for signal handler will be above the frame just carved */
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regs->sp = (unsigned long)sf;
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/*
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* Bug 94183, Clear the DE bit, so that when signal handler
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* starts to run, it doesn't use BTA
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*/
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regs->status32 &= ~STATUS_DE_MASK;
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regs->status32 |= STATUS_L_MASK;
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return err;
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}
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static void arc_restart_syscall(struct k_sigaction *ka, struct pt_regs *regs)
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{
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switch (regs->r0) {
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case -ERESTART_RESTARTBLOCK:
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case -ERESTARTNOHAND:
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/*
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* ERESTARTNOHAND means that the syscall should
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* only be restarted if there was no handler for
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* the signal, and since we only get here if there
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* is a handler, we don't restart
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*/
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regs->r0 = -EINTR; /* ERESTART_xxx is internal */
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break;
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case -ERESTARTSYS:
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/*
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* ERESTARTSYS means to restart the syscall if
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* there is no handler or the handler was
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* registered with SA_RESTART
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*/
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if (!(ka->sa.sa_flags & SA_RESTART)) {
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regs->r0 = -EINTR;
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break;
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}
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/* fallthrough */
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case -ERESTARTNOINTR:
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/*
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* ERESTARTNOINTR means that the syscall should
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* be called again after the signal handler returns.
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* Setup reg state just as it was before doing the trap
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* r0 has been clobbered with sys call ret code thus it
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* needs to be reloaded with orig first arg to syscall
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* in orig_r0. Rest of relevant reg-file:
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* r8 (syscall num) and (r1 - r7) will be reset to
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* their orig user space value when we ret from kernel
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*/
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regs->r0 = regs->orig_r0;
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regs->ret -= is_isa_arcv2() ? 2 : 4;
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break;
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}
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}
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/*
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* OK, we're invoking a handler
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*/
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static void
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handle_signal(struct ksignal *ksig, struct pt_regs *regs)
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{
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sigset_t *oldset = sigmask_to_save();
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int failed;
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/* Set up the stack frame */
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failed = setup_rt_frame(ksig, oldset, regs);
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signal_setup_done(failed, ksig, 0);
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}
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void do_signal(struct pt_regs *regs)
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{
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struct ksignal ksig;
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int restart_scall;
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restart_scall = in_syscall(regs) && syscall_restartable(regs);
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if (get_signal(&ksig)) {
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if (restart_scall) {
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arc_restart_syscall(&ksig.ka, regs);
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syscall_wont_restart(regs); /* No more restarts */
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}
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handle_signal(&ksig, regs);
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return;
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}
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if (restart_scall) {
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/* No handler for syscall: restart it */
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if (regs->r0 == -ERESTARTNOHAND ||
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regs->r0 == -ERESTARTSYS || regs->r0 == -ERESTARTNOINTR) {
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regs->r0 = regs->orig_r0;
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regs->ret -= is_isa_arcv2() ? 2 : 4;
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} else if (regs->r0 == -ERESTART_RESTARTBLOCK) {
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regs->r8 = __NR_restart_syscall;
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regs->ret -= is_isa_arcv2() ? 2 : 4;
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}
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syscall_wont_restart(regs); /* No more restarts */
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}
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/* If there's no signal to deliver, restore the saved sigmask back */
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restore_saved_sigmask();
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}
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void do_notify_resume(struct pt_regs *regs)
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{
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/*
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* ASM glue gaurantees that this is only called when returning to
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* user mode
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*/
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if (test_and_clear_thread_flag(TIF_NOTIFY_RESUME))
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tracehook_notify_resume(regs);
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}
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