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linux-user/nios2: Map a real kuser page 

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/elfload.c
View File

@ -1099,6 +1099,47 @@ static void init_thread(struct target_pt_regs *regs, struct image_info *infop)
regs->estatus = 0x3;
}
#define LO_COMMPAGE TARGET_PAGE_SIZE
static bool init_guest_commpage(void)
{
static const uint8_t kuser_page[4 + 2 * 64] = {
/* __kuser_helper_version */
[0x00] = 0x02, 0x00, 0x00, 0x00,
/* __kuser_cmpxchg */
[0x04] = 0x3a, 0x6c, 0x3b, 0x00, /* trap 16 */
0x3a, 0x28, 0x00, 0xf8, /* ret */
/* __kuser_sigtramp */
[0x44] = 0xc4, 0x22, 0x80, 0x00, /* movi r2, __NR_rt_sigreturn */
0x3a, 0x68, 0x3b, 0x00, /* trap 0 */
};
void *want = g2h_untagged(LO_COMMPAGE & -qemu_host_page_size);
void *addr = mmap(want, qemu_host_page_size, PROT_READ | PROT_WRITE,
MAP_ANONYMOUS | MAP_PRIVATE | MAP_FIXED, -1, 0);
if (addr == MAP_FAILED) {
perror("Allocating guest commpage");
exit(EXIT_FAILURE);
}
if (addr != want) {
return false;
}
memcpy(addr, kuser_page, sizeof(kuser_page));
if (mprotect(addr, qemu_host_page_size, PROT_READ)) {
perror("Protecting guest commpage");
exit(EXIT_FAILURE);
}
page_set_flags(LO_COMMPAGE, LO_COMMPAGE + TARGET_PAGE_SIZE,
PAGE_READ | PAGE_EXEC | PAGE_VALID);
return true;
}
#define ELF_EXEC_PAGESIZE 4096
#define USE_ELF_CORE_DUMP
@ -2160,8 +2201,13 @@ static abi_ulong create_elf_tables(abi_ulong p, int argc, int envc,
return sp;
}
#ifndef HI_COMMPAGE
#if defined(HI_COMMPAGE)
#define LO_COMMPAGE 0
#elif defined(LO_COMMPAGE)
#define HI_COMMPAGE 0
#else
#define HI_COMMPAGE 0
#define LO_COMMPAGE 0
#define init_guest_commpage() true
#endif
@ -2374,6 +2420,8 @@ static void pgb_static(const char *image_name, abi_ulong orig_loaddr,
} else {
offset = -(HI_COMMPAGE & -align);
}
} else if (LO_COMMPAGE) {
loaddr = MIN(loaddr, LO_COMMPAGE & -align);
}
addr = pgb_find_hole(loaddr, hiaddr - loaddr, align, offset);

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 */

9
target/nios2/translate.c
View File

@ -795,15 +795,6 @@ static void nios2_tr_translate_insn(DisasContextBase *dcbase, CPUState *cs)
dc->base.pc_next = pc + 4;
/* Decode an instruction */
#if defined(CONFIG_USER_ONLY)
/* FIXME: Is this needed ? */
if (pc >= 0x1000 && pc < 0x2000) {
t_gen_helper_raise_exception(dc, 0xaa);
return;
}
#endif
code = cpu_ldl_code(env, pc);
op = get_opcode(code);