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qemu-e2k/linux-user/mips/cpu_loop.c
Mikulas Patocka 6fad9b4bb9 linux-user/mips: fix abort on integer overflow 
QEMU mips userspace emulation crashes with "qemu: unhandled CPU exception
0x15 - aborting" when one of the integer arithmetic instructions detects
an overflow.

This patch fixes it so that it delivers SIGFPE with FPE_INTOVF instead.

Cc: qemu-stable@nongnu.org
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Message-Id: <3ef979a8-3ee1-eb2d-71f7-d788ff88dd11@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2023-10-18 15:32:16 -07:00

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/*
* qemu user cpu loop
*
* Copyright (c) 2003-2008 Fabrice Bellard
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
#include "qemu/osdep.h"
#include "qemu.h"
#include "user-internals.h"
#include "cpu_loop-common.h"
#include "signal-common.h"
#include "elf.h"
#include "internal.h"
#include "fpu_helper.h"
# ifdef TARGET_ABI_MIPSO32
# define MIPS_SYSCALL_NUMBER_UNUSED -1
static const int8_t mips_syscall_args[] = {
#include "syscall-args-o32.c.inc"
};
# endif /* O32 */
/* Break codes */
enum {
BRK_OVERFLOW = 6,
BRK_DIVZERO = 7
};
static void do_tr_or_bp(CPUMIPSState *env, unsigned int code, bool trap)
{
target_ulong pc = env->active_tc.PC;
switch (code) {
case BRK_OVERFLOW:
force_sig_fault(TARGET_SIGFPE, TARGET_FPE_INTOVF, pc);
break;
case BRK_DIVZERO:
force_sig_fault(TARGET_SIGFPE, TARGET_FPE_INTDIV, pc);
break;
default:
if (trap) {
force_sig(TARGET_SIGTRAP);
} else {
force_sig_fault(TARGET_SIGTRAP, TARGET_TRAP_BRKPT, pc);
}
break;
}
}
void cpu_loop(CPUMIPSState *env)
{
CPUState *cs = env_cpu(env);
int trapnr, si_code;
unsigned int code;
abi_long ret;
# ifdef TARGET_ABI_MIPSO32
unsigned int syscall_num;
# endif
for(;;) {
cpu_exec_start(cs);
trapnr = cpu_exec(cs);
cpu_exec_end(cs);
process_queued_cpu_work(cs);
switch(trapnr) {
case EXCP_SYSCALL:
env->active_tc.PC += 4;
# ifdef TARGET_ABI_MIPSO32
syscall_num = env->active_tc.gpr[2] - 4000;
if (syscall_num >= sizeof(mips_syscall_args)) {
/* syscall_num is larger that any defined for MIPS O32 */
ret = -TARGET_ENOSYS;
} else if (mips_syscall_args[syscall_num] ==
MIPS_SYSCALL_NUMBER_UNUSED) {
/* syscall_num belongs to the range not defined for MIPS O32 */
ret = -TARGET_ENOSYS;
} else {
/* syscall_num is valid */
int nb_args;
abi_ulong sp_reg;
abi_ulong arg5 = 0, arg6 = 0, arg7 = 0, arg8 = 0;
nb_args = mips_syscall_args[syscall_num];
sp_reg = env->active_tc.gpr[29];
switch (nb_args) {
/* these arguments are taken from the stack */
case 8:
if ((ret = get_user_ual(arg8, sp_reg + 28)) != 0) {
goto done_syscall;
}
/* fall through */
case 7:
if ((ret = get_user_ual(arg7, sp_reg + 24)) != 0) {
goto done_syscall;
}
/* fall through */
case 6:
if ((ret = get_user_ual(arg6, sp_reg + 20)) != 0) {
goto done_syscall;
}
/* fall through */
case 5:
if ((ret = get_user_ual(arg5, sp_reg + 16)) != 0) {
goto done_syscall;
}
/* fall through */
default:
break;
}
ret = do_syscall(env, env->active_tc.gpr[2],
env->active_tc.gpr[4],
env->active_tc.gpr[5],
env->active_tc.gpr[6],
env->active_tc.gpr[7],
arg5, arg6, arg7, arg8);
}
done_syscall:
# else
ret = do_syscall(env, env->active_tc.gpr[2],
env->active_tc.gpr[4], env->active_tc.gpr[5],
env->active_tc.gpr[6], env->active_tc.gpr[7],
env->active_tc.gpr[8], env->active_tc.gpr[9],
env->active_tc.gpr[10], env->active_tc.gpr[11]);
# endif /* O32 */
if (ret == -QEMU_ERESTARTSYS) {
env->active_tc.PC -= 4;
break;
}
if (ret == -QEMU_ESIGRETURN) {
/* Returning from a successful sigreturn syscall.
Avoid clobbering register state. */
break;
}
if ((abi_ulong)ret >= (abi_ulong)-1133) {
env->active_tc.gpr[7] = 1; /* error flag */
ret = -ret;
} else {
env->active_tc.gpr[7] = 0; /* error flag */
}
env->active_tc.gpr[2] = ret;
break;
case EXCP_CpU:
case EXCP_RI:
case EXCP_DSPDIS:
force_sig(TARGET_SIGILL);
break;
case EXCP_INTERRUPT:
/* just indicate that signals should be handled asap */
break;
case EXCP_DEBUG:
force_sig_fault(TARGET_SIGTRAP, TARGET_TRAP_BRKPT,
env->active_tc.PC);
break;
case EXCP_FPE:
si_code = TARGET_FPE_FLTUNK;
if (GET_FP_CAUSE(env->active_fpu.fcr31) & FP_INVALID) {
si_code = TARGET_FPE_FLTINV;
} else if (GET_FP_CAUSE(env->active_fpu.fcr31) & FP_DIV0) {
si_code = TARGET_FPE_FLTDIV;
} else if (GET_FP_CAUSE(env->active_fpu.fcr31) & FP_OVERFLOW) {
si_code = TARGET_FPE_FLTOVF;
} else if (GET_FP_CAUSE(env->active_fpu.fcr31) & FP_UNDERFLOW) {
si_code = TARGET_FPE_FLTUND;
} else if (GET_FP_CAUSE(env->active_fpu.fcr31) & FP_INEXACT) {
si_code = TARGET_FPE_FLTRES;
}
force_sig_fault(TARGET_SIGFPE, si_code, env->active_tc.PC);
break;
case EXCP_OVERFLOW:
force_sig_fault(TARGET_SIGFPE, TARGET_FPE_INTOVF, env->active_tc.PC);
break;
/* The code below was inspired by the MIPS Linux kernel trap
* handling code in arch/mips/kernel/traps.c.
*/
case EXCP_BREAK:
/*
* As described in the original Linux kernel code, the below
* checks on 'code' are to work around an old assembly bug.
*/
code = env->error_code;
if (code >= (1 << 10)) {
code >>= 10;
}
do_tr_or_bp(env, code, false);
break;
case EXCP_TRAP:
do_tr_or_bp(env, env->error_code, true);
break;
case EXCP_ATOMIC:
cpu_exec_step_atomic(cs);
break;
default:
EXCP_DUMP(env, "qemu: unhandled CPU exception 0x%x - aborting\n", trapnr);
abort();
}
process_pending_signals(env);
}
}
void target_cpu_copy_regs(CPUArchState *env, struct target_pt_regs *regs)
{
CPUState *cpu = env_cpu(env);
TaskState *ts = cpu->opaque;
struct image_info *info = ts->info;
int i;
struct mode_req {
bool single;
bool soft;
bool fr1;
bool frdefault;
bool fre;
};
static const struct mode_req fpu_reqs[] = {
[MIPS_ABI_FP_ANY] = { true, true, true, true, true },
[MIPS_ABI_FP_DOUBLE] = { false, false, false, true, true },
[MIPS_ABI_FP_SINGLE] = { true, false, false, false, false },
[MIPS_ABI_FP_SOFT] = { false, true, false, false, false },
[MIPS_ABI_FP_OLD_64] = { false, false, false, false, false },
[MIPS_ABI_FP_XX] = { false, false, true, true, true },
[MIPS_ABI_FP_64] = { false, false, true, false, false },
[MIPS_ABI_FP_64A] = { false, false, true, false, true }
};
/*
* Mode requirements when .MIPS.abiflags is not present in the ELF.
* Not present means that everything is acceptable except FR1.
*/
static struct mode_req none_req = { true, true, false, true, true };
struct mode_req prog_req;
struct mode_req interp_req;
for(i = 0; i < 32; i++) {
env->active_tc.gpr[i] = regs->regs[i];
}
env->active_tc.PC = regs->cp0_epc & ~(target_ulong)1;
if (regs->cp0_epc & 1) {
env->hflags |= MIPS_HFLAG_M16;
}
#ifdef TARGET_ABI_MIPSO32
# define MAX_FP_ABI MIPS_ABI_FP_64A
#else
# define MAX_FP_ABI MIPS_ABI_FP_SOFT
#endif
if ((info->fp_abi > MAX_FP_ABI && info->fp_abi != MIPS_ABI_FP_UNKNOWN)
|| (info->interp_fp_abi > MAX_FP_ABI &&
info->interp_fp_abi != MIPS_ABI_FP_UNKNOWN)) {
fprintf(stderr, "qemu: Unexpected FPU mode\n");
exit(1);
}
prog_req = (info->fp_abi == MIPS_ABI_FP_UNKNOWN) ? none_req
: fpu_reqs[info->fp_abi];
interp_req = (info->interp_fp_abi == MIPS_ABI_FP_UNKNOWN) ? none_req
: fpu_reqs[info->interp_fp_abi];
prog_req.single &= interp_req.single;
prog_req.soft &= interp_req.soft;
prog_req.fr1 &= interp_req.fr1;
prog_req.frdefault &= interp_req.frdefault;
prog_req.fre &= interp_req.fre;
bool cpu_has_mips_r2_r6 = env->insn_flags & ISA_MIPS_R2 ||
env->insn_flags & ISA_MIPS_R6;
if (prog_req.fre && !prog_req.frdefault && !prog_req.fr1) {
env->CP0_Config5 |= (1 << CP0C5_FRE);
if (env->active_fpu.fcr0 & (1 << FCR0_FREP)) {
env->hflags |= MIPS_HFLAG_FRE;
}
} else if ((prog_req.fr1 && prog_req.frdefault) ||
(prog_req.single && !prog_req.frdefault)) {
if ((env->active_fpu.fcr0 & (1 << FCR0_F64)
&& cpu_has_mips_r2_r6) || prog_req.fr1) {
env->CP0_Status |= (1 << CP0St_FR);
env->hflags |= MIPS_HFLAG_F64;
}
} else if (prog_req.fr1) {
env->CP0_Status |= (1 << CP0St_FR);
env->hflags |= MIPS_HFLAG_F64;
} else if (!prog_req.fre && !prog_req.frdefault &&
!prog_req.fr1 && !prog_req.single && !prog_req.soft) {
fprintf(stderr, "qemu: Can't find a matching FPU mode\n");
exit(1);
}
if (env->insn_flags & ISA_NANOMIPS32) {
return;
}
if (((info->elf_flags & EF_MIPS_NAN2008) != 0) !=
((env->active_fpu.fcr31 & (1 << FCR31_NAN2008)) != 0)) {
if ((env->active_fpu.fcr31_rw_bitmask &
(1 << FCR31_NAN2008)) == 0) {
fprintf(stderr, "ELF binary's NaN mode not supported by CPU\n");
exit(1);
}
if ((info->elf_flags & EF_MIPS_NAN2008) != 0) {
env->active_fpu.fcr31 |= (1 << FCR31_NAN2008);
} else {
env->active_fpu.fcr31 &= ~(1 << FCR31_NAN2008);
}
restore_snan_bit_mode(env);
}
}
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