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kernel-ark/arch/powerpc/kernel/signal_64.c
Michael Neuling 2b3f8e87cf powerpc/tm: Fix userspace stack corruption on signal delivery for active transactions 
When in an active transaction that takes a signal, we need to be careful with
the stack.  It's possible that the stack has moved back up after the tbegin.
The obvious case here is when the tbegin is called inside a function that
returns before a tend.  In this case, the stack is part of the checkpointed
transactional memory state.  If we write over this non transactionally or in
suspend, we are in trouble because if we get a tm abort, the program counter
and stack pointer will be back at the tbegin but our in memory stack won't be
valid anymore.

To avoid this, when taking a signal in an active transaction, we need to use
the stack pointer from the checkpointed state, rather than the speculated
state.  This ensures that the signal context (written tm suspended) will be
written below the stack required for the rollback.  The transaction is aborted
becuase of the treclaim, so any memory written between the tbegin and the
signal will be rolled back anyway.

For signals taken in non-TM or suspended mode, we use the
normal/non-checkpointed stack pointer.

Tested with 64 and 32 bit signals

Signed-off-by: Michael Neuling <mikey@neuling.org>
Cc: <stable@vger.kernel.org> # v3.9
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2013-06-01 08:29:23 +10:00

799 lines
25 KiB
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/*
* PowerPC version
* Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
*
* Derived from "arch/i386/kernel/signal.c"
* Copyright (C) 1991, 1992 Linus Torvalds
* 1997-11-28 Modified for POSIX.1b signals by Richard Henderson
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/errno.h>
#include <linux/wait.h>
#include <linux/unistd.h>
#include <linux/stddef.h>
#include <linux/elf.h>
#include <linux/ptrace.h>
#include <linux/ratelimit.h>
#include <asm/sigcontext.h>
#include <asm/ucontext.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/unistd.h>
#include <asm/cacheflush.h>
#include <asm/syscalls.h>
#include <asm/vdso.h>
#include <asm/switch_to.h>
#include <asm/tm.h>
#include "signal.h"
#define DEBUG_SIG 0
#define GP_REGS_SIZE min(sizeof(elf_gregset_t), sizeof(struct pt_regs))
#define FP_REGS_SIZE sizeof(elf_fpregset_t)
#define TRAMP_TRACEBACK 3
#define TRAMP_SIZE 6
/*
* When we have signals to deliver, we set up on the user stack,
* going down from the original stack pointer:
* 1) a rt_sigframe struct which contains the ucontext
* 2) a gap of __SIGNAL_FRAMESIZE bytes which acts as a dummy caller
* frame for the signal handler.
*/
struct rt_sigframe {
/* sys_rt_sigreturn requires the ucontext be the first field */
struct ucontext uc;
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
struct ucontext uc_transact;
#endif
unsigned long _unused[2];
unsigned int tramp[TRAMP_SIZE];
struct siginfo __user *pinfo;
void __user *puc;
struct siginfo info;
/* 64 bit ABI allows for 288 bytes below sp before decrementing it. */
char abigap[288];
} __attribute__ ((aligned (16)));
static const char fmt32[] = KERN_INFO \
"%s[%d]: bad frame in %s: %08lx nip %08lx lr %08lx\n";
static const char fmt64[] = KERN_INFO \
"%s[%d]: bad frame in %s: %016lx nip %016lx lr %016lx\n";
/*
* Set up the sigcontext for the signal frame.
*/
static long setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
int signr, sigset_t *set, unsigned long handler,
int ctx_has_vsx_region)
{
/* When CONFIG_ALTIVEC is set, we _always_ setup v_regs even if the
* process never used altivec yet (MSR_VEC is zero in pt_regs of
* the context). This is very important because we must ensure we
* don't lose the VRSAVE content that may have been set prior to
* the process doing its first vector operation
* Userland shall check AT_HWCAP to know whether it can rely on the
* v_regs pointer or not
*/
#ifdef CONFIG_ALTIVEC
elf_vrreg_t __user *v_regs = (elf_vrreg_t __user *)(((unsigned long)sc->vmx_reserve + 15) & ~0xful);
#endif
unsigned long msr = regs->msr;
long err = 0;
flush_fp_to_thread(current);
#ifdef CONFIG_ALTIVEC
err |= __put_user(v_regs, &sc->v_regs);
/* save altivec registers */
if (current->thread.used_vr) {
flush_altivec_to_thread(current);
/* Copy 33 vec registers (vr0..31 and vscr) to the stack */
err |= __copy_to_user(v_regs, current->thread.vr, 33 * sizeof(vector128));
/* set MSR_VEC in the MSR value in the frame to indicate that sc->v_reg)
* contains valid data.
*/
msr |= MSR_VEC;
}
/* We always copy to/from vrsave, it's 0 if we don't have or don't
* use altivec.
*/
err |= __put_user(current->thread.vrsave, (u32 __user *)&v_regs[33]);
#else /* CONFIG_ALTIVEC */
err |= __put_user(0, &sc->v_regs);
#endif /* CONFIG_ALTIVEC */
flush_fp_to_thread(current);
/* copy fpr regs and fpscr */
err |= copy_fpr_to_user(&sc->fp_regs, current);
#ifdef CONFIG_VSX
/*
* Copy VSX low doubleword to local buffer for formatting,
* then out to userspace. Update v_regs to point after the
* VMX data.
*/
if (current->thread.used_vsr && ctx_has_vsx_region) {
__giveup_vsx(current);
v_regs += ELF_NVRREG;
err |= copy_vsx_to_user(v_regs, current);
/* set MSR_VSX in the MSR value in the frame to
* indicate that sc->vs_reg) contains valid data.
*/
msr |= MSR_VSX;
}
#endif /* CONFIG_VSX */
err |= __put_user(&sc->gp_regs, &sc->regs);
WARN_ON(!FULL_REGS(regs));
err |= __copy_to_user(&sc->gp_regs, regs, GP_REGS_SIZE);
err |= __put_user(msr, &sc->gp_regs[PT_MSR]);
err |= __put_user(signr, &sc->signal);
err |= __put_user(handler, &sc->handler);
if (set != NULL)
err |= __put_user(set->sig[0], &sc->oldmask);
return err;
}
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
/*
* As above, but Transactional Memory is in use, so deliver sigcontexts
* containing checkpointed and transactional register states.
*
* To do this, we treclaim (done before entering here) to gather both sets of
* registers and set up the 'normal' sigcontext registers with rolled-back
* register values such that a simple signal handler sees a correct
* checkpointed register state. If interested, a TM-aware sighandler can
* examine the transactional registers in the 2nd sigcontext to determine the
* real origin of the signal.
*/
static long setup_tm_sigcontexts(struct sigcontext __user *sc,
struct sigcontext __user *tm_sc,
struct pt_regs *regs,
int signr, sigset_t *set, unsigned long handler)
{
/* When CONFIG_ALTIVEC is set, we _always_ setup v_regs even if the
* process never used altivec yet (MSR_VEC is zero in pt_regs of
* the context). This is very important because we must ensure we
* don't lose the VRSAVE content that may have been set prior to
* the process doing its first vector operation
* Userland shall check AT_HWCAP to know wether it can rely on the
* v_regs pointer or not.
*/
#ifdef CONFIG_ALTIVEC
elf_vrreg_t __user *v_regs = (elf_vrreg_t __user *)
(((unsigned long)sc->vmx_reserve + 15) & ~0xful);
elf_vrreg_t __user *tm_v_regs = (elf_vrreg_t __user *)
(((unsigned long)tm_sc->vmx_reserve + 15) & ~0xful);
#endif
unsigned long msr = regs->msr;
long err = 0;
BUG_ON(!MSR_TM_ACTIVE(regs->msr));
flush_fp_to_thread(current);
#ifdef CONFIG_ALTIVEC
err |= __put_user(v_regs, &sc->v_regs);
err |= __put_user(tm_v_regs, &tm_sc->v_regs);
/* save altivec registers */
if (current->thread.used_vr) {
flush_altivec_to_thread(current);
/* Copy 33 vec registers (vr0..31 and vscr) to the stack */
err |= __copy_to_user(v_regs, current->thread.vr,
33 * sizeof(vector128));
/* If VEC was enabled there are transactional VRs valid too,
* else they're a copy of the checkpointed VRs.
*/
if (msr & MSR_VEC)
err |= __copy_to_user(tm_v_regs,
current->thread.transact_vr,
33 * sizeof(vector128));
else
err |= __copy_to_user(tm_v_regs,
current->thread.vr,
33 * sizeof(vector128));
/* set MSR_VEC in the MSR value in the frame to indicate
* that sc->v_reg contains valid data.
*/
msr |= MSR_VEC;
}
/* We always copy to/from vrsave, it's 0 if we don't have or don't
* use altivec.
*/
err |= __put_user(current->thread.vrsave, (u32 __user *)&v_regs[33]);
if (msr & MSR_VEC)
err |= __put_user(current->thread.transact_vrsave,
(u32 __user *)&tm_v_regs[33]);
else
err |= __put_user(current->thread.vrsave,
(u32 __user *)&tm_v_regs[33]);
#else /* CONFIG_ALTIVEC */
err |= __put_user(0, &sc->v_regs);
err |= __put_user(0, &tm_sc->v_regs);
#endif /* CONFIG_ALTIVEC */
/* copy fpr regs and fpscr */
err |= copy_fpr_to_user(&sc->fp_regs, current);
if (msr & MSR_FP)
err |= copy_transact_fpr_to_user(&tm_sc->fp_regs, current);
else
err |= copy_fpr_to_user(&tm_sc->fp_regs, current);
#ifdef CONFIG_VSX
/*
* Copy VSX low doubleword to local buffer for formatting,
* then out to userspace. Update v_regs to point after the
* VMX data.
*/
if (current->thread.used_vsr) {
__giveup_vsx(current);
v_regs += ELF_NVRREG;
tm_v_regs += ELF_NVRREG;
err |= copy_vsx_to_user(v_regs, current);
if (msr & MSR_VSX)
err |= copy_transact_vsx_to_user(tm_v_regs, current);
else
err |= copy_vsx_to_user(tm_v_regs, current);
/* set MSR_VSX in the MSR value in the frame to
* indicate that sc->vs_reg) contains valid data.
*/
msr |= MSR_VSX;
}
#endif /* CONFIG_VSX */
err |= __put_user(&sc->gp_regs, &sc->regs);
err |= __put_user(&tm_sc->gp_regs, &tm_sc->regs);
WARN_ON(!FULL_REGS(regs));
err |= __copy_to_user(&tm_sc->gp_regs, regs, GP_REGS_SIZE);
err |= __copy_to_user(&sc->gp_regs,
&current->thread.ckpt_regs, GP_REGS_SIZE);
err |= __put_user(msr, &tm_sc->gp_regs[PT_MSR]);
err |= __put_user(msr, &sc->gp_regs[PT_MSR]);
err |= __put_user(signr, &sc->signal);
err |= __put_user(handler, &sc->handler);
if (set != NULL)
err |= __put_user(set->sig[0], &sc->oldmask);
return err;
}
#endif
/*
* Restore the sigcontext from the signal frame.
*/
static long restore_sigcontext(struct pt_regs *regs, sigset_t *set, int sig,
struct sigcontext __user *sc)
{
#ifdef CONFIG_ALTIVEC
elf_vrreg_t __user *v_regs;
#endif
unsigned long err = 0;
unsigned long save_r13 = 0;
unsigned long msr;
#ifdef CONFIG_VSX
int i;
#endif
/* If this is not a signal return, we preserve the TLS in r13 */
if (!sig)
save_r13 = regs->gpr[13];
/* copy the GPRs */
err |= __copy_from_user(regs->gpr, sc->gp_regs, sizeof(regs->gpr));
err |= __get_user(regs->nip, &sc->gp_regs[PT_NIP]);
/* get MSR separately, transfer the LE bit if doing signal return */
err |= __get_user(msr, &sc->gp_regs[PT_MSR]);
if (sig)
regs->msr = (regs->msr & ~MSR_LE) | (msr & MSR_LE);
err |= __get_user(regs->orig_gpr3, &sc->gp_regs[PT_ORIG_R3]);
err |= __get_user(regs->ctr, &sc->gp_regs[PT_CTR]);
err |= __get_user(regs->link, &sc->gp_regs[PT_LNK]);
err |= __get_user(regs->xer, &sc->gp_regs[PT_XER]);
err |= __get_user(regs->ccr, &sc->gp_regs[PT_CCR]);
/* skip SOFTE */
regs->trap = 0;
err |= __get_user(regs->dar, &sc->gp_regs[PT_DAR]);
err |= __get_user(regs->dsisr, &sc->gp_regs[PT_DSISR]);
err |= __get_user(regs->result, &sc->gp_regs[PT_RESULT]);
if (!sig)
regs->gpr[13] = save_r13;
if (set != NULL)
err |= __get_user(set->sig[0], &sc->oldmask);
/*
* Do this before updating the thread state in
* current->thread.fpr/vr. That way, if we get preempted
* and another task grabs the FPU/Altivec, it won't be
* tempted to save the current CPU state into the thread_struct
* and corrupt what we are writing there.
*/
discard_lazy_cpu_state();
/*
* Force reload of FP/VEC.
* This has to be done before copying stuff into current->thread.fpr/vr
* for the reasons explained in the previous comment.
*/
regs->msr &= ~(MSR_FP | MSR_FE0 | MSR_FE1 | MSR_VEC | MSR_VSX);
#ifdef CONFIG_ALTIVEC
err |= __get_user(v_regs, &sc->v_regs);
if (err)
return err;
if (v_regs && !access_ok(VERIFY_READ, v_regs, 34 * sizeof(vector128)))
return -EFAULT;
/* Copy 33 vec registers (vr0..31 and vscr) from the stack */
if (v_regs != 0 && (msr & MSR_VEC) != 0)
err |= __copy_from_user(current->thread.vr, v_regs,
33 * sizeof(vector128));
else if (current->thread.used_vr)
memset(current->thread.vr, 0, 33 * sizeof(vector128));
/* Always get VRSAVE back */
if (v_regs != 0)
err |= __get_user(current->thread.vrsave, (u32 __user *)&v_regs[33]);
else
current->thread.vrsave = 0;
#endif /* CONFIG_ALTIVEC */
/* restore floating point */
err |= copy_fpr_from_user(current, &sc->fp_regs);
#ifdef CONFIG_VSX
/*
* Get additional VSX data. Update v_regs to point after the
* VMX data. Copy VSX low doubleword from userspace to local
* buffer for formatting, then into the taskstruct.
*/
v_regs += ELF_NVRREG;
if ((msr & MSR_VSX) != 0)
err |= copy_vsx_from_user(current, v_regs);
else
for (i = 0; i < 32 ; i++)
current->thread.fpr[i][TS_VSRLOWOFFSET] = 0;
#endif
return err;
}
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
/*
* Restore the two sigcontexts from the frame of a transactional processes.
*/
static long restore_tm_sigcontexts(struct pt_regs *regs,
struct sigcontext __user *sc,
struct sigcontext __user *tm_sc)
{
#ifdef CONFIG_ALTIVEC
elf_vrreg_t __user *v_regs, *tm_v_regs;
#endif
unsigned long err = 0;
unsigned long msr;
#ifdef CONFIG_VSX
int i;
#endif
/* copy the GPRs */
err |= __copy_from_user(regs->gpr, tm_sc->gp_regs, sizeof(regs->gpr));
err |= __copy_from_user(&current->thread.ckpt_regs, sc->gp_regs,
sizeof(regs->gpr));
/*
* TFHAR is restored from the checkpointed 'wound-back' ucontext's NIP.
* TEXASR was set by the signal delivery reclaim, as was TFIAR.
* Users doing anything abhorrent like thread-switching w/ signals for
* TM-Suspended code will have to back TEXASR/TFIAR up themselves.
* For the case of getting a signal and simply returning from it,
* we don't need to re-copy them here.
*/
err |= __get_user(regs->nip, &tm_sc->gp_regs[PT_NIP]);
err |= __get_user(current->thread.tm_tfhar, &sc->gp_regs[PT_NIP]);
/* get MSR separately, transfer the LE bit if doing signal return */
err |= __get_user(msr, &sc->gp_regs[PT_MSR]);
regs->msr = (regs->msr & ~MSR_LE) | (msr & MSR_LE);
/* The following non-GPR non-FPR non-VR state is also checkpointed: */
err |= __get_user(regs->ctr, &tm_sc->gp_regs[PT_CTR]);
err |= __get_user(regs->link, &tm_sc->gp_regs[PT_LNK]);
err |= __get_user(regs->xer, &tm_sc->gp_regs[PT_XER]);
err |= __get_user(regs->ccr, &tm_sc->gp_regs[PT_CCR]);
err |= __get_user(current->thread.ckpt_regs.ctr,
&sc->gp_regs[PT_CTR]);
err |= __get_user(current->thread.ckpt_regs.link,
&sc->gp_regs[PT_LNK]);
err |= __get_user(current->thread.ckpt_regs.xer,
&sc->gp_regs[PT_XER]);
err |= __get_user(current->thread.ckpt_regs.ccr,
&sc->gp_regs[PT_CCR]);
/* These regs are not checkpointed; they can go in 'regs'. */
err |= __get_user(regs->trap, &sc->gp_regs[PT_TRAP]);
err |= __get_user(regs->dar, &sc->gp_regs[PT_DAR]);
err |= __get_user(regs->dsisr, &sc->gp_regs[PT_DSISR]);
err |= __get_user(regs->result, &sc->gp_regs[PT_RESULT]);
/*
* Do this before updating the thread state in
* current->thread.fpr/vr. That way, if we get preempted
* and another task grabs the FPU/Altivec, it won't be
* tempted to save the current CPU state into the thread_struct
* and corrupt what we are writing there.
*/
discard_lazy_cpu_state();
/*
* Force reload of FP/VEC.
* This has to be done before copying stuff into current->thread.fpr/vr
* for the reasons explained in the previous comment.
*/
regs->msr &= ~(MSR_FP | MSR_FE0 | MSR_FE1 | MSR_VEC | MSR_VSX);
#ifdef CONFIG_ALTIVEC
err |= __get_user(v_regs, &sc->v_regs);
err |= __get_user(tm_v_regs, &tm_sc->v_regs);
if (err)
return err;
if (v_regs && !access_ok(VERIFY_READ, v_regs, 34 * sizeof(vector128)))
return -EFAULT;
if (tm_v_regs && !access_ok(VERIFY_READ,
tm_v_regs, 34 * sizeof(vector128)))
return -EFAULT;
/* Copy 33 vec registers (vr0..31 and vscr) from the stack */
if (v_regs != 0 && tm_v_regs != 0 && (msr & MSR_VEC) != 0) {
err |= __copy_from_user(current->thread.vr, v_regs,
33 * sizeof(vector128));
err |= __copy_from_user(current->thread.transact_vr, tm_v_regs,
33 * sizeof(vector128));
}
else if (current->thread.used_vr) {
memset(current->thread.vr, 0, 33 * sizeof(vector128));
memset(current->thread.transact_vr, 0, 33 * sizeof(vector128));
}
/* Always get VRSAVE back */
if (v_regs != 0 && tm_v_regs != 0) {
err |= __get_user(current->thread.vrsave,
(u32 __user *)&v_regs[33]);
err |= __get_user(current->thread.transact_vrsave,
(u32 __user *)&tm_v_regs[33]);
}
else {
current->thread.vrsave = 0;
current->thread.transact_vrsave = 0;
}
#endif /* CONFIG_ALTIVEC */
/* restore floating point */
err |= copy_fpr_from_user(current, &sc->fp_regs);
err |= copy_transact_fpr_from_user(current, &tm_sc->fp_regs);
#ifdef CONFIG_VSX
/*
* Get additional VSX data. Update v_regs to point after the
* VMX data. Copy VSX low doubleword from userspace to local
* buffer for formatting, then into the taskstruct.
*/
if (v_regs && ((msr & MSR_VSX) != 0)) {
v_regs += ELF_NVRREG;
tm_v_regs += ELF_NVRREG;
err |= copy_vsx_from_user(current, v_regs);
err |= copy_transact_vsx_from_user(current, tm_v_regs);
} else {
for (i = 0; i < 32 ; i++) {
current->thread.fpr[i][TS_VSRLOWOFFSET] = 0;
current->thread.transact_fpr[i][TS_VSRLOWOFFSET] = 0;
}
}
#endif
tm_enable();
/* This loads the checkpointed FP/VEC state, if used */
tm_recheckpoint(&current->thread, msr);
/* The task has moved into TM state S, so ensure MSR reflects this: */
regs->msr = (regs->msr & ~MSR_TS_MASK) | __MASK(33);
/* This loads the speculative FP/VEC state, if used */
if (msr & MSR_FP) {
do_load_up_transact_fpu(&current->thread);
regs->msr |= (MSR_FP | current->thread.fpexc_mode);
}
#ifdef CONFIG_ALTIVEC
if (msr & MSR_VEC) {
do_load_up_transact_altivec(&current->thread);
regs->msr |= MSR_VEC;
}
#endif
return err;
}
#endif
/*
* Setup the trampoline code on the stack
*/
static long setup_trampoline(unsigned int syscall, unsigned int __user *tramp)
{
int i;
long err = 0;
/* addi r1, r1, __SIGNAL_FRAMESIZE # Pop the dummy stackframe */
err |= __put_user(0x38210000UL | (__SIGNAL_FRAMESIZE & 0xffff), &tramp[0]);
/* li r0, __NR_[rt_]sigreturn| */
err |= __put_user(0x38000000UL | (syscall & 0xffff), &tramp[1]);
/* sc */
err |= __put_user(0x44000002UL, &tramp[2]);
/* Minimal traceback info */
for (i=TRAMP_TRACEBACK; i < TRAMP_SIZE ;i++)
err |= __put_user(0, &tramp[i]);
if (!err)
flush_icache_range((unsigned long) &tramp[0],
(unsigned long) &tramp[TRAMP_SIZE]);
return err;
}
/*
* Userspace code may pass a ucontext which doesn't include VSX added
* at the end. We need to check for this case.
*/
#define UCONTEXTSIZEWITHOUTVSX \
(sizeof(struct ucontext) - 32*sizeof(long))
/*
* Handle {get,set,swap}_context operations
*/
int sys_swapcontext(struct ucontext __user *old_ctx,
struct ucontext __user *new_ctx,
long ctx_size, long r6, long r7, long r8, struct pt_regs *regs)
{
unsigned char tmp;
sigset_t set;
unsigned long new_msr = 0;
int ctx_has_vsx_region = 0;
if (new_ctx &&
get_user(new_msr, &new_ctx->uc_mcontext.gp_regs[PT_MSR]))
return -EFAULT;
/*
* Check that the context is not smaller than the original
* size (with VMX but without VSX)
*/
if (ctx_size < UCONTEXTSIZEWITHOUTVSX)
return -EINVAL;
/*
* If the new context state sets the MSR VSX bits but
* it doesn't provide VSX state.
*/
if ((ctx_size < sizeof(struct ucontext)) &&
(new_msr & MSR_VSX))
return -EINVAL;
/* Does the context have enough room to store VSX data? */
if (ctx_size >= sizeof(struct ucontext))
ctx_has_vsx_region = 1;
if (old_ctx != NULL) {
if (!access_ok(VERIFY_WRITE, old_ctx, ctx_size)
|| setup_sigcontext(&old_ctx->uc_mcontext, regs, 0, NULL, 0,
ctx_has_vsx_region)
|| __copy_to_user(&old_ctx->uc_sigmask,
&current->blocked, sizeof(sigset_t)))
return -EFAULT;
}
if (new_ctx == NULL)
return 0;
if (!access_ok(VERIFY_READ, new_ctx, ctx_size)
|| __get_user(tmp, (u8 __user *) new_ctx)
|| __get_user(tmp, (u8 __user *) new_ctx + ctx_size - 1))
return -EFAULT;
/*
* If we get a fault copying the context into the kernel's
* image of the user's registers, we can't just return -EFAULT
* because the user's registers will be corrupted. For instance
* the NIP value may have been updated but not some of the
* other registers. Given that we have done the access_ok
* and successfully read the first and last bytes of the region
* above, this should only happen in an out-of-memory situation
* or if another thread unmaps the region containing the context.
* We kill the task with a SIGSEGV in this situation.
*/
if (__copy_from_user(&set, &new_ctx->uc_sigmask, sizeof(set)))
do_exit(SIGSEGV);
set_current_blocked(&set);
if (restore_sigcontext(regs, NULL, 0, &new_ctx->uc_mcontext))
do_exit(SIGSEGV);
/* This returns like rt_sigreturn */
set_thread_flag(TIF_RESTOREALL);
return 0;
}
/*
* Do a signal return; undo the signal stack.
*/
int sys_rt_sigreturn(unsigned long r3, unsigned long r4, unsigned long r5,
unsigned long r6, unsigned long r7, unsigned long r8,
struct pt_regs *regs)
{
struct ucontext __user *uc = (struct ucontext __user *)regs->gpr[1];
sigset_t set;
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
unsigned long msr;
#endif
/* Always make any pending restarted system calls return -EINTR */
current_thread_info()->restart_block.fn = do_no_restart_syscall;
if (!access_ok(VERIFY_READ, uc, sizeof(*uc)))
goto badframe;
if (__copy_from_user(&set, &uc->uc_sigmask, sizeof(set)))
goto badframe;
set_current_blocked(&set);
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
if (__get_user(msr, &uc->uc_mcontext.gp_regs[PT_MSR]))
goto badframe;
if (MSR_TM_SUSPENDED(msr)) {
/* We recheckpoint on return. */
struct ucontext __user *uc_transact;
if (__get_user(uc_transact, &uc->uc_link))
goto badframe;
if (restore_tm_sigcontexts(regs, &uc->uc_mcontext,
&uc_transact->uc_mcontext))
goto badframe;
}
else
/* Fall through, for non-TM restore */
#endif
if (restore_sigcontext(regs, NULL, 1, &uc->uc_mcontext))
goto badframe;
if (restore_altstack(&uc->uc_stack))
goto badframe;
set_thread_flag(TIF_RESTOREALL);
return 0;
badframe:
#if DEBUG_SIG
printk("badframe in sys_rt_sigreturn, regs=%p uc=%p &uc->uc_mcontext=%p\n",
regs, uc, &uc->uc_mcontext);
#endif
if (show_unhandled_signals)
printk_ratelimited(regs->msr & MSR_64BIT ? fmt64 : fmt32,
current->comm, current->pid, "rt_sigreturn",
(long)uc, regs->nip, regs->link);
force_sig(SIGSEGV, current);
return 0;
}
int handle_rt_signal64(int signr, struct k_sigaction *ka, siginfo_t *info,
sigset_t *set, struct pt_regs *regs)
{
/* Handler is *really* a pointer to the function descriptor for
* the signal routine. The first entry in the function
* descriptor is the entry address of signal and the second
* entry is the TOC value we need to use.
*/
func_descr_t __user *funct_desc_ptr;
struct rt_sigframe __user *frame;
unsigned long newsp = 0;
long err = 0;
frame = get_sigframe(ka, get_tm_stackpointer(regs), sizeof(*frame), 0);
if (unlikely(frame == NULL))
goto badframe;
err |= __put_user(&frame->info, &frame->pinfo);
err |= __put_user(&frame->uc, &frame->puc);
err |= copy_siginfo_to_user(&frame->info, info);
if (err)
goto badframe;
/* Create the ucontext. */
err |= __put_user(0, &frame->uc.uc_flags);
err |= __save_altstack(&frame->uc.uc_stack, regs->gpr[1]);
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
if (MSR_TM_ACTIVE(regs->msr)) {
/* The ucontext_t passed to userland points to the second
* ucontext_t (for transactional state) with its uc_link ptr.
*/
err |= __put_user(&frame->uc_transact, &frame->uc.uc_link);
err |= setup_tm_sigcontexts(&frame->uc.uc_mcontext,
&frame->uc_transact.uc_mcontext,
regs, signr,
NULL,
(unsigned long)ka->sa.sa_handler);
} else
#endif
{
err |= __put_user(0, &frame->uc.uc_link);
err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, signr,
NULL, (unsigned long)ka->sa.sa_handler,
1);
}
err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
if (err)
goto badframe;
/* Make sure signal handler doesn't get spurious FP exceptions */
current->thread.fpscr.val = 0;
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
/* Remove TM bits from thread's MSR. The MSR in the sigcontext
* just indicates to userland that we were doing a transaction, but we
* don't want to return in transactional state:
*/
regs->msr &= ~MSR_TS_MASK;
#endif
/* Set up to return from userspace. */
if (vdso64_rt_sigtramp && current->mm->context.vdso_base) {
regs->link = current->mm->context.vdso_base + vdso64_rt_sigtramp;
} else {
err |= setup_trampoline(__NR_rt_sigreturn, &frame->tramp[0]);
if (err)
goto badframe;
regs->link = (unsigned long) &frame->tramp[0];
}
funct_desc_ptr = (func_descr_t __user *) ka->sa.sa_handler;
/* Allocate a dummy caller frame for the signal handler. */
newsp = ((unsigned long)frame) - __SIGNAL_FRAMESIZE;
err |= put_user(regs->gpr[1], (unsigned long __user *)newsp);
/* Set up "regs" so we "return" to the signal handler. */
err |= get_user(regs->nip, &funct_desc_ptr->entry);
/* enter the signal handler in big-endian mode */
regs->msr &= ~MSR_LE;
regs->gpr[1] = newsp;
err |= get_user(regs->gpr[2], &funct_desc_ptr->toc);
regs->gpr[3] = signr;
regs->result = 0;
if (ka->sa.sa_flags & SA_SIGINFO) {
err |= get_user(regs->gpr[4], (unsigned long __user *)&frame->pinfo);
err |= get_user(regs->gpr[5], (unsigned long __user *)&frame->puc);
regs->gpr[6] = (unsigned long) frame;
} else {
regs->gpr[4] = (unsigned long)&frame->uc.uc_mcontext;
}
if (err)
goto badframe;
return 1;
badframe:
#if DEBUG_SIG
printk("badframe in setup_rt_frame, regs=%p frame=%p newsp=%lx\n",
regs, frame, newsp);
#endif
if (show_unhandled_signals)
printk_ratelimited(regs->msr & MSR_64BIT ? fmt64 : fmt32,
current->comm, current->pid, "setup_rt_frame",
(long)frame, regs->nip, regs->link);
force_sigsegv(signr, current);
return 0;
}
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