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linuxdebug/arch/parisc/kernel/signal.c

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// SPDX-License-Identifier: GPL-2.0
/*
* PA-RISC architecture-specific signal handling support.
*
* Copyright (C) 2000 David Huggins-Daines <dhd@debian.org>
* Copyright (C) 2000 Linuxcare, Inc.
* Copyright (C) 2000-2022 Helge Deller <deller@gmx.de>
* Copyright (C) 2022 John David Anglin <dave.anglin@bell.net>
*
* Based on the ia64, i386, and alpha versions.
*/
#include <linux/sched.h>
#include <linux/sched/debug.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/ptrace.h>
#include <linux/resume_user_mode.h>
#include <linux/unistd.h>
#include <linux/stddef.h>
#include <linux/compat.h>
#include <linux/elf.h>
#include <asm/ucontext.h>
#include <asm/rt_sigframe.h>
#include <linux/uaccess.h>
#include <asm/cacheflush.h>
#include <asm/asm-offsets.h>
#include <asm/vdso.h>
#ifdef CONFIG_COMPAT
#include "signal32.h"
#endif
#define DEBUG_SIG 0
#define DEBUG_SIG_LEVEL 2
#if DEBUG_SIG
#define DBG(LEVEL, ...) \
((DEBUG_SIG_LEVEL >= LEVEL) \
? printk(__VA_ARGS__) : (void) 0)
#else
#define DBG(LEVEL, ...)
#endif
/* gcc will complain if a pointer is cast to an integer of different
* size. If you really need to do this (and we do for an ELF32 user
* application in an ELF64 kernel) then you have to do a cast to an
* integer of the same size first. The A() macro accomplishes
* this. */
#define A(__x) ((unsigned long)(__x))
/*
* Do a signal return - restore sigcontext.
*/
static long
restore_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs)
{
long err = 0;
err |= __copy_from_user(regs->gr, sc->sc_gr, sizeof(regs->gr));
err |= __copy_from_user(regs->fr, sc->sc_fr, sizeof(regs->fr));
err |= __copy_from_user(regs->iaoq, sc->sc_iaoq, sizeof(regs->iaoq));
err |= __copy_from_user(regs->iasq, sc->sc_iasq, sizeof(regs->iasq));
err |= __get_user(regs->sar, &sc->sc_sar);
DBG(2, "%s: iaoq is %#lx / %#lx\n",
__func__, regs->iaoq[0], regs->iaoq[1]);
DBG(2, "%s: r28 is %ld\n", __func__, regs->gr[28]);
return err;
}
void
sys_rt_sigreturn(struct pt_regs *regs, int in_syscall)
{
struct rt_sigframe __user *frame;
sigset_t set;
unsigned long usp = (regs->gr[30] & ~(0x01UL));
unsigned long sigframe_size = PARISC_RT_SIGFRAME_SIZE;
#ifdef CONFIG_64BIT
struct compat_rt_sigframe __user * compat_frame;
if (is_compat_task())
sigframe_size = PARISC_RT_SIGFRAME_SIZE32;
#endif
current->restart_block.fn = do_no_restart_syscall;
/* Unwind the user stack to get the rt_sigframe structure. */
frame = (struct rt_sigframe __user *)
(usp - sigframe_size);
DBG(2, "%s: frame is %p pid %d\n", __func__, frame, task_pid_nr(current));
regs->orig_r28 = 1; /* no restarts for sigreturn */
#ifdef CONFIG_64BIT
compat_frame = (struct compat_rt_sigframe __user *)frame;
if (is_compat_task()) {
if (get_compat_sigset(&set, &compat_frame->uc.uc_sigmask))
goto give_sigsegv;
} else
#endif
{
if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
goto give_sigsegv;
}
set_current_blocked(&set);
/* Good thing we saved the old gr[30], eh? */
#ifdef CONFIG_64BIT
if (is_compat_task()) {
DBG(1, "%s: compat_frame->uc.uc_mcontext 0x%p\n",
__func__, &compat_frame->uc.uc_mcontext);
// FIXME: Load upper half from register file
if (restore_sigcontext32(&compat_frame->uc.uc_mcontext,
&compat_frame->regs, regs))
goto give_sigsegv;
DBG(1, "%s: usp %#08lx stack 0x%p\n",
__func__, usp, &compat_frame->uc.uc_stack);
if (compat_restore_altstack(&compat_frame->uc.uc_stack))
goto give_sigsegv;
} else
#endif
{
DBG(1, "%s: frame->uc.uc_mcontext 0x%p\n",
__func__, &frame->uc.uc_mcontext);
if (restore_sigcontext(&frame->uc.uc_mcontext, regs))
goto give_sigsegv;
DBG(1, "%s: usp %#08lx stack 0x%p\n",
__func__, usp, &frame->uc.uc_stack);
if (restore_altstack(&frame->uc.uc_stack))
goto give_sigsegv;
}
/* If we are on the syscall path IAOQ will not be restored, and
* if we are on the interrupt path we must not corrupt gr31.
*/
if (in_syscall)
regs->gr[31] = regs->iaoq[0];
return;
give_sigsegv:
DBG(1, "%s: Sending SIGSEGV\n", __func__);
force_sig(SIGSEGV);
return;
}
/*
* Set up a signal frame.
*/
static inline void __user *
get_sigframe(struct k_sigaction *ka, unsigned long sp, size_t frame_size)
{
/*FIXME: ELF32 vs. ELF64 has different frame_size, but since we
don't use the parameter it doesn't matter */
DBG(1, "%s: ka = %#lx, sp = %#lx, frame_size = %zu\n",
__func__, (unsigned long)ka, sp, frame_size);
/* Align alternate stack and reserve 64 bytes for the signal
handler's frame marker. */
if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && ! sas_ss_flags(sp))
sp = (current->sas_ss_sp + 0x7f) & ~0x3f; /* Stacks grow up! */
DBG(1, "%s: Returning sp = %#lx\n", __func__, (unsigned long)sp);
return (void __user *) sp; /* Stacks grow up. Fun. */
}
static long
setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, int in_syscall)
{
unsigned long flags = 0;
long err = 0;
if (on_sig_stack((unsigned long) sc))
flags |= PARISC_SC_FLAG_ONSTACK;
if (in_syscall) {
flags |= PARISC_SC_FLAG_IN_SYSCALL;
/* regs->iaoq is undefined in the syscall return path */
err |= __put_user(regs->gr[31], &sc->sc_iaoq[0]);
err |= __put_user(regs->gr[31]+4, &sc->sc_iaoq[1]);
err |= __put_user(regs->sr[3], &sc->sc_iasq[0]);
err |= __put_user(regs->sr[3], &sc->sc_iasq[1]);
DBG(1, "%s: iaoq %#lx / %#lx (in syscall)\n",
__func__, regs->gr[31], regs->gr[31]+4);
} else {
err |= __copy_to_user(sc->sc_iaoq, regs->iaoq, sizeof(regs->iaoq));
err |= __copy_to_user(sc->sc_iasq, regs->iasq, sizeof(regs->iasq));
DBG(1, "%s: iaoq %#lx / %#lx (not in syscall)\n",
__func__, regs->iaoq[0], regs->iaoq[1]);
}
err |= __put_user(flags, &sc->sc_flags);
err |= __copy_to_user(sc->sc_gr, regs->gr, sizeof(regs->gr));
err |= __copy_to_user(sc->sc_fr, regs->fr, sizeof(regs->fr));
err |= __put_user(regs->sar, &sc->sc_sar);
DBG(1, "%s: r28 is %ld\n", __func__, regs->gr[28]);
return err;
}
static long
setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs,
int in_syscall)
{
struct rt_sigframe __user *frame;
unsigned long rp, usp;
unsigned long haddr, sigframe_size;
unsigned long start;
int err = 0;
#ifdef CONFIG_64BIT
struct compat_rt_sigframe __user * compat_frame;
#endif
usp = (regs->gr[30] & ~(0x01UL));
sigframe_size = PARISC_RT_SIGFRAME_SIZE;
#ifdef CONFIG_64BIT
if (is_compat_task()) {
/* The gcc alloca implementation leaves garbage in the upper 32 bits of sp */
usp = (compat_uint_t)usp;
sigframe_size = PARISC_RT_SIGFRAME_SIZE32;
}
#endif
frame = get_sigframe(&ksig->ka, usp, sigframe_size);
DBG(1, "%s: frame %p info %p\n", __func__, frame, &ksig->info);
start = (unsigned long) frame;
if (start >= TASK_SIZE_MAX - sigframe_size)
return -EFAULT;
#ifdef CONFIG_64BIT
compat_frame = (struct compat_rt_sigframe __user *)frame;
if (is_compat_task()) {
DBG(1, "%s: frame->info = 0x%p\n", __func__, &compat_frame->info);
err |= copy_siginfo_to_user32(&compat_frame->info, &ksig->info);
err |= __compat_save_altstack( &compat_frame->uc.uc_stack, regs->gr[30]);
DBG(1, "%s: frame->uc = 0x%p\n", __func__, &compat_frame->uc);
DBG(1, "%s: frame->uc.uc_mcontext = 0x%p\n",
__func__, &compat_frame->uc.uc_mcontext);
err |= setup_sigcontext32(&compat_frame->uc.uc_mcontext,
&compat_frame->regs, regs, in_syscall);
err |= put_compat_sigset(&compat_frame->uc.uc_sigmask, set,
sizeof(compat_sigset_t));
} else
#endif
{
DBG(1, "%s: frame->info = 0x%p\n", __func__, &frame->info);
err |= copy_siginfo_to_user(&frame->info, &ksig->info);
err |= __save_altstack(&frame->uc.uc_stack, regs->gr[30]);
DBG(1, "%s: frame->uc = 0x%p\n", __func__, &frame->uc);
DBG(1, "%s: frame->uc.uc_mcontext = 0x%p\n",
__func__, &frame->uc.uc_mcontext);
err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, in_syscall);
/* FIXME: Should probably be converted as well for the compat case */
err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
}
if (err)
return -EFAULT;
#ifdef CONFIG_64BIT
if (!is_compat_task())
rp = VDSO64_SYMBOL(current, sigtramp_rt);
else
#endif
rp = VDSO32_SYMBOL(current, sigtramp_rt);
if (in_syscall)
rp += 4*4; /* skip 4 instructions and start at ldi 1,%r25 */
haddr = A(ksig->ka.sa.sa_handler);
/* The sa_handler may be a pointer to a function descriptor */
#ifdef CONFIG_64BIT
if (is_compat_task()) {
#endif
if (haddr & PA_PLABEL_FDESC) {
Elf32_Fdesc fdesc;
Elf32_Fdesc __user *ufdesc = (Elf32_Fdesc __user *)A(haddr & ~3);
err = __copy_from_user(&fdesc, ufdesc, sizeof(fdesc));
if (err)
return -EFAULT;
haddr = fdesc.addr;
regs->gr[19] = fdesc.gp;
}
#ifdef CONFIG_64BIT
} else {
Elf64_Fdesc fdesc;
Elf64_Fdesc __user *ufdesc = (Elf64_Fdesc __user *)A(haddr & ~3);
err = __copy_from_user(&fdesc, ufdesc, sizeof(fdesc));
if (err)
return -EFAULT;
haddr = fdesc.addr;
regs->gr[19] = fdesc.gp;
DBG(1, "%s: 64 bit signal, exe=%#lx, r19=%#lx, in_syscall=%d\n",
__func__, haddr, regs->gr[19], in_syscall);
}
#endif
/* The syscall return path will create IAOQ values from r31.
*/
if (in_syscall) {
regs->gr[31] = haddr;
#ifdef CONFIG_64BIT
if (!test_thread_flag(TIF_32BIT))
sigframe_size |= 1; /* XXX ???? */
#endif
} else {
unsigned long psw = USER_PSW;
#ifdef CONFIG_64BIT
if (!test_thread_flag(TIF_32BIT))
psw |= PSW_W;
#endif
/* If we are singlestepping, arrange a trap to be delivered
when we return to userspace. Note the semantics -- we
should trap before the first insn in the handler is
executed. Ref:
http://sources.redhat.com/ml/gdb/2004-11/msg00245.html
*/
if (pa_psw(current)->r) {
pa_psw(current)->r = 0;
psw |= PSW_R;
mtctl(-1, 0);
}
regs->gr[0] = psw;
regs->iaoq[0] = haddr | PRIV_USER;
regs->iaoq[1] = regs->iaoq[0] + 4;
}
regs->gr[2] = rp; /* userland return pointer */
regs->gr[26] = ksig->sig; /* signal number */
#ifdef CONFIG_64BIT
if (is_compat_task()) {
regs->gr[25] = A(&compat_frame->info); /* siginfo pointer */
regs->gr[24] = A(&compat_frame->uc); /* ucontext pointer */
} else
#endif
{
regs->gr[25] = A(&frame->info); /* siginfo pointer */
regs->gr[24] = A(&frame->uc); /* ucontext pointer */
}
DBG(1, "%s: making sigreturn frame: %#lx + %#lx = %#lx\n", __func__,
regs->gr[30], sigframe_size,
regs->gr[30] + sigframe_size);
/* Raise the user stack pointer to make a proper call frame. */
regs->gr[30] = (A(frame) + sigframe_size);
DBG(1, "%s: sig deliver (%s,%d) frame=0x%p sp=%#lx iaoq=%#lx/%#lx rp=%#lx\n",
__func__, current->comm, current->pid, frame, regs->gr[30],
regs->iaoq[0], regs->iaoq[1], rp);
return 0;
}
/*
* OK, we're invoking a handler.
*/
static void
handle_signal(struct ksignal *ksig, struct pt_regs *regs, int in_syscall)
{
int ret;
sigset_t *oldset = sigmask_to_save();
DBG(1, "%s: sig=%d, ka=%p, info=%p, oldset=%p, regs=%p\n",
__func__, ksig->sig, &ksig->ka, &ksig->info, oldset, regs);
/* Set up the stack frame */
ret = setup_rt_frame(ksig, oldset, regs, in_syscall);
signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP) ||
test_thread_flag(TIF_BLOCKSTEP));
DBG(1, "%s: Exit (success), regs->gr[28] = %ld\n",
__func__, regs->gr[28]);
}
/*
* Check how the syscall number gets loaded into %r20 within
* the delay branch in userspace and adjust as needed.
*/
static void check_syscallno_in_delay_branch(struct pt_regs *regs)
{
u32 opcode, source_reg;
u32 __user *uaddr;
int err;
/* Usually we don't have to restore %r20 (the system call number)
* because it gets loaded in the delay slot of the branch external
* instruction via the ldi instruction.
* In some cases a register-to-register copy instruction might have
* been used instead, in which case we need to copy the syscall
* number into the source register before returning to userspace.
*/
/* A syscall is just a branch, so all we have to do is fiddle the
* return pointer so that the ble instruction gets executed again.
*/
regs->gr[31] -= 8; /* delayed branching */
/* Get assembler opcode of code in delay branch */
uaddr = (unsigned int *) ((regs->gr[31] & ~3) + 4);
err = get_user(opcode, uaddr);
if (err)
return;
/* Check if delay branch uses "ldi int,%r20" */
if ((opcode & 0xffff0000) == 0x34140000)
return; /* everything ok, just return */
/* Check if delay branch uses "nop" */
if (opcode == INSN_NOP)
return;
/* Check if delay branch uses "copy %rX,%r20" */
if ((opcode & 0xffe0ffff) == 0x08000254) {
source_reg = (opcode >> 16) & 31;
regs->gr[source_reg] = regs->gr[20];
return;
}
pr_warn("syscall restart: %s (pid %d): unexpected opcode 0x%08x\n",
current->comm, task_pid_nr(current), opcode);
}
static inline void
syscall_restart(struct pt_regs *regs, struct k_sigaction *ka)
{
if (regs->orig_r28)
return;
regs->orig_r28 = 1; /* no more restarts */
DBG(1, "%s: orig_r28 = %ld pid %d r20 %ld\n",
__func__, regs->orig_r28, task_pid_nr(current), regs->gr[20]);
/* Check the return code */
switch (regs->gr[28]) {
case -ERESTART_RESTARTBLOCK:
case -ERESTARTNOHAND:
DBG(1, "%s: ERESTARTNOHAND: returning -EINTR\n", __func__);
regs->gr[28] = -EINTR;
break;
case -ERESTARTSYS:
if (!(ka->sa.sa_flags & SA_RESTART)) {
DBG(1, "%s: ERESTARTSYS: putting -EINTR pid %d\n",
__func__, task_pid_nr(current));
regs->gr[28] = -EINTR;
break;
}
fallthrough;
case -ERESTARTNOINTR:
DBG(1, "%s: %ld\n", __func__, regs->gr[28]);
check_syscallno_in_delay_branch(regs);
break;
}
}
static inline void
insert_restart_trampoline(struct pt_regs *regs)
{
if (regs->orig_r28)
return;
regs->orig_r28 = 1; /* no more restarts */
DBG(2, "%s: gr28 = %ld pid %d\n",
__func__, regs->gr[28], task_pid_nr(current));
switch (regs->gr[28]) {
case -ERESTART_RESTARTBLOCK: {
/* Restart the system call - no handlers present */
unsigned int *usp = (unsigned int *)regs->gr[30];
unsigned long rp;
long err = 0;
/* check that we don't exceed the stack */
if (A(&usp[0]) >= TASK_SIZE_MAX - 5 * sizeof(int))
return;
/* Call trampoline in vdso to restart the syscall
* with __NR_restart_syscall.
* Original return addresses are on stack like this:
*
* 0: <return address (orig r31)>
* 4: <2nd half for 64-bit>
*/
#ifdef CONFIG_64BIT
if (!is_compat_task()) {
err |= put_user(regs->gr[31] >> 32, &usp[0]);
err |= put_user(regs->gr[31] & 0xffffffff, &usp[1]);
rp = VDSO64_SYMBOL(current, restart_syscall);
} else
#endif
{
err |= put_user(regs->gr[31], &usp[0]);
rp = VDSO32_SYMBOL(current, restart_syscall);
}
WARN_ON(err);
regs->gr[31] = rp;
DBG(1, "%s: ERESTART_RESTARTBLOCK\n", __func__);
return;
}
case -EINTR:
/* ok, was handled before and should be returned. */
break;
case -ERESTARTNOHAND:
case -ERESTARTSYS:
case -ERESTARTNOINTR:
DBG(1, "%s: Type %ld\n", __func__, regs->gr[28]);
check_syscallno_in_delay_branch(regs);
return;
default:
break;
}
}
/*
* We need to be able to restore the syscall arguments (r21-r26) to
* restart syscalls. Thus, the syscall path should save them in the
* pt_regs structure (it's okay to do so since they are caller-save
* registers). As noted below, the syscall number gets restored for
* us due to the magic of delayed branching.
*/
static void do_signal(struct pt_regs *regs, long in_syscall)
{
struct ksignal ksig;
int restart_syscall;
bool has_handler;
has_handler = get_signal(&ksig);
restart_syscall = 0;
if (in_syscall)
restart_syscall = 1;
if (has_handler) {
/* Restart a system call if necessary. */
if (restart_syscall)
syscall_restart(regs, &ksig.ka);
handle_signal(&ksig, regs, in_syscall);
DBG(1, "%s: Handled signal pid %d\n",
__func__, task_pid_nr(current));
return;
}
/* Do we need to restart the system call? */
if (restart_syscall)
insert_restart_trampoline(regs);
DBG(1, "%s: Exit (not delivered), regs->gr[28] = %ld orig_r28 = %ld pid %d\n",
__func__, regs->gr[28], regs->orig_r28, task_pid_nr(current));
restore_saved_sigmask();
}
void do_notify_resume(struct pt_regs *regs, long in_syscall)
{
if (test_thread_flag(TIF_SIGPENDING) ||
test_thread_flag(TIF_NOTIFY_SIGNAL))
do_signal(regs, in_syscall);
if (test_thread_flag(TIF_NOTIFY_RESUME))
resume_user_mode_work(regs);
}
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