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qemu-patch-raspberry4/linux-user/i386/cpu_loop.c
Peter Maydell b10089a14c linux-user: Don't call gdb_handlesig() before queue_signal() 
The CPU main-loop routines for linux-user generally
call gdb_handlesig() when they're about to queue a
SIGTRAP signal. This is wrong, because queue_signal()
will cause us to pend a signal, and process_pending_signals()
will then call gdb_handlesig() itself. So the effect is that
we notify gdb of the SIGTRAP, and then if gdb says "OK,
continue with signal X" we will incorrectly notify
gdb of the signal X as well. We don't do this double-notify
for anything else, only SIGTRAP.

Remove this unnecessary and incorrect code from all
the targets except for nios2 (whose main loop is
doing something different and broken, and will be handled
in a separate patch).

This bug only manifests if the user responds to the reported
SIGTRAP using "signal SIGFOO" rather than "continue"; since
the latter is the overwhelmingly common thing to do after a
breakpoint most people won't have hit this.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20181019174958.26616-2-peter.maydell@linaro.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
2018-11-12 15:48:00 +01:00

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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 "cpu_loop-common.h"
/***********************************************************/
/* CPUX86 core interface */
uint64_t cpu_get_tsc(CPUX86State *env)
{
return cpu_get_host_ticks();
}
static void write_dt(void *ptr, unsigned long addr, unsigned long limit,
int flags)
{
unsigned int e1, e2;
uint32_t *p;
e1 = (addr << 16) | (limit & 0xffff);
e2 = ((addr >> 16) & 0xff) | (addr & 0xff000000) | (limit & 0x000f0000);
e2 |= flags;
p = ptr;
p[0] = tswap32(e1);
p[1] = tswap32(e2);
}
static uint64_t *idt_table;
#ifdef TARGET_X86_64
static void set_gate64(void *ptr, unsigned int type, unsigned int dpl,
uint64_t addr, unsigned int sel)
{
uint32_t *p, e1, e2;
e1 = (addr & 0xffff) | (sel << 16);
e2 = (addr & 0xffff0000) | 0x8000 | (dpl << 13) | (type << 8);
p = ptr;
p[0] = tswap32(e1);
p[1] = tswap32(e2);
p[2] = tswap32(addr >> 32);
p[3] = 0;
}
/* only dpl matters as we do only user space emulation */
static void set_idt(int n, unsigned int dpl)
{
set_gate64(idt_table + n * 2, 0, dpl, 0, 0);
}
#else
static void set_gate(void *ptr, unsigned int type, unsigned int dpl,
uint32_t addr, unsigned int sel)
{
uint32_t *p, e1, e2;
e1 = (addr & 0xffff) | (sel << 16);
e2 = (addr & 0xffff0000) | 0x8000 | (dpl << 13) | (type << 8);
p = ptr;
p[0] = tswap32(e1);
p[1] = tswap32(e2);
}
/* only dpl matters as we do only user space emulation */
static void set_idt(int n, unsigned int dpl)
{
set_gate(idt_table + n, 0, dpl, 0, 0);
}
#endif
void cpu_loop(CPUX86State *env)
{
CPUState *cs = CPU(x86_env_get_cpu(env));
int trapnr;
abi_ulong pc;
abi_ulong ret;
target_siginfo_t info;
for(;;) {
cpu_exec_start(cs);
trapnr = cpu_exec(cs);
cpu_exec_end(cs);
process_queued_cpu_work(cs);
switch(trapnr) {
case 0x80:
/* linux syscall from int $0x80 */
ret = do_syscall(env,
env->regs[R_EAX],
env->regs[R_EBX],
env->regs[R_ECX],
env->regs[R_EDX],
env->regs[R_ESI],
env->regs[R_EDI],
env->regs[R_EBP],
0, 0);
if (ret == -TARGET_ERESTARTSYS) {
env->eip -= 2;
} else if (ret != -TARGET_QEMU_ESIGRETURN) {
env->regs[R_EAX] = ret;
}
break;
#ifndef TARGET_ABI32
case EXCP_SYSCALL:
/* linux syscall from syscall instruction */
ret = do_syscall(env,
env->regs[R_EAX],
env->regs[R_EDI],
env->regs[R_ESI],
env->regs[R_EDX],
env->regs[10],
env->regs[8],
env->regs[9],
0, 0);
if (ret == -TARGET_ERESTARTSYS) {
env->eip -= 2;
} else if (ret != -TARGET_QEMU_ESIGRETURN) {
env->regs[R_EAX] = ret;
}
break;
#endif
case EXCP0B_NOSEG:
case EXCP0C_STACK:
info.si_signo = TARGET_SIGBUS;
info.si_errno = 0;
info.si_code = TARGET_SI_KERNEL;
info._sifields._sigfault._addr = 0;
queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
break;
case EXCP0D_GPF:
/* XXX: potential problem if ABI32 */
#ifndef TARGET_X86_64
if (env->eflags & VM_MASK) {
handle_vm86_fault(env);
} else
#endif
{
info.si_signo = TARGET_SIGSEGV;
info.si_errno = 0;
info.si_code = TARGET_SI_KERNEL;
info._sifields._sigfault._addr = 0;
queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
}
break;
case EXCP0E_PAGE:
info.si_signo = TARGET_SIGSEGV;
info.si_errno = 0;
if (!(env->error_code & 1))
info.si_code = TARGET_SEGV_MAPERR;
else
info.si_code = TARGET_SEGV_ACCERR;
info._sifields._sigfault._addr = env->cr[2];
queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
break;
case EXCP00_DIVZ:
#ifndef TARGET_X86_64
if (env->eflags & VM_MASK) {
handle_vm86_trap(env, trapnr);
} else
#endif
{
/* division by zero */
info.si_signo = TARGET_SIGFPE;
info.si_errno = 0;
info.si_code = TARGET_FPE_INTDIV;
info._sifields._sigfault._addr = env->eip;
queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
}
break;
case EXCP01_DB:
case EXCP03_INT3:
#ifndef TARGET_X86_64
if (env->eflags & VM_MASK) {
handle_vm86_trap(env, trapnr);
} else
#endif
{
info.si_signo = TARGET_SIGTRAP;
info.si_errno = 0;
if (trapnr == EXCP01_DB) {
info.si_code = TARGET_TRAP_BRKPT;
info._sifields._sigfault._addr = env->eip;
} else {
info.si_code = TARGET_SI_KERNEL;
info._sifields._sigfault._addr = 0;
}
queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
}
break;
case EXCP04_INTO:
case EXCP05_BOUND:
#ifndef TARGET_X86_64
if (env->eflags & VM_MASK) {
handle_vm86_trap(env, trapnr);
} else
#endif
{
info.si_signo = TARGET_SIGSEGV;
info.si_errno = 0;
info.si_code = TARGET_SI_KERNEL;
info._sifields._sigfault._addr = 0;
queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
}
break;
case EXCP06_ILLOP:
info.si_signo = TARGET_SIGILL;
info.si_errno = 0;
info.si_code = TARGET_ILL_ILLOPN;
info._sifields._sigfault._addr = env->eip;
queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
break;
case EXCP_INTERRUPT:
/* just indicate that signals should be handled asap */
break;
case EXCP_DEBUG:
info.si_signo = TARGET_SIGTRAP;
info.si_errno = 0;
info.si_code = TARGET_TRAP_BRKPT;
queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
break;
case EXCP_ATOMIC:
cpu_exec_step_atomic(cs);
break;
default:
pc = env->segs[R_CS].base + env->eip;
EXCP_DUMP(env, "qemu: 0x%08lx: unhandled CPU exception 0x%x - aborting\n",
(long)pc, trapnr);
abort();
}
process_pending_signals(env);
}
}
void target_cpu_copy_regs(CPUArchState *env, struct target_pt_regs *regs)
{
env->cr[0] = CR0_PG_MASK | CR0_WP_MASK | CR0_PE_MASK;
env->hflags |= HF_PE_MASK | HF_CPL_MASK;
if (env->features[FEAT_1_EDX] & CPUID_SSE) {
env->cr[4] |= CR4_OSFXSR_MASK;
env->hflags |= HF_OSFXSR_MASK;
}
#ifndef TARGET_ABI32
/* enable 64 bit mode if possible */
if (!(env->features[FEAT_8000_0001_EDX] & CPUID_EXT2_LM)) {
fprintf(stderr, "The selected x86 CPU does not support 64 bit mode\n");
exit(EXIT_FAILURE);
}
env->cr[4] |= CR4_PAE_MASK;
env->efer |= MSR_EFER_LMA | MSR_EFER_LME;
env->hflags |= HF_LMA_MASK;
#endif
/* flags setup : we activate the IRQs by default as in user mode */
env->eflags |= IF_MASK;
/* linux register setup */
#ifndef TARGET_ABI32
env->regs[R_EAX] = regs->rax;
env->regs[R_EBX] = regs->rbx;
env->regs[R_ECX] = regs->rcx;
env->regs[R_EDX] = regs->rdx;
env->regs[R_ESI] = regs->rsi;
env->regs[R_EDI] = regs->rdi;
env->regs[R_EBP] = regs->rbp;
env->regs[R_ESP] = regs->rsp;
env->eip = regs->rip;
#else
env->regs[R_EAX] = regs->eax;
env->regs[R_EBX] = regs->ebx;
env->regs[R_ECX] = regs->ecx;
env->regs[R_EDX] = regs->edx;
env->regs[R_ESI] = regs->esi;
env->regs[R_EDI] = regs->edi;
env->regs[R_EBP] = regs->ebp;
env->regs[R_ESP] = regs->esp;
env->eip = regs->eip;
#endif
/* linux interrupt setup */
#ifndef TARGET_ABI32
env->idt.limit = 511;
#else
env->idt.limit = 255;
#endif
env->idt.base = target_mmap(0, sizeof(uint64_t) * (env->idt.limit + 1),
PROT_READ|PROT_WRITE,
MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
idt_table = g2h(env->idt.base);
set_idt(0, 0);
set_idt(1, 0);
set_idt(2, 0);
set_idt(3, 3);
set_idt(4, 3);
set_idt(5, 0);
set_idt(6, 0);
set_idt(7, 0);
set_idt(8, 0);
set_idt(9, 0);
set_idt(10, 0);
set_idt(11, 0);
set_idt(12, 0);
set_idt(13, 0);
set_idt(14, 0);
set_idt(15, 0);
set_idt(16, 0);
set_idt(17, 0);
set_idt(18, 0);
set_idt(19, 0);
set_idt(0x80, 3);
/* linux segment setup */
{
uint64_t *gdt_table;
env->gdt.base = target_mmap(0, sizeof(uint64_t) * TARGET_GDT_ENTRIES,
PROT_READ|PROT_WRITE,
MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
env->gdt.limit = sizeof(uint64_t) * TARGET_GDT_ENTRIES - 1;
gdt_table = g2h(env->gdt.base);
#ifdef TARGET_ABI32
write_dt(&gdt_table[__USER_CS >> 3], 0, 0xfffff,
DESC_G_MASK | DESC_B_MASK | DESC_P_MASK | DESC_S_MASK |
(3 << DESC_DPL_SHIFT) | (0xa << DESC_TYPE_SHIFT));
#else
/* 64 bit code segment */
write_dt(&gdt_table[__USER_CS >> 3], 0, 0xfffff,
DESC_G_MASK | DESC_B_MASK | DESC_P_MASK | DESC_S_MASK |
DESC_L_MASK |
(3 << DESC_DPL_SHIFT) | (0xa << DESC_TYPE_SHIFT));
#endif
write_dt(&gdt_table[__USER_DS >> 3], 0, 0xfffff,
DESC_G_MASK | DESC_B_MASK | DESC_P_MASK | DESC_S_MASK |
(3 << DESC_DPL_SHIFT) | (0x2 << DESC_TYPE_SHIFT));
}
cpu_x86_load_seg(env, R_CS, __USER_CS);
cpu_x86_load_seg(env, R_SS, __USER_DS);
#ifdef TARGET_ABI32
cpu_x86_load_seg(env, R_DS, __USER_DS);
cpu_x86_load_seg(env, R_ES, __USER_DS);
cpu_x86_load_seg(env, R_FS, __USER_DS);
cpu_x86_load_seg(env, R_GS, __USER_DS);
/* This hack makes Wine work... */
env->segs[R_FS].selector = 0;
#else
cpu_x86_load_seg(env, R_DS, 0);
cpu_x86_load_seg(env, R_ES, 0);
cpu_x86_load_seg(env, R_FS, 0);
cpu_x86_load_seg(env, R_GS, 0);
#endif
}
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