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linux/arch/parisc/kernel/signal.c

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// SPDX-License-Identifier: GPL-2.0
/*
* linux/arch/parisc/kernel/signal.c: Architecture-specific signal
* handling support.
*
* Copyright (C) 2000 David Huggins-Daines <dhd@debian.org>
* Copyright (C) 2000 Linuxcare, Inc.
*
* Based on the ia64, i386, and alpha versions.
*
* Like the IA-64, we are a recent enough port (we are *starting*
* with glibc2.2) that we do not need to support the old non-realtime
* Linux signals. Therefore we don't.
*/
#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/tracehook.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/pgalloc.h>
#include <asm/cacheflush.h>
#include <asm/asm-offsets.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.
*/
/* Trampoline for calling rt_sigreturn() */
#define INSN_LDI_R25_0 0x34190000 /* ldi 0,%r25 (in_syscall=0) */
#define INSN_LDI_R25_1 0x34190002 /* ldi 1,%r25 (in_syscall=1) */
#define INSN_LDI_R20 0x3414015a /* ldi __NR_rt_sigreturn,%r20 */
#define INSN_BLE_SR2_R0 0xe4008200 /* be,l 0x100(%sr2,%r0),%sr0,%r31 */
/* For debugging */
#define INSN_DIE_HORRIBLY 0x68000ccc /* stw %r0,0x666(%sr0,%r0) */
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,"restore_sigcontext: iaoq is %#lx / %#lx\n",
regs->iaoq[0],regs->iaoq[1]);
DBG(2,"restore_sigcontext: r28 is %ld\n", 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,"sys_rt_sigreturn: frame is %p\n", frame);
regs->orig_r28 = 1; /* no restarts for sigreturn */
#ifdef CONFIG_64BIT
compat_frame = (struct compat_rt_sigframe __user *)frame;
if (is_compat_task()) {
DBG(2,"sys_rt_sigreturn: ELF32 process.\n");
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,"sys_rt_sigreturn: compat_frame->uc.uc_mcontext 0x%p\n",
&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,"sys_rt_sigreturn: usp %#08lx stack 0x%p\n",
usp, &compat_frame->uc.uc_stack);
if (compat_restore_altstack(&compat_frame->uc.uc_stack))
goto give_sigsegv;
} else
#endif
{
DBG(1,"sys_rt_sigreturn: frame->uc.uc_mcontext 0x%p\n",
&frame->uc.uc_mcontext);
if (restore_sigcontext(&frame->uc.uc_mcontext, regs))
goto give_sigsegv;
DBG(1,"sys_rt_sigreturn: usp %#08lx stack 0x%p\n",
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];
#if DEBUG_SIG
DBG(1,"sys_rt_sigreturn: returning to %#lx, DUMPING REGS:\n", regs->iaoq[0]);
show_regs(regs);
#endif
return;
give_sigsegv:
DBG(1,"sys_rt_sigreturn: Sending SIGSEGV\n");
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,"get_sigframe: ka = %#lx, sp = %#lx, frame_size = %#lx\n",
(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,"get_sigframe: Returning sp = %#lx\n", (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,"setup_sigcontext: iaoq %#lx / %#lx (in syscall)\n",
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,"setup_sigcontext: iaoq %#lx / %#lx (not in syscall)\n",
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,"setup_sigcontext: r28 is %ld\n", 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, end;
int err = 0;
#ifdef CONFIG_64BIT
struct compat_rt_sigframe __user * compat_frame;
#endif
usp = (regs->gr[30] & ~(0x01UL));
/*FIXME: frame_size parameter is unused, remove it. */
frame = get_sigframe(&ksig->ka, usp, sizeof(*frame));
DBG(1,"SETUP_RT_FRAME: START\n");
DBG(1,"setup_rt_frame: frame %p info %p\n", frame, ksig->info);
#ifdef CONFIG_64BIT
compat_frame = (struct compat_rt_sigframe __user *)frame;
if (is_compat_task()) {
DBG(1,"setup_rt_frame: frame->info = 0x%p\n", &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,"setup_rt_frame: frame->uc = 0x%p\n", &compat_frame->uc);
DBG(1,"setup_rt_frame: frame->uc.uc_mcontext = 0x%p\n", &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,"setup_rt_frame: frame->info = 0x%p\n", &frame->info);
err |= copy_siginfo_to_user(&frame->info, &ksig->info);
err |= __save_altstack(&frame->uc.uc_stack, regs->gr[30]);
DBG(1,"setup_rt_frame: frame->uc = 0x%p\n", &frame->uc);
DBG(1,"setup_rt_frame: frame->uc.uc_mcontext = 0x%p\n", &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;
/* Set up to return from userspace. If provided, use a stub
already in userspace. The first words of tramp are used to
save the previous sigrestartblock trampoline that might be
on the stack. We start the sigreturn trampoline at
SIGRESTARTBLOCK_TRAMP+X. */
err |= __put_user(in_syscall ? INSN_LDI_R25_1 : INSN_LDI_R25_0,
&frame->tramp[SIGRESTARTBLOCK_TRAMP+0]);
err |= __put_user(INSN_LDI_R20,
&frame->tramp[SIGRESTARTBLOCK_TRAMP+1]);
err |= __put_user(INSN_BLE_SR2_R0,
&frame->tramp[SIGRESTARTBLOCK_TRAMP+2]);
err |= __put_user(INSN_NOP, &frame->tramp[SIGRESTARTBLOCK_TRAMP+3]);
#if DEBUG_SIG
/* Assert that we're flushing in the correct space... */
{
unsigned long sid;
asm ("mfsp %%sr3,%0" : "=r" (sid));
DBG(1,"setup_rt_frame: Flushing 64 bytes at space %#x offset %p\n",
sid, frame->tramp);
}
#endif
start = (unsigned long) &frame->tramp[0];
end = (unsigned long) &frame->tramp[TRAMP_SIZE];
flush_user_dcache_range_asm(start, end);
flush_user_icache_range_asm(start, end);
/* TRAMP Words 0-4, Length 5 = SIGRESTARTBLOCK_TRAMP
* TRAMP Words 5-9, Length 4 = SIGRETURN_TRAMP
* So the SIGRETURN_TRAMP is at the end of SIGRESTARTBLOCK_TRAMP
*/
rp = (unsigned long) &frame->tramp[SIGRESTARTBLOCK_TRAMP];
if (err)
return -EFAULT;
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,"setup_rt_frame: 64 bit signal, exe=%#lx, r19=%#lx, in_syscall=%d\n",
haddr, regs->gr[19], in_syscall);
}
#endif
/* The syscall return path will create IAOQ values from r31.
*/
sigframe_size = PARISC_RT_SIGFRAME_SIZE;
#ifdef CONFIG_64BIT
if (is_compat_task())
sigframe_size = PARISC_RT_SIGFRAME_SIZE32;
#endif
if (in_syscall) {
regs->gr[31] = haddr;
#ifdef CONFIG_64BIT
if (!test_thread_flag(TIF_32BIT))
sigframe_size |= 1;
#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 | 3;
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,"setup_rt_frame: making sigreturn frame: %#lx + %#lx = %#lx\n",
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,"setup_rt_frame: sig deliver (%s,%d) frame=0x%p sp=%#lx iaoq=%#lx/%#lx rp=%#lx\n",
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,"handle_signal: sig=%ld, ka=%p, info=%p, oldset=%p, regs=%p\n",
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,KERN_DEBUG "do_signal: Exit (success), regs->gr[28] = %ld\n",
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 */
/* Check the return code */
switch (regs->gr[28]) {
case -ERESTART_RESTARTBLOCK:
case -ERESTARTNOHAND:
DBG(1,"ERESTARTNOHAND: returning -EINTR\n");
regs->gr[28] = -EINTR;
break;
case -ERESTARTSYS:
if (!(ka->sa.sa_flags & SA_RESTART)) {
DBG(1,"ERESTARTSYS: putting -EINTR\n");
regs->gr[28] = -EINTR;
break;
}
/* fallthrough */
case -ERESTARTNOINTR:
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 */
switch(regs->gr[28]) {
case -ERESTART_RESTARTBLOCK: {
/* Restart the system call - no handlers present */
unsigned int *usp = (unsigned int *)regs->gr[30];
unsigned long start = (unsigned long) &usp[2];
unsigned long end = (unsigned long) &usp[5];
long err = 0;
/* Setup a trampoline to restart the syscall
* with __NR_restart_syscall
*
* 0: <return address (orig r31)>
* 4: <2nd half for 64-bit>
* 8: ldw 0(%sp), %r31
* 12: be 0x100(%sr2, %r0)
* 16: ldi __NR_restart_syscall, %r20
*/
#ifdef CONFIG_64BIT
err |= put_user(regs->gr[31] >> 32, &usp[0]);
err |= put_user(regs->gr[31] & 0xffffffff, &usp[1]);
err |= put_user(0x0fc010df, &usp[2]);
#else
err |= put_user(regs->gr[31], &usp[0]);
err |= put_user(0x0fc0109f, &usp[2]);
#endif
err |= put_user(0xe0008200, &usp[3]);
err |= put_user(0x34140000, &usp[4]);
WARN_ON(err);
/* flush data/instruction cache for new insns */
flush_user_dcache_range_asm(start, end);
flush_user_icache_range_asm(start, end);
regs->gr[31] = regs->gr[30] + 8;
return;
}
case -ERESTARTNOHAND:
case -ERESTARTSYS:
case -ERESTARTNOINTR:
check_syscallno_in_delay_branch(regs);
return;
default:
break;
}
}
/*
* Note that 'init' is a special process: it doesn't get signals it doesn't
* want to handle. Thus you cannot kill init even with a SIGKILL even by
* mistake.
*
* 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.
*/
asmlinkage void
do_signal(struct pt_regs *regs, long in_syscall)
{
struct ksignal ksig;
DBG(1,"\ndo_signal: regs=0x%p, sr7 %#lx, in_syscall=%d\n",
regs, regs->sr[7], in_syscall);
if (get_signal(&ksig)) {
DBG(3,"do_signal: signr = %d, regs->gr[28] = %ld\n", signr, regs->gr[28]);
/* Restart a system call if necessary. */
if (in_syscall)
syscall_restart(regs, &ksig.ka);
handle_signal(&ksig, regs, in_syscall);
return;
}
/* Did we come from a system call? */
if (in_syscall)
insert_restart_trampoline(regs);
DBG(1,"do_signal: Exit (not delivered), regs->gr[28] = %ld\n",
regs->gr[28]);
restore_saved_sigmask();
}
void do_notify_resume(struct pt_regs *regs, long in_syscall)
{
if (test_thread_flag(TIF_SIGPENDING))
do_signal(regs, in_syscall);
if (test_thread_flag(TIF_NOTIFY_RESUME)) {
clear_thread_flag(TIF_NOTIFY_RESUME);
tracehook_notify_resume(regs);
}
}
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