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linux-user/nios2: Map a real kuser page

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The first word of page1 is data, so the whole thing
can't be implemented with emulation of addresses.
Use init_guest_commpage for the allocation.

Hijack trap number 16 to implement cmpxchg.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20211221025012.1057923-5-richard.henderson@linaro.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
This commit is contained in:
Richard Henderson 2021-12-20 18:50:09 -08:00 • committed by Laurent Vivier
parent 66346faf32
commit f5ef0e518d
3 changed files with 76 additions and 33 deletions
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50
linux-user/nios2/cpu_loop.c
View file

@ -76,6 +76,32 @@ void cpu_loop(CPUNios2State *env)
force_sig_fault(TARGET_SIGILL, TARGET_ILL_ILLTRP,
env->regs[R_PC]);
break;
case 16: /* QEMU specific, for __kuser_cmpxchg */
{
abi_ptr g = env->regs[4];
uint32_t *h, n, o;
if (g & 0x3) {
force_sig_fault(TARGET_SIGBUS, TARGET_BUS_ADRALN, g);
break;
}
ret = page_get_flags(g);
if (!(ret & PAGE_VALID)) {
force_sig_fault(TARGET_SIGSEGV, TARGET_SEGV_MAPERR, g);
break;
}
if (!(ret & PAGE_READ) || !(ret & PAGE_WRITE)) {
force_sig_fault(TARGET_SIGSEGV, TARGET_SEGV_ACCERR, g);
break;
}
h = g2h(cs, g);
o = env->regs[5];
n = env->regs[6];
env->regs[2] = qatomic_cmpxchg(h, o, n) - o;
env->regs[R_PC] += 4;
}
break;
}
break;
@ -86,29 +112,7 @@ void cpu_loop(CPUNios2State *env)
queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
break;
case 0xaa:
switch (env->regs[R_PC]) {
/*case 0x1000:*/ /* TODO:__kuser_helper_version */
case 0x1004: /* __kuser_cmpxchg */
start_exclusive();
if (env->regs[4] & 0x3) {
goto kuser_fail;
}
ret = get_user_u32(env->regs[2], env->regs[4]);
if (ret) {
end_exclusive();
goto kuser_fail;
}
env->regs[2] -= env->regs[5];
if (env->regs[2] == 0) {
put_user_u32(env->regs[6], env->regs[4]);
}
end_exclusive();
env->regs[R_PC] = env->regs[R_RA];
break;
/*case 0x1040:*/ /* TODO:__kuser_sigtramp */
default:
;
kuser_fail:
{
info.si_signo = TARGET_SIGSEGV;
info.si_errno = 0;
/* TODO: check env->error_code */