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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 "elf.h"
#include "cpu_loop-common.h"
#include "signal-common.h"
#include "semihosting/common-semi.h"
#include "exec/page-protection.h"
#include "target/arm/syndrome.h"
#define get_user_code_u32(x, gaddr, env) \
({ abi_long __r = get_user_u32((x), (gaddr)); \
if (!__r && bswap_code(arm_sctlr_b(env))) { \
(x) = bswap32(x); \
} \
__r; \
})
#define get_user_code_u16(x, gaddr, env) \
({ abi_long __r = get_user_u16((x), (gaddr)); \
if (!__r && bswap_code(arm_sctlr_b(env))) { \
(x) = bswap16(x); \
} \
__r; \
})
#define get_user_data_u32(x, gaddr, env) \
({ abi_long __r = get_user_u32((x), (gaddr)); \
if (!__r && arm_cpu_bswap_data(env)) { \
(x) = bswap32(x); \
} \
__r; \
})
#define get_user_data_u16(x, gaddr, env) \
({ abi_long __r = get_user_u16((x), (gaddr)); \
if (!__r && arm_cpu_bswap_data(env)) { \
(x) = bswap16(x); \
} \
__r; \
})
#define put_user_data_u32(x, gaddr, env) \
({ typeof(x) __x = (x); \
if (arm_cpu_bswap_data(env)) { \
__x = bswap32(__x); \
} \
put_user_u32(__x, (gaddr)); \
})
#define put_user_data_u16(x, gaddr, env) \
({ typeof(x) __x = (x); \
if (arm_cpu_bswap_data(env)) { \
__x = bswap16(__x); \
} \
put_user_u16(__x, (gaddr)); \
})
/*
* Similar to code in accel/tcg/user-exec.c, but outside the execution loop.
* Must be called with mmap_lock.
* We get the PC of the entry address - which is as good as anything,
* on a real kernel what you get depends on which mode it uses.
*/
static void *atomic_mmu_lookup(CPUArchState *env, uint32_t addr, int size)
{
int need_flags = PAGE_READ | PAGE_WRITE_ORG | PAGE_VALID;
int page_flags;
/* Enforce guest required alignment. */
if (unlikely(addr & (size - 1))) {
force_sig_fault(TARGET_SIGBUS, TARGET_BUS_ADRALN, addr);
return NULL;
}
page_flags = page_get_flags(addr);
if (unlikely((page_flags & need_flags) != need_flags)) {
force_sig_fault(TARGET_SIGSEGV,
page_flags & PAGE_VALID ?
TARGET_SEGV_ACCERR : TARGET_SEGV_MAPERR, addr);
return NULL;
}
return g2h(env_cpu(env), addr);
}
/*
* See the Linux kernel's Documentation/arm/kernel_user_helpers.rst
* Input:
* r0 = oldval
* r1 = newval
* r2 = pointer to target value
*
* Output:
* r0 = 0 if *ptr was changed, non-0 if no exchange happened
* C set if *ptr was changed, clear if no exchange happened
*/
static void arm_kernel_cmpxchg32_helper(CPUARMState *env)
{
uint32_t oldval, newval, val, addr, cpsr, *host_addr;
/* Swap if host != guest endianness, for the host cmpxchg below */
oldval = tswap32(env->regs[0]);
newval = tswap32(env->regs[1]);
addr = env->regs[2];
mmap_lock();
host_addr = atomic_mmu_lookup(env, addr, 4);
if (!host_addr) {
mmap_unlock();
return;
}
val = qatomic_cmpxchg__nocheck(host_addr, oldval, newval);
mmap_unlock();
cpsr = (val == oldval) * CPSR_C;
cpsr_write(env, cpsr, CPSR_C, CPSRWriteByInstr);
env->regs[0] = cpsr ? 0 : -1;
}
/*
* See the Linux kernel's Documentation/arm/kernel_user_helpers.rst
* Input:
* r0 = pointer to oldval
* r1 = pointer to newval
* r2 = pointer to target value
*
* Output:
* r0 = 0 if *ptr was changed, non-0 if no exchange happened
* C set if *ptr was changed, clear if no exchange happened
*
* Note segv's in kernel helpers are a bit tricky, we can set the
* data address sensibly but the PC address is just the entry point.
*/
static void arm_kernel_cmpxchg64_helper(CPUARMState *env)
{
uint64_t oldval, newval, val;
uint32_t addr, cpsr;
uint64_t *host_addr;
addr = env->regs[0];
if (get_user_u64(oldval, addr)) {
goto segv;
}
addr = env->regs[1];
if (get_user_u64(newval, addr)) {
goto segv;
}
mmap_lock();
addr = env->regs[2];
host_addr = atomic_mmu_lookup(env, addr, 8);
if (!host_addr) {
mmap_unlock();
return;
}
/* Swap if host != guest endianness, for the host cmpxchg below */
oldval = tswap64(oldval);
newval = tswap64(newval);
#ifdef CONFIG_ATOMIC64
val = qatomic_cmpxchg__nocheck(host_addr, oldval, newval);
cpsr = (val == oldval) * CPSR_C;
#else
/*
* This only works between threads, not between processes, but since
* the host has no 64-bit cmpxchg, it is the best that we can do.
*/
start_exclusive();
val = *host_addr;
if (val == oldval) {
*host_addr = newval;
cpsr = CPSR_C;
} else {
cpsr = 0;
}
end_exclusive();
#endif
mmap_unlock();
cpsr_write(env, cpsr, CPSR_C, CPSRWriteByInstr);
env->regs[0] = cpsr ? 0 : -1;
return;
segv:
force_sig_fault(TARGET_SIGSEGV,
page_get_flags(addr) & PAGE_VALID ?
TARGET_SEGV_ACCERR : TARGET_SEGV_MAPERR, addr);
}
/* Handle a jump to the kernel code page. */
static int
do_kernel_trap(CPUARMState *env)
{
uint32_t addr;
switch (env->regs[15]) {
case 0xffff0fa0: /* __kernel_memory_barrier */
smp_mb();
break;
case 0xffff0fc0: /* __kernel_cmpxchg */
arm_kernel_cmpxchg32_helper(env);
break;
case 0xffff0fe0: /* __kernel_get_tls */
env->regs[0] = cpu_get_tls(env);
break;
case 0xffff0f60: /* __kernel_cmpxchg64 */
arm_kernel_cmpxchg64_helper(env);
break;
default:
return 1;
}
/* Jump back to the caller. */
addr = env->regs[14];
if (addr & 1) {
env->thumb = true;
addr &= ~1;
}
env->regs[15] = addr;
return 0;
}
static bool insn_is_linux_bkpt(uint32_t opcode, bool is_thumb)
{
/*
* Return true if this insn is one of the three magic UDF insns
* which the kernel treats as breakpoint insns.
*/
if (!is_thumb) {
return (opcode & 0x0fffffff) == 0x07f001f0;
} else {
/*
* Note that we get the two halves of the 32-bit T32 insn
* in the opposite order to the value the kernel uses in
* its undef_hook struct.
*/
return ((opcode & 0xffff) == 0xde01) || (opcode == 0xa000f7f0);
}
}
static bool emulate_arm_fpa11(CPUARMState *env, uint32_t opcode)
{
TaskState *ts = get_task_state(env_cpu(env));
int rc = EmulateAll(opcode, &ts->fpa, env);
int raise, enabled;
if (rc == 0) {
/* Illegal instruction */
return false;
}
if (rc > 0) {
/* Everything ok. */
env->regs[15] += 4;
return true;
}
/* FP exception */
rc = -rc;
raise = 0;
/* Translate softfloat flags to FPSR flags */
if (rc & float_flag_invalid) {
raise |= BIT_IOC;
}
if (rc & float_flag_divbyzero) {
raise |= BIT_DZC;
}
if (rc & float_flag_overflow) {
raise |= BIT_OFC;
}
if (rc & float_flag_underflow) {
raise |= BIT_UFC;
}
if (rc & float_flag_inexact) {
raise |= BIT_IXC;
}
/* Accumulate unenabled exceptions */
enabled = ts->fpa.fpsr >> 16;
ts->fpa.fpsr |= raise & ~enabled;
if (raise & enabled) {
/*
* The kernel's nwfpe emulator does not pass a real si_code.
* It merely uses send_sig(SIGFPE, current, 1), which results in
* __send_signal() filling out SI_KERNEL with pid and uid 0 (under
* the "SEND_SIG_PRIV" case). That's what our force_sig() does.
*/
force_sig(TARGET_SIGFPE);
} else {
env->regs[15] += 4;
}
return true;
}
void cpu_loop(CPUARMState *env)
{
CPUState *cs = env_cpu(env);
int trapnr, si_signo, si_code;
unsigned int n, insn;
abi_ulong ret;
for(;;) {
cpu_exec_start(cs);
trapnr = cpu_exec(cs);
cpu_exec_end(cs);
process_queued_cpu_work(cs);
switch(trapnr) {
case EXCP_UDEF:
case EXCP_NOCP:
case EXCP_INVSTATE:
{
uint32_t opcode;
/* we handle the FPU emulation here, as Linux */
/* we get the opcode */
/* FIXME - what to do if get_user() fails? */
get_user_code_u32(opcode, env->regs[15], env);
/*
* The Linux kernel treats some UDF patterns specially
* to use as breakpoints (instead of the architectural
* bkpt insn). These should trigger a SIGTRAP rather
* than SIGILL.
*/
if (insn_is_linux_bkpt(opcode, env->thumb)) {
goto excp_debug;
}
if (!env->thumb && emulate_arm_fpa11(env, opcode)) {
break;
}
force_sig_fault(TARGET_SIGILL, TARGET_ILL_ILLOPN,
env->regs[15]);
}
break;
case EXCP_SWI:
{
env->eabi = true;
/* system call */
if (env->thumb) {
/* Thumb is always EABI style with syscall number in r7 */
n = env->regs[7];
} else {
/*
* Equivalent of kernel CONFIG_OABI_COMPAT: read the
* Arm SVC insn to extract the immediate, which is the
* syscall number in OABI.
*/
/* FIXME - what to do if get_user() fails? */
get_user_code_u32(insn, env->regs[15] - 4, env);
n = insn & 0xffffff;
if (n == 0) {
/* zero immediate: EABI, syscall number in r7 */
n = env->regs[7];
} else {
/*
* This XOR matches the kernel code: an immediate
* in the valid range (0x900000 .. 0x9fffff) is
* converted into the correct EABI-style syscall
* number; invalid immediates end up as values
* > 0xfffff and are handled below as out-of-range.
*/
n ^= ARM_SYSCALL_BASE;
env->eabi = false;
}
}
if (n > ARM_NR_BASE) {
switch (n) {
case ARM_NR_cacheflush:
/* nop */
break;
case ARM_NR_set_tls:
cpu_set_tls(env, env->regs[0]);
env->regs[0] = 0;
break;
case ARM_NR_breakpoint:
env->regs[15] -= env->thumb ? 2 : 4;
goto excp_debug;
case ARM_NR_get_tls:
env->regs[0] = cpu_get_tls(env);
break;
default:
if (n < 0xf0800) {
/*
* Syscalls 0xf0000..0xf07ff (or 0x9f0000..
* 0x9f07ff in OABI numbering) are defined
* to return -ENOSYS rather than raising
* SIGILL. Note that we have already
* removed the 0x900000 prefix.
*/
qemu_log_mask(LOG_UNIMP,
"qemu: Unsupported ARM syscall: 0x%x\n",
n);
env->regs[0] = -TARGET_ENOSYS;
} else {
/*
* Otherwise SIGILL. This includes any SWI with
* immediate not originally 0x9fxxxx, because
* of the earlier XOR.
* Like the real kernel, we report the addr of the
* SWI in the siginfo si_addr but leave the PC
* pointing at the insn after the SWI.
*/
abi_ulong faultaddr = env->regs[15];
faultaddr -= env->thumb ? 2 : 4;
force_sig_fault(TARGET_SIGILL, TARGET_ILL_ILLTRP,
faultaddr);
}
break;
}
} else {
ret = do_syscall(env,
n,
env->regs[0],
env->regs[1],
env->regs[2],
env->regs[3],
env->regs[4],
env->regs[5],
0, 0);
if (ret == -QEMU_ERESTARTSYS) {
env->regs[15] -= env->thumb ? 2 : 4;
} else if (ret != -QEMU_ESIGRETURN) {
env->regs[0] = ret;
}
}
}
break;
case EXCP_SEMIHOST:
do_common_semihosting(cs);
env->regs[15] += env->thumb ? 2 : 4;
break;
case EXCP_INTERRUPT:
/* just indicate that signals should be handled asap */
break;
case EXCP_PREFETCH_ABORT:
case EXCP_DATA_ABORT:
/* For user-only we don't set TTBCR_EAE, so look at the FSR. */
switch (env->exception.fsr & 0x1f) {
case 0x1: /* Alignment */
si_signo = TARGET_SIGBUS;
si_code = TARGET_BUS_ADRALN;
break;
case 0x3: /* Access flag fault, level 1 */
case 0x6: /* Access flag fault, level 2 */
case 0x9: /* Domain fault, level 1 */
case 0xb: /* Domain fault, level 2 */
case 0xd: /* Permission fault, level 1 */
case 0xf: /* Permission fault, level 2 */
si_signo = TARGET_SIGSEGV;
si_code = TARGET_SEGV_ACCERR;
break;
case 0x5: /* Translation fault, level 1 */
case 0x7: /* Translation fault, level 2 */
si_signo = TARGET_SIGSEGV;
si_code = TARGET_SEGV_MAPERR;
break;
default:
g_assert_not_reached();
}
force_sig_fault(si_signo, si_code, env->exception.vaddress);
break;
case EXCP_DEBUG:
case EXCP_BKPT:
excp_debug:
force_sig_fault(TARGET_SIGTRAP, TARGET_TRAP_BRKPT, env->regs[15]);
break;
case EXCP_KERNEL_TRAP:
if (do_kernel_trap(env))
goto error;
break;
case EXCP_YIELD:
/* nothing to do here for user-mode, just resume guest code */
break;
case EXCP_ATOMIC:
cpu_exec_step_atomic(cs);
break;
default:
error:
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 = get_task_state(cpu);
struct image_info *info = ts->info;
int i;
cpsr_write(env, regs->uregs[16], CPSR_USER | CPSR_EXEC,
CPSRWriteByInstr);
for(i = 0; i < 16; i++) {
env->regs[i] = regs->uregs[i];
}
#if TARGET_BIG_ENDIAN
/* Enable BE8. */
if (EF_ARM_EABI_VERSION(info->elf_flags) >= EF_ARM_EABI_VER4
&& (info->elf_flags & EF_ARM_BE8)) {
env->uncached_cpsr |= CPSR_E;
env->cp15.sctlr_el[1] |= SCTLR_E0E;
} else {
env->cp15.sctlr_el[1] |= SCTLR_B;
}
arm_rebuild_hflags(env);
#endif
ts->stack_base = info->start_stack;
ts->heap_base = info->brk;
/* This will be filled in on the first SYS_HEAPINFO call. */
ts->heap_limit = 0;
}
|