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alistair23-linux/arch/powerpc/kernel/signal_64.c
Linus Torvalds 5ad18b2e60 Merge branch 'siginfo-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 
Pull force_sig() argument change from Eric Biederman:
 "A source of error over the years has been that force_sig has taken a
  task parameter when it is only safe to use force_sig with the current
  task.

  The force_sig function is built for delivering synchronous signals
  such as SIGSEGV where the userspace application caused a synchronous
  fault (such as a page fault) and the kernel responded with a signal.

  Because the name force_sig does not make this clear, and because the
  force_sig takes a task parameter the function force_sig has been
  abused for sending other kinds of signals over the years. Slowly those
  have been fixed when the oopses have been tracked down.

  This set of changes fixes the remaining abusers of force_sig and
  carefully rips out the task parameter from force_sig and friends
  making this kind of error almost impossible in the future"

* 'siginfo-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (27 commits)
  signal/x86: Move tsk inside of CONFIG_MEMORY_FAILURE in do_sigbus
  signal: Remove the signal number and task parameters from force_sig_info
  signal: Factor force_sig_info_to_task out of force_sig_info
  signal: Generate the siginfo in force_sig
  signal: Move the computation of force into send_signal and correct it.
  signal: Properly set TRACE_SIGNAL_LOSE_INFO in __send_signal
  signal: Remove the task parameter from force_sig_fault
  signal: Use force_sig_fault_to_task for the two calls that don't deliver to current
  signal: Explicitly call force_sig_fault on current
  signal/unicore32: Remove tsk parameter from __do_user_fault
  signal/arm: Remove tsk parameter from __do_user_fault
  signal/arm: Remove tsk parameter from ptrace_break
  signal/nds32: Remove tsk parameter from send_sigtrap
  signal/riscv: Remove tsk parameter from do_trap
  signal/sh: Remove tsk parameter from force_sig_info_fault
  signal/um: Remove task parameter from send_sigtrap
  signal/x86: Remove task parameter from send_sigtrap
  signal: Remove task parameter from force_sig_mceerr
  signal: Remove task parameter from force_sig
  signal: Remove task parameter from force_sigsegv
  ...
2019-07-08 21:48:15 -07:00

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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* 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
*/
#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 <linux/syscalls.h>
#include <asm/sigcontext.h>
#include <asm/ucontext.h>
#include <linux/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 <asm/asm-prototypes.h>
#include "signal.h"
#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;
/* New 64 bit little-endian ABI allows redzone of 512 bytes below sp */
char abigap[USER_REDZONE_SIZE];
} __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";
/*
* This computes a quad word aligned pointer inside the vmx_reserve array
* element. For historical reasons sigcontext might not be quad word aligned,
* but the location we write the VMX regs to must be. See the comment in
* sigcontext for more detail.
*/
#ifdef CONFIG_ALTIVEC
static elf_vrreg_t __user *sigcontext_vmx_regs(struct sigcontext __user *sc)
{
return (elf_vrreg_t __user *) (((unsigned long)sc->vmx_reserve + 15) & ~0xful);
}
#endif
/*
* Set up the sigcontext for the signal frame.
*/
static long setup_sigcontext(struct sigcontext __user *sc,
struct task_struct *tsk, 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 = sigcontext_vmx_regs(sc);
unsigned long vrsave;
#endif
struct pt_regs *regs = tsk->thread.regs;
unsigned long msr = regs->msr;
long err = 0;
/* Force usr to alway see softe as 1 (interrupts enabled) */
unsigned long softe = 0x1;
BUG_ON(tsk != current);
#ifdef CONFIG_ALTIVEC
err |= __put_user(v_regs, &sc->v_regs);
/* save altivec registers */
if (tsk->thread.used_vr) {
flush_altivec_to_thread(tsk);
/* Copy 33 vec registers (vr0..31 and vscr) to the stack */
err |= __copy_to_user(v_regs, &tsk->thread.vr_state,
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.
*/
vrsave = 0;
if (cpu_has_feature(CPU_FTR_ALTIVEC)) {
vrsave = mfspr(SPRN_VRSAVE);
tsk->thread.vrsave = vrsave;
}
err |= __put_user(vrsave, (u32 __user *)&v_regs[33]);
#else /* CONFIG_ALTIVEC */
err |= __put_user(0, &sc->v_regs);
#endif /* CONFIG_ALTIVEC */
flush_fp_to_thread(tsk);
/* copy fpr regs and fpscr */
err |= copy_fpr_to_user(&sc->fp_regs, tsk);
/*
* Clear the MSR VSX bit to indicate there is no valid state attached
* to this context, except in the specific case below where we set it.
*/
msr &= ~MSR_VSX;
#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 (tsk->thread.used_vsr && ctx_has_vsx_region) {
flush_vsx_to_thread(tsk);
v_regs += ELF_NVRREG;
err |= copy_vsx_to_user(v_regs, tsk);
/* 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(softe, &sc->gp_regs[PT_SOFTE]);
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 task_struct *tsk,
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 = sigcontext_vmx_regs(sc);
elf_vrreg_t __user *tm_v_regs = sigcontext_vmx_regs(tm_sc);
#endif
struct pt_regs *regs = tsk->thread.regs;
unsigned long msr = tsk->thread.regs->msr;
long err = 0;
BUG_ON(tsk != current);
BUG_ON(!MSR_TM_ACTIVE(regs->msr));
WARN_ON(tm_suspend_disabled);
/* Restore checkpointed FP, VEC, and VSX bits from ckpt_regs as
* it contains the correct FP, VEC, VSX state after we treclaimed
* the transaction and giveup_all() was called on reclaiming.
*/
msr |= tsk->thread.ckpt_regs.msr & (MSR_FP | MSR_VEC | MSR_VSX);
/* 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. This also ensures
* that flush_fp_to_thread won't set TIF_RESTORE_TM again.
*/
regs->msr &= ~MSR_TS_MASK;
#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 (tsk->thread.used_vr) {
/* Copy 33 vec registers (vr0..31 and vscr) to the stack */
err |= __copy_to_user(v_regs, &tsk->thread.ckvr_state,
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,
&tsk->thread.vr_state,
33 * sizeof(vector128));
else
err |= __copy_to_user(tm_v_regs,
&tsk->thread.ckvr_state,
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.
*/
if (cpu_has_feature(CPU_FTR_ALTIVEC))
tsk->thread.ckvrsave = mfspr(SPRN_VRSAVE);
err |= __put_user(tsk->thread.ckvrsave, (u32 __user *)&v_regs[33]);
if (msr & MSR_VEC)
err |= __put_user(tsk->thread.vrsave,
(u32 __user *)&tm_v_regs[33]);
else
err |= __put_user(tsk->thread.ckvrsave,
(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_ckfpr_to_user(&sc->fp_regs, tsk);
if (msr & MSR_FP)
err |= copy_fpr_to_user(&tm_sc->fp_regs, tsk);
else
err |= copy_ckfpr_to_user(&tm_sc->fp_regs, tsk);
#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 (tsk->thread.used_vsr) {
v_regs += ELF_NVRREG;
tm_v_regs += ELF_NVRREG;
err |= copy_ckvsx_to_user(v_regs, tsk);
if (msr & MSR_VSX)
err |= copy_vsx_to_user(tm_v_regs, tsk);
else
err |= copy_ckvsx_to_user(tm_v_regs, tsk);
/* 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,
&tsk->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 task_struct *tsk, 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;
struct pt_regs *regs = tsk->thread.regs;
#ifdef CONFIG_VSX
int i;
#endif
BUG_ON(tsk != current);
/* 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);
/*
* Force reload of FP/VEC.
* This has to be done before copying stuff into tsk->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(v_regs, 34 * sizeof(vector128)))
return -EFAULT;
/* Copy 33 vec registers (vr0..31 and vscr) from the stack */
if (v_regs != NULL && (msr & MSR_VEC) != 0) {
err |= __copy_from_user(&tsk->thread.vr_state, v_regs,
33 * sizeof(vector128));
tsk->thread.used_vr = true;
} else if (tsk->thread.used_vr) {
memset(&tsk->thread.vr_state, 0, 33 * sizeof(vector128));
}
/* Always get VRSAVE back */
if (v_regs != NULL)
err |= __get_user(tsk->thread.vrsave, (u32 __user *)&v_regs[33]);
else
tsk->thread.vrsave = 0;
if (cpu_has_feature(CPU_FTR_ALTIVEC))
mtspr(SPRN_VRSAVE, tsk->thread.vrsave);
#endif /* CONFIG_ALTIVEC */
/* restore floating point */
err |= copy_fpr_from_user(tsk, &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(tsk, v_regs);
tsk->thread.used_vsr = true;
} else {
for (i = 0; i < 32 ; i++)
tsk->thread.fp_state.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 task_struct *tsk,
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;
struct pt_regs *regs = tsk->thread.regs;
#ifdef CONFIG_VSX
int i;
#endif
BUG_ON(tsk != current);
if (tm_suspend_disabled)
return -EINVAL;
/* copy the GPRs */
err |= __copy_from_user(regs->gpr, tm_sc->gp_regs, sizeof(regs->gpr));
err |= __copy_from_user(&tsk->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(tsk->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]);
/* Don't allow reserved mode. */
if (MSR_TM_RESV(msr))
return -EINVAL;
/* pull in MSR LE from user context */
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(tsk->thread.ckpt_regs.ctr,
&sc->gp_regs[PT_CTR]);
err |= __get_user(tsk->thread.ckpt_regs.link,
&sc->gp_regs[PT_LNK]);
err |= __get_user(tsk->thread.ckpt_regs.xer,
&sc->gp_regs[PT_XER]);
err |= __get_user(tsk->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]);
/*
* Force reload of FP/VEC.
* This has to be done before copying stuff into tsk->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(v_regs, 34 * sizeof(vector128)))
return -EFAULT;
if (tm_v_regs && !access_ok(tm_v_regs, 34 * sizeof(vector128)))
return -EFAULT;
/* Copy 33 vec registers (vr0..31 and vscr) from the stack */
if (v_regs != NULL && tm_v_regs != NULL && (msr & MSR_VEC) != 0) {
err |= __copy_from_user(&tsk->thread.ckvr_state, v_regs,
33 * sizeof(vector128));
err |= __copy_from_user(&tsk->thread.vr_state, tm_v_regs,
33 * sizeof(vector128));
current->thread.used_vr = true;
}
else if (tsk->thread.used_vr) {
memset(&tsk->thread.vr_state, 0, 33 * sizeof(vector128));
memset(&tsk->thread.ckvr_state, 0, 33 * sizeof(vector128));
}
/* Always get VRSAVE back */
if (v_regs != NULL && tm_v_regs != NULL) {
err |= __get_user(tsk->thread.ckvrsave,
(u32 __user *)&v_regs[33]);
err |= __get_user(tsk->thread.vrsave,
(u32 __user *)&tm_v_regs[33]);
}
else {
tsk->thread.vrsave = 0;
tsk->thread.ckvrsave = 0;
}
if (cpu_has_feature(CPU_FTR_ALTIVEC))
mtspr(SPRN_VRSAVE, tsk->thread.vrsave);
#endif /* CONFIG_ALTIVEC */
/* restore floating point */
err |= copy_fpr_from_user(tsk, &tm_sc->fp_regs);
err |= copy_ckfpr_from_user(tsk, &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(tsk, tm_v_regs);
err |= copy_ckvsx_from_user(tsk, v_regs);
tsk->thread.used_vsr = true;
} else {
for (i = 0; i < 32 ; i++) {
tsk->thread.fp_state.fpr[i][TS_VSRLOWOFFSET] = 0;
tsk->thread.ckfp_state.fpr[i][TS_VSRLOWOFFSET] = 0;
}
}
#endif
tm_enable();
/* Make sure the transaction is marked as failed */
tsk->thread.tm_texasr |= TEXASR_FS;
/*
* Disabling preemption, since it is unsafe to be preempted
* with MSR[TS] set without recheckpointing.
*/
preempt_disable();
/* pull in MSR TS bits from user context */
regs->msr |= msr & MSR_TS_MASK;
/*
* Ensure that TM is enabled in regs->msr before we leave the signal
* handler. It could be the case that (a) user disabled the TM bit
* through the manipulation of the MSR bits in uc_mcontext or (b) the
* TM bit was disabled because a sufficient number of context switches
* happened whilst in the signal handler and load_tm overflowed,
* disabling the TM bit. In either case we can end up with an illegal
* TM state leading to a TM Bad Thing when we return to userspace.
*
* CAUTION:
* After regs->MSR[TS] being updated, make sure that get_user(),
* put_user() or similar functions are *not* called. These
* functions can generate page faults which will cause the process
* to be de-scheduled with MSR[TS] set but without calling
* tm_recheckpoint(). This can cause a bug.
*/
regs->msr |= MSR_TM;
/* This loads the checkpointed FP/VEC state, if used */
tm_recheckpoint(&tsk->thread);
msr_check_and_set(msr & (MSR_FP | MSR_VEC));
if (msr & MSR_FP) {
load_fp_state(&tsk->thread.fp_state);
regs->msr |= (MSR_FP | tsk->thread.fpexc_mode);
}
if (msr & MSR_VEC) {
load_vr_state(&tsk->thread.vr_state);
regs->msr |= MSR_VEC;
}
preempt_enable();
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(PPC_INST_ADDI | __PPC_RT(R1) | __PPC_RA(R1) |
(__SIGNAL_FRAMESIZE & 0xffff), &tramp[0]);
/* li r0, __NR_[rt_]sigreturn| */
err |= __put_user(PPC_INST_ADDI | (syscall & 0xffff), &tramp[1]);
/* sc */
err |= __put_user(PPC_INST_SC, &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
*/
SYSCALL_DEFINE3(swapcontext, struct ucontext __user *, old_ctx,
struct ucontext __user *, new_ctx, long, ctx_size)
{
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(old_ctx, ctx_size)
|| setup_sigcontext(&old_ctx->uc_mcontext, current, 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(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(current, 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.
*/
SYSCALL_DEFINE0(rt_sigreturn)
{
struct pt_regs *regs = current_pt_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->restart_block.fn = do_no_restart_syscall;
if (!access_ok(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 there is a transactional state then throw it away.
* The purpose of a sigreturn is to destroy all traces of the
* signal frame, this includes any transactional state created
* within in. We only check for suspended as we can never be
* active in the kernel, we are active, there is nothing better to
* do than go ahead and Bad Thing later.
* The cause is not important as there will never be a
* recheckpoint so it's not user visible.
*/
if (MSR_TM_SUSPENDED(mfmsr()))
tm_reclaim_current(0);
/*
* Disable MSR[TS] bit also, so, if there is an exception in the
* code below (as a page fault in copy_ckvsx_to_user()), it does
* not recheckpoint this task if there was a context switch inside
* the exception.
*
* A major page fault can indirectly call schedule(). A reschedule
* process in the middle of an exception can have a side effect
* (Changing the CPU MSR[TS] state), since schedule() is called
* with the CPU MSR[TS] disable and returns with MSR[TS]=Suspended
* (switch_to() calls tm_recheckpoint() for the 'new' process). In
* this case, the process continues to be the same in the CPU, but
* the CPU state just changed.
*
* This can cause a TM Bad Thing, since the MSR in the stack will
* have the MSR[TS]=0, and this is what will be used to RFID.
*
* Clearing MSR[TS] state here will avoid a recheckpoint if there
* is any process reschedule in kernel space. The MSR[TS] state
* does not need to be saved also, since it will be replaced with
* the MSR[TS] that came from user context later, at
* restore_tm_sigcontexts.
*/
regs->msr &= ~MSR_TS_MASK;
if (__get_user(msr, &uc->uc_mcontext.gp_regs[PT_MSR]))
goto badframe;
if (MSR_TM_ACTIVE(msr)) {
/* We recheckpoint on return. */
struct ucontext __user *uc_transact;
if (__get_user(uc_transact, &uc->uc_link))
goto badframe;
if (restore_tm_sigcontexts(current, &uc->uc_mcontext,
&uc_transact->uc_mcontext))
goto badframe;
} else
#endif
{
/*
* Fall through, for non-TM restore
*
* Unset MSR[TS] on the thread regs since MSR from user
* context does not have MSR active, and recheckpoint was
* not called since restore_tm_sigcontexts() was not called
* also.
*
* If not unsetting it, the code can RFID to userspace with
* MSR[TS] set, but without CPU in the proper state,
* causing a TM bad thing.
*/
current->thread.regs->msr &= ~MSR_TS_MASK;
if (restore_sigcontext(current, NULL, 1, &uc->uc_mcontext))
goto badframe;
}
if (restore_altstack(&uc->uc_stack))
goto badframe;
set_thread_flag(TIF_RESTOREALL);
return 0;
badframe:
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);
return 0;
}
int handle_rt_signal64(struct ksignal *ksig, sigset_t *set,
struct task_struct *tsk)
{
struct rt_sigframe __user *frame;
unsigned long newsp = 0;
long err = 0;
struct pt_regs *regs = tsk->thread.regs;
BUG_ON(tsk != current);
frame = get_sigframe(ksig, get_tm_stackpointer(tsk), 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, &ksig->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,
tsk, ksig->sig, NULL,
(unsigned long)ksig->ka.sa.sa_handler);
} else
#endif
{
err |= __put_user(0, &frame->uc.uc_link);
err |= setup_sigcontext(&frame->uc.uc_mcontext, tsk, ksig->sig,
NULL, (unsigned long)ksig->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 */
tsk->thread.fp_state.fpscr = 0;
/* Set up to return from userspace. */
if (vdso64_rt_sigtramp && tsk->mm->context.vdso_base) {
regs->link = tsk->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];
}
/* 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. */
if (is_elf2_task()) {
regs->nip = (unsigned long) ksig->ka.sa.sa_handler;
regs->gpr[12] = regs->nip;
} else {
/* 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 =
(func_descr_t __user *) ksig->ka.sa.sa_handler;
err |= get_user(regs->nip, &funct_desc_ptr->entry);
err |= get_user(regs->gpr[2], &funct_desc_ptr->toc);
}
/* enter the signal handler in native-endian mode */
regs->msr &= ~MSR_LE;
regs->msr |= (MSR_KERNEL & MSR_LE);
regs->gpr[1] = newsp;
regs->gpr[3] = ksig->sig;
regs->result = 0;
if (ksig->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 0;
badframe:
if (show_unhandled_signals)
printk_ratelimited(regs->msr & MSR_64BIT ? fmt64 : fmt32,
tsk->comm, tsk->pid, "setup_rt_frame",
(long)frame, regs->nip, regs->link);
return 1;
}
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