diff options
Diffstat (limited to 'arch/powerpc/kernel/signal_64.c')
| -rw-r--r-- | arch/powerpc/kernel/signal_64.c | 977 |
1 files changed, 977 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c new file mode 100644 index 000000000..86bb5bb4c --- /dev/null +++ b/arch/powerpc/kernel/signal_64.c @@ -0,0 +1,977 @@ +// 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 <linux/pagemap.h> + +#include <asm/sigcontext.h> +#include <asm/ucontext.h> +#include <linux/uaccess.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 4 +#define TRAMP_SIZE 7 + +/* + * 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))); + +unsigned long get_min_sigframe_size_64(void) +{ + return sizeof(struct rt_sigframe) + __SIGNAL_FRAMESIZE; +} + +/* + * 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 + +static void prepare_setup_sigcontext(struct task_struct *tsk) +{ +#ifdef CONFIG_ALTIVEC + /* save altivec registers */ + if (tsk->thread.used_vr) + flush_altivec_to_thread(tsk); + if (cpu_has_feature(CPU_FTR_ALTIVEC)) + tsk->thread.vrsave = mfspr(SPRN_VRSAVE); +#endif /* CONFIG_ALTIVEC */ + + flush_fp_to_thread(tsk); + +#ifdef CONFIG_VSX + if (tsk->thread.used_vsr) + flush_vsx_to_thread(tsk); +#endif /* CONFIG_VSX */ +} + +/* + * Set up the sigcontext for the signal frame. + */ + +#define unsafe_setup_sigcontext(sc, tsk, signr, set, handler, ctx_has_vsx_region, label)\ +do { \ + if (__unsafe_setup_sigcontext(sc, tsk, signr, set, handler, ctx_has_vsx_region))\ + goto label; \ +} while (0) +static long notrace __unsafe_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); +#endif + struct pt_regs *regs = tsk->thread.regs; + unsigned long msr = regs->msr; + /* Force usr to always see softe as 1 (interrupts enabled) */ + unsigned long softe = 0x1; + + BUG_ON(tsk != current); + +#ifdef CONFIG_ALTIVEC + unsafe_put_user(v_regs, &sc->v_regs, efault_out); + + /* save altivec registers */ + if (tsk->thread.used_vr) { + /* Copy 33 vec registers (vr0..31 and vscr) to the stack */ + unsafe_copy_to_user(v_regs, &tsk->thread.vr_state, + 33 * sizeof(vector128), efault_out); + /* 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. + */ + unsafe_put_user(tsk->thread.vrsave, (u32 __user *)&v_regs[33], efault_out); +#else /* CONFIG_ALTIVEC */ + unsafe_put_user(0, &sc->v_regs, efault_out); +#endif /* CONFIG_ALTIVEC */ + /* copy fpr regs and fpscr */ + unsafe_copy_fpr_to_user(&sc->fp_regs, tsk, efault_out); + + /* + * 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) { + v_regs += ELF_NVRREG; + unsafe_copy_vsx_to_user(v_regs, tsk, efault_out); + /* 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 */ + unsafe_put_user(&sc->gp_regs, &sc->regs, efault_out); + unsafe_copy_to_user(&sc->gp_regs, regs, GP_REGS_SIZE, efault_out); + unsafe_put_user(msr, &sc->gp_regs[PT_MSR], efault_out); + unsafe_put_user(softe, &sc->gp_regs[PT_SOFTE], efault_out); + unsafe_put_user(signr, &sc->signal, efault_out); + unsafe_put_user(handler, &sc->handler, efault_out); + if (set != NULL) + unsafe_put_user(set->sig[0], &sc->oldmask, efault_out); + + return 0; + +efault_out: + return -EFAULT; +} + +#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, + unsigned long msr) +{ + /* 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; + long err = 0; + + BUG_ON(tsk != current); + + BUG_ON(!MSR_TM_ACTIVE(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); + +#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); + 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. + */ +#define unsafe_restore_sigcontext(tsk, set, sig, sc, label) do { \ + if (__unsafe_restore_sigcontext(tsk, set, sig, sc)) \ + goto label; \ +} while (0) +static long notrace __unsafe_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 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 */ + unsafe_copy_from_user(regs->gpr, sc->gp_regs, sizeof(regs->gpr), efault_out); + unsafe_get_user(regs->nip, &sc->gp_regs[PT_NIP], efault_out); + /* get MSR separately, transfer the LE bit if doing signal return */ + unsafe_get_user(msr, &sc->gp_regs[PT_MSR], efault_out); + if (sig) + regs_set_return_msr(regs, (regs->msr & ~MSR_LE) | (msr & MSR_LE)); + unsafe_get_user(regs->orig_gpr3, &sc->gp_regs[PT_ORIG_R3], efault_out); + unsafe_get_user(regs->ctr, &sc->gp_regs[PT_CTR], efault_out); + unsafe_get_user(regs->link, &sc->gp_regs[PT_LNK], efault_out); + unsafe_get_user(regs->xer, &sc->gp_regs[PT_XER], efault_out); + unsafe_get_user(regs->ccr, &sc->gp_regs[PT_CCR], efault_out); + /* Don't allow userspace to set SOFTE */ + set_trap_norestart(regs); + unsafe_get_user(regs->dar, &sc->gp_regs[PT_DAR], efault_out); + unsafe_get_user(regs->dsisr, &sc->gp_regs[PT_DSISR], efault_out); + unsafe_get_user(regs->result, &sc->gp_regs[PT_RESULT], efault_out); + + if (!sig) + regs->gpr[13] = save_r13; + if (set != NULL) + unsafe_get_user(set->sig[0], &sc->oldmask, efault_out); + + /* + * Force reload of FP/VEC/VSX so userspace sees any changes. + * Clear these bits from the user process' MSR before copying into the + * thread struct. If we are rescheduled or preempted and another task + * uses FP/VEC/VSX, and this process has the MSR bits set, then the + * context switch code will save the current CPU state into the + * thread_struct - possibly overwriting the data we are updating here. + */ + regs_set_return_msr(regs, regs->msr & ~(MSR_FP | MSR_FE0 | MSR_FE1 | MSR_VEC | MSR_VSX)); + +#ifdef CONFIG_ALTIVEC + unsafe_get_user(v_regs, &sc->v_regs, efault_out); + 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) { + unsafe_copy_from_user(&tsk->thread.vr_state, v_regs, + 33 * sizeof(vector128), efault_out); + 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) + unsafe_get_user(tsk->thread.vrsave, (u32 __user *)&v_regs[33], efault_out); + else + tsk->thread.vrsave = 0; + if (cpu_has_feature(CPU_FTR_ALTIVEC)) + mtspr(SPRN_VRSAVE, tsk->thread.vrsave); +#endif /* CONFIG_ALTIVEC */ + /* restore floating point */ + unsafe_copy_fpr_from_user(tsk, &sc->fp_regs, efault_out); +#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) { + unsafe_copy_vsx_from_user(tsk, v_regs, efault_out); + tsk->thread.used_vsr = true; + } else { + for (i = 0; i < 32 ; i++) + tsk->thread.fp_state.fpr[i][TS_VSRLOWOFFSET] = 0; + } +#endif + return 0; + +efault_out: + return -EFAULT; +} + +#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_set_return_msr(regs, (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]); + /* Don't allow userspace to set SOFTE */ + set_trap_norestart(regs); + /* These regs are not checkpointed; they can go in 'regs'. */ + 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_set_return_msr(regs, 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_set_return_msr(regs, 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_set_return_msr(regs, 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_set_return_msr(regs, regs->msr | (MSR_FP | tsk->thread.fpexc_mode)); + } + if (msr & MSR_VEC) { + load_vr_state(&tsk->thread.vr_state); + regs_set_return_msr(regs, regs->msr | MSR_VEC); + } + + preempt_enable(); + + return err; +} +#else /* !CONFIG_PPC_TRANSACTIONAL_MEM */ +static long restore_tm_sigcontexts(struct task_struct *tsk, struct sigcontext __user *sc, + struct sigcontext __user *tm_sc) +{ + return -EINVAL; +} +#endif + +/* + * Setup the trampoline code on the stack + */ +static long setup_trampoline(unsigned int syscall, unsigned int __user *tramp) +{ + int i; + long err = 0; + + /* Call the handler and pop the dummy stackframe*/ + err |= __put_user(PPC_RAW_BCTRL(), &tramp[0]); + err |= __put_user(PPC_RAW_ADDI(_R1, _R1, __SIGNAL_FRAMESIZE), &tramp[1]); + + err |= __put_user(PPC_RAW_LI(_R0, syscall), &tramp[2]); + err |= __put_user(PPC_RAW_SC(), &tramp[3]); + + /* 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) +{ + 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) { + prepare_setup_sigcontext(current); + if (!user_write_access_begin(old_ctx, ctx_size)) + return -EFAULT; + + unsafe_setup_sigcontext(&old_ctx->uc_mcontext, current, 0, NULL, + 0, ctx_has_vsx_region, efault_out); + unsafe_copy_to_user(&old_ctx->uc_sigmask, ¤t->blocked, + sizeof(sigset_t), efault_out); + + user_write_access_end(); + } + if (new_ctx == NULL) + return 0; + if (!access_ok(new_ctx, ctx_size) || + fault_in_readable((char __user *)new_ctx, ctx_size)) + 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 (__get_user_sigset(&set, &new_ctx->uc_sigmask)) { + force_exit_sig(SIGSEGV); + return -EFAULT; + } + set_current_blocked(&set); + + if (!user_read_access_begin(new_ctx, ctx_size)) + return -EFAULT; + if (__unsafe_restore_sigcontext(current, NULL, 0, &new_ctx->uc_mcontext)) { + user_read_access_end(); + force_exit_sig(SIGSEGV); + return -EFAULT; + } + user_read_access_end(); + + /* This returns like rt_sigreturn */ + set_thread_flag(TIF_RESTOREALL); + + return 0; + +efault_out: + user_write_access_end(); + return -EFAULT; +} + + +/* + * 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; + unsigned long msr; + + /* 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 (__get_user_sigset(&set, &uc->uc_sigmask)) + goto badframe; + set_current_blocked(&set); + + if (IS_ENABLED(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_set_return_msr(regs, regs->msr & ~MSR_TS_MASK); + + if (__get_user(msr, &uc->uc_mcontext.gp_regs[PT_MSR])) + goto badframe; + } + + if (IS_ENABLED(CONFIG_PPC_TRANSACTIONAL_MEM) && MSR_TM_ACTIVE(msr)) { + /* We recheckpoint on return. */ + struct ucontext __user *uc_transact; + + /* Trying to start TM on non TM system */ + if (!cpu_has_feature(CPU_FTR_TM)) + goto badframe; + + 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 { + /* + * 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. + */ + regs_set_return_msr(current->thread.regs, + current->thread.regs->msr & ~MSR_TS_MASK); + if (!user_read_access_begin(&uc->uc_mcontext, sizeof(uc->uc_mcontext))) + goto badframe; + + unsafe_restore_sigcontext(current, NULL, 1, &uc->uc_mcontext, + badframe_block); + + user_read_access_end(); + } + + if (restore_altstack(&uc->uc_stack)) + goto badframe; + + set_thread_flag(TIF_RESTOREALL); + + return 0; + +badframe_block: + user_read_access_end(); +badframe: + signal_fault(current, regs, "rt_sigreturn", uc); + + 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; + /* Save the thread's msr before get_tm_stackpointer() changes it */ + unsigned long msr = regs->msr; + + frame = get_sigframe(ksig, tsk, sizeof(*frame), 0); + + /* + * This only applies when calling unsafe_setup_sigcontext() and must be + * called before opening the uaccess window. + */ + if (!MSR_TM_ACTIVE(msr)) + prepare_setup_sigcontext(tsk); + + if (!user_write_access_begin(frame, sizeof(*frame))) + goto badframe; + + unsafe_put_user(&frame->info, &frame->pinfo, badframe_block); + unsafe_put_user(&frame->uc, &frame->puc, badframe_block); + + /* Create the ucontext. */ + unsafe_put_user(0, &frame->uc.uc_flags, badframe_block); + unsafe_save_altstack(&frame->uc.uc_stack, regs->gpr[1], badframe_block); + + if (MSR_TM_ACTIVE(msr)) { +#ifdef CONFIG_PPC_TRANSACTIONAL_MEM + /* The ucontext_t passed to userland points to the second + * ucontext_t (for transactional state) with its uc_link ptr. + */ + unsafe_put_user(&frame->uc_transact, &frame->uc.uc_link, badframe_block); + + user_write_access_end(); + + err |= setup_tm_sigcontexts(&frame->uc.uc_mcontext, + &frame->uc_transact.uc_mcontext, + tsk, ksig->sig, NULL, + (unsigned long)ksig->ka.sa.sa_handler, + msr); + + if (!user_write_access_begin(&frame->uc.uc_sigmask, + sizeof(frame->uc.uc_sigmask))) + goto badframe; + +#endif + } else { + unsafe_put_user(0, &frame->uc.uc_link, badframe_block); + unsafe_setup_sigcontext(&frame->uc.uc_mcontext, tsk, ksig->sig, + NULL, (unsigned long)ksig->ka.sa.sa_handler, + 1, badframe_block); + } + + unsafe_copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set), badframe_block); + user_write_access_end(); + + /* Save the siginfo outside of the unsafe block. */ + if (copy_siginfo_to_user(&frame->info, &ksig->info)) + 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 (tsk->mm->context.vdso) { + regs_set_return_ip(regs, VDSO64_SYMBOL(tsk->mm->context.vdso, sigtramp_rt64)); + } else { + err |= setup_trampoline(__NR_rt_sigreturn, &frame->tramp[0]); + if (err) + goto badframe; + regs_set_return_ip(regs, (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->ctr = (unsigned long) ksig->ka.sa.sa_handler; + regs->gpr[12] = regs->ctr; + } 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. + */ + struct func_desc __user *ptr = + (struct func_desc __user *)ksig->ka.sa.sa_handler; + + err |= get_user(regs->ctr, &ptr->addr); + err |= get_user(regs->gpr[2], &ptr->toc); + } + + /* enter the signal handler in native-endian mode */ + regs_set_return_msr(regs, (regs->msr & ~MSR_LE) | (MSR_KERNEL & MSR_LE)); + regs->gpr[1] = newsp; + regs->gpr[3] = ksig->sig; + regs->result = 0; + if (ksig->ka.sa.sa_flags & SA_SIGINFO) { + regs->gpr[4] = (unsigned long)&frame->info; + regs->gpr[5] = (unsigned long)&frame->uc; + regs->gpr[6] = (unsigned long) frame; + } else { + regs->gpr[4] = (unsigned long)&frame->uc.uc_mcontext; + } + if (err) + goto badframe; + + return 0; + +badframe_block: + user_write_access_end(); +badframe: + signal_fault(current, regs, "handle_rt_signal64", frame); + + return 1; +} |