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OpenCloudOS-Kernel/arch/loongarch/kernel/signal.c

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// SPDX-License-Identifier: GPL-2.0+
/*
* Author: Hanlu Li <lihanlu@loongson.cn>
* Huacai Chen <chenhuacai@loongson.cn>
* Copyright (C) 2020-2022 Loongson Technology Corporation Limited
*
* Derived from MIPS:
* Copyright (C) 1991, 1992 Linus Torvalds
* Copyright (C) 1994 - 2000 Ralf Baechle
* Copyright (C) 1999, 2000 Silicon Graphics, Inc.
* Copyright (C) 2014, Imagination Technologies Ltd.
*/
#include <linux/audit.h>
#include <linux/cache.h>
#include <linux/context_tracking.h>
#include <linux/irqflags.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/personality.h>
#include <linux/smp.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/errno.h>
#include <linux/wait.h>
#include <linux/ptrace.h>
#include <linux/unistd.h>
#include <linux/compiler.h>
#include <linux/syscalls.h>
#include <linux/uaccess.h>
#include <asm/asm.h>
#include <asm/cacheflush.h>
#include <asm/cpu-features.h>
#include <asm/fpu.h>
#include <asm/ucontext.h>
#include <asm/vdso.h>
#ifdef DEBUG_SIG
# define DEBUGP(fmt, args...) printk("%s: " fmt, __func__, ##args)
#else
# define DEBUGP(fmt, args...)
#endif
/* Make sure we will not lose FPU ownership */
#define lock_fpu_owner() ({ preempt_disable(); pagefault_disable(); })
#define unlock_fpu_owner() ({ pagefault_enable(); preempt_enable(); })
/* Assembly functions to move context to/from the FPU */
extern asmlinkage int
_save_fp_context(void __user *fpregs, void __user *fcc, void __user *csr);
extern asmlinkage int
_restore_fp_context(void __user *fpregs, void __user *fcc, void __user *csr);
struct rt_sigframe {
struct siginfo rs_info;
struct ucontext rs_uctx;
};
struct _ctx_layout {
struct sctx_info *addr;
unsigned int size;
};
struct extctx_layout {
unsigned long size;
unsigned int flags;
struct _ctx_layout fpu;
struct _ctx_layout end;
};
static void __user *get_ctx_through_ctxinfo(struct sctx_info *info)
{
return (void __user *)((char *)info + sizeof(struct sctx_info));
}
/*
* Thread saved context copy to/from a signal context presumed to be on the
* user stack, and therefore accessed with appropriate macros from uaccess.h.
*/
static int copy_fpu_to_sigcontext(struct fpu_context __user *ctx)
{
int i;
int err = 0;
uint64_t __user *regs = (uint64_t *)&ctx->regs;
uint64_t __user *fcc = &ctx->fcc;
uint32_t __user *fcsr = &ctx->fcsr;
for (i = 0; i < NUM_FPU_REGS; i++) {
err |=
__put_user(get_fpr64(&current->thread.fpu.fpr[i], 0),
&regs[i]);
}
err |= __put_user(current->thread.fpu.fcc, fcc);
err |= __put_user(current->thread.fpu.fcsr, fcsr);
return err;
}
static int copy_fpu_from_sigcontext(struct fpu_context __user *ctx)
{
int i;
int err = 0;
u64 fpr_val;
uint64_t __user *regs = (uint64_t *)&ctx->regs;
uint64_t __user *fcc = &ctx->fcc;
uint32_t __user *fcsr = &ctx->fcsr;
for (i = 0; i < NUM_FPU_REGS; i++) {
err |= __get_user(fpr_val, &regs[i]);
set_fpr64(&current->thread.fpu.fpr[i], 0, fpr_val);
}
err |= __get_user(current->thread.fpu.fcc, fcc);
err |= __get_user(current->thread.fpu.fcsr, fcsr);
return err;
}
/*
* Wrappers for the assembly _{save,restore}_fp_context functions.
*/
static int save_hw_fpu_context(struct fpu_context __user *ctx)
{
uint64_t __user *regs = (uint64_t *)&ctx->regs;
uint64_t __user *fcc = &ctx->fcc;
uint32_t __user *fcsr = &ctx->fcsr;
return _save_fp_context(regs, fcc, fcsr);
}
static int restore_hw_fpu_context(struct fpu_context __user *ctx)
{
uint64_t __user *regs = (uint64_t *)&ctx->regs;
uint64_t __user *fcc = &ctx->fcc;
uint32_t __user *fcsr = &ctx->fcsr;
return _restore_fp_context(regs, fcc, fcsr);
}
static int fcsr_pending(unsigned int __user *fcsr)
{
int err, sig = 0;
unsigned int csr, enabled;
err = __get_user(csr, fcsr);
enabled = ((csr & FPU_CSR_ALL_E) << 24);
/*
* If the signal handler set some FPU exceptions, clear it and
* send SIGFPE.
*/
if (csr & enabled) {
csr &= ~enabled;
err |= __put_user(csr, fcsr);
sig = SIGFPE;
}
return err ?: sig;
}
/*
* Helper routines
*/
static int protected_save_fpu_context(struct extctx_layout *extctx)
{
int err = 0;
struct sctx_info __user *info = extctx->fpu.addr;
struct fpu_context __user *fpu_ctx = (struct fpu_context *)get_ctx_through_ctxinfo(info);
uint64_t __user *regs = (uint64_t *)&fpu_ctx->regs;
uint64_t __user *fcc = &fpu_ctx->fcc;
uint32_t __user *fcsr = &fpu_ctx->fcsr;
while (1) {
lock_fpu_owner();
if (is_fpu_owner())
err = save_hw_fpu_context(fpu_ctx);
else
err = copy_fpu_to_sigcontext(fpu_ctx);
unlock_fpu_owner();
err |= __put_user(FPU_CTX_MAGIC, &info->magic);
err |= __put_user(extctx->fpu.size, &info->size);
if (likely(!err))
break;
/* Touch the FPU context and try again */
err = __put_user(0, &regs[0]) |
__put_user(0, &regs[31]) |
__put_user(0, fcc) |
__put_user(0, fcsr);
if (err)
return err; /* really bad sigcontext */
}
return err;
}
static int protected_restore_fpu_context(struct extctx_layout *extctx)
{
int err = 0, sig = 0, tmp __maybe_unused;
struct sctx_info __user *info = extctx->fpu.addr;
struct fpu_context __user *fpu_ctx = (struct fpu_context *)get_ctx_through_ctxinfo(info);
uint64_t __user *regs = (uint64_t *)&fpu_ctx->regs;
uint64_t __user *fcc = &fpu_ctx->fcc;
uint32_t __user *fcsr = &fpu_ctx->fcsr;
err = sig = fcsr_pending(fcsr);
if (err < 0)
return err;
while (1) {
lock_fpu_owner();
if (is_fpu_owner())
err = restore_hw_fpu_context(fpu_ctx);
else
err = copy_fpu_from_sigcontext(fpu_ctx);
unlock_fpu_owner();
if (likely(!err))
break;
/* Touch the FPU context and try again */
err = __get_user(tmp, &regs[0]) |
__get_user(tmp, &regs[31]) |
__get_user(tmp, fcc) |
__get_user(tmp, fcsr);
if (err)
break; /* really bad sigcontext */
}
return err ?: sig;
}
static int setup_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc,
struct extctx_layout *extctx)
{
int i, err = 0;
struct sctx_info __user *info;
err |= __put_user(regs->csr_era, &sc->sc_pc);
err |= __put_user(extctx->flags, &sc->sc_flags);
err |= __put_user(0, &sc->sc_regs[0]);
for (i = 1; i < 32; i++)
err |= __put_user(regs->regs[i], &sc->sc_regs[i]);
if (extctx->fpu.addr)
err |= protected_save_fpu_context(extctx);
/* Set the "end" magic */
info = (struct sctx_info *)extctx->end.addr;
err |= __put_user(0, &info->magic);
err |= __put_user(0, &info->size);
return err;
}
static int parse_extcontext(struct sigcontext __user *sc, struct extctx_layout *extctx)
{
int err = 0;
unsigned int magic, size;
struct sctx_info __user *info = (struct sctx_info __user *)&sc->sc_extcontext;
while(1) {
err |= __get_user(magic, &info->magic);
err |= __get_user(size, &info->size);
if (err)
return err;
switch (magic) {
case 0: /* END */
goto done;
case FPU_CTX_MAGIC:
if (size < (sizeof(struct sctx_info) +
sizeof(struct fpu_context)))
goto invalid;
extctx->fpu.addr = info;
break;
default:
goto invalid;
}
info = (struct sctx_info *)((char *)info + size);
}
done:
return 0;
invalid:
return -EINVAL;
}
static int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
{
int i, err = 0;
struct extctx_layout extctx;
memset(&extctx, 0, sizeof(struct extctx_layout));
err = __get_user(extctx.flags, &sc->sc_flags);
if (err)
goto bad;
err = parse_extcontext(sc, &extctx);
if (err)
goto bad;
conditional_used_math(extctx.flags & SC_USED_FP);
/*
* The signal handler may have used FPU; give it up if the program
* doesn't want it following sigreturn.
*/
if (!(extctx.flags & SC_USED_FP))
lose_fpu(0);
/* Always make any pending restarted system calls return -EINTR */
current->restart_block.fn = do_no_restart_syscall;
err |= __get_user(regs->csr_era, &sc->sc_pc);
for (i = 1; i < 32; i++)
err |= __get_user(regs->regs[i], &sc->sc_regs[i]);
if (extctx.fpu.addr)
err |= protected_restore_fpu_context(&extctx);
bad:
return err;
}
static unsigned int handle_flags(void)
{
unsigned int flags = 0;
flags = used_math() ? SC_USED_FP : 0;
switch (current->thread.error_code) {
case 1:
flags |= SC_ADDRERR_RD;
break;
case 2:
flags |= SC_ADDRERR_WR;
break;
}
return flags;
}
static unsigned long extframe_alloc(struct extctx_layout *extctx,
struct _ctx_layout *layout,
size_t size, unsigned int align, unsigned long base)
{
unsigned long new_base = base - size;
new_base = round_down(new_base, (align < 16 ? 16 : align));
new_base -= sizeof(struct sctx_info);
layout->addr = (void *)new_base;
layout->size = (unsigned int)(base - new_base);
extctx->size += layout->size;
return new_base;
}
static unsigned long setup_extcontext(struct extctx_layout *extctx, unsigned long sp)
{
unsigned long new_sp = sp;
memset(extctx, 0, sizeof(struct extctx_layout));
extctx->flags = handle_flags();
/* Grow down, alloc "end" context info first. */
new_sp -= sizeof(struct sctx_info);
extctx->end.addr = (void *)new_sp;
extctx->end.size = (unsigned int)sizeof(struct sctx_info);
extctx->size += extctx->end.size;
if (extctx->flags & SC_USED_FP) {
if (cpu_has_fpu)
new_sp = extframe_alloc(extctx, &extctx->fpu,
sizeof(struct fpu_context), FPU_CTX_ALIGN, new_sp);
}
return new_sp;
}
void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs,
struct extctx_layout *extctx)
{
unsigned long sp;
/* Default to using normal stack */
sp = regs->regs[3];
/*
* If we are on the alternate signal stack and would overflow it, don't.
* Return an always-bogus address instead so we will die with SIGSEGV.
*/
if (on_sig_stack(sp) &&
!likely(on_sig_stack(sp - sizeof(struct rt_sigframe))))
return (void __user __force *)(-1UL);
sp = sigsp(sp, ksig);
sp = round_down(sp, 16);
sp = setup_extcontext(extctx, sp);
sp -= sizeof(struct rt_sigframe);
if (!IS_ALIGNED(sp, 16))
BUG();
return (void __user *)sp;
}
/*
* Atomically swap in the new signal mask, and wait for a signal.
*/
asmlinkage long sys_rt_sigreturn(void)
{
int sig;
sigset_t set;
struct pt_regs *regs;
struct rt_sigframe __user *frame;
regs = current_pt_regs();
frame = (struct rt_sigframe __user *)regs->regs[3];
if (!access_ok(frame, sizeof(*frame)))
goto badframe;
if (__copy_from_user(&set, &frame->rs_uctx.uc_sigmask, sizeof(set)))
goto badframe;
set_current_blocked(&set);
sig = restore_sigcontext(regs, &frame->rs_uctx.uc_mcontext);
if (sig < 0)
goto badframe;
else if (sig)
force_sig(sig);
regs->regs[0] = 0; /* No syscall restarting */
if (restore_altstack(&frame->rs_uctx.uc_stack))
goto badframe;
return regs->regs[4];
badframe:
force_sig(SIGSEGV);
return 0;
}
static int setup_rt_frame(void *sig_return, struct ksignal *ksig,
struct pt_regs *regs, sigset_t *set)
{
int err = 0;
struct extctx_layout extctx;
struct rt_sigframe __user *frame;
frame = get_sigframe(ksig, regs, &extctx);
if (!access_ok(frame, sizeof(*frame) + extctx.size))
return -EFAULT;
/* Create siginfo. */
err |= copy_siginfo_to_user(&frame->rs_info, &ksig->info);
/* Create the ucontext. */
err |= __put_user(0, &frame->rs_uctx.uc_flags);
err |= __put_user(NULL, &frame->rs_uctx.uc_link);
err |= __save_altstack(&frame->rs_uctx.uc_stack, regs->regs[3]);
err |= setup_sigcontext(regs, &frame->rs_uctx.uc_mcontext, &extctx);
err |= __copy_to_user(&frame->rs_uctx.uc_sigmask, set, sizeof(*set));
if (err)
return -EFAULT;
/*
* Arguments to signal handler:
*
* a0 = signal number
* a1 = pointer to siginfo
* a2 = pointer to ucontext
*
* c0_era point to the signal handler, $r3 (sp) points to
* the struct rt_sigframe.
*/
regs->regs[4] = ksig->sig;
regs->regs[5] = (unsigned long) &frame->rs_info;
regs->regs[6] = (unsigned long) &frame->rs_uctx;
regs->regs[3] = (unsigned long) frame;
regs->regs[1] = (unsigned long) sig_return;
regs->csr_era = (unsigned long) ksig->ka.sa.sa_handler;
DEBUGP("SIG deliver (%s:%d): sp=0x%p pc=0x%lx ra=0x%lx\n",
current->comm, current->pid,
frame, regs->csr_era, regs->regs[1]);
return 0;
}
static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
{
int ret;
sigset_t *oldset = sigmask_to_save();
void *vdso = current->mm->context.vdso;
/* Are we from a system call? */
if (regs->regs[0]) {
switch (regs->regs[4]) {
case -ERESTART_RESTARTBLOCK:
case -ERESTARTNOHAND:
regs->regs[4] = -EINTR;
break;
case -ERESTARTSYS:
if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
regs->regs[4] = -EINTR;
break;
}
fallthrough;
case -ERESTARTNOINTR:
regs->regs[4] = regs->orig_a0;
regs->csr_era -= 4;
}
regs->regs[0] = 0; /* Don't deal with this again. */
}
rseq_signal_deliver(ksig, regs);
ret = setup_rt_frame(vdso + current->thread.vdso->offset_sigreturn, ksig, regs, oldset);
signal_setup_done(ret, ksig, 0);
}
void arch_do_signal_or_restart(struct pt_regs *regs, bool has_signal)
{
struct ksignal ksig;
if (has_signal && get_signal(&ksig)) {
/* Whee! Actually deliver the signal. */
handle_signal(&ksig, regs);
return;
}
/* Are we from a system call? */
if (regs->regs[0]) {
switch (regs->regs[4]) {
case -ERESTARTNOHAND:
case -ERESTARTSYS:
case -ERESTARTNOINTR:
regs->regs[4] = regs->orig_a0;
regs->csr_era -= 4;
break;
case -ERESTART_RESTARTBLOCK:
regs->regs[4] = regs->orig_a0;
regs->regs[11] = __NR_restart_syscall;
regs->csr_era -= 4;
break;
}
regs->regs[0] = 0; /* Don't deal with this again. */
}
/*
* If there's no signal to deliver, we just put the saved sigmask
* back
*/
restore_saved_sigmask();
}
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