The first word of page1 is data, so the whole thing
can't be implemented with emulation of addresses.
Hijack trap number 31 to implement cmpxchg.
Set default_rt_sigreturn based on the kuser page.
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
linux-user/nios2/target_signal.h | 3 ++
linux-user/elfload.c | 35 ++++++++++++++++++++++
linux-user/nios2/cpu_loop.c | 51 +++++++++++++++++---------------
linux-user/nios2/signal.c | 2 +-
target/nios2/translate.c | 9 ------
5 files changed, 66 insertions(+), 34 deletions(-)
diff --git a/linux-user/nios2/target_signal.h b/linux-user/nios2/target_signal.h
index aebf749f12..fe266c4c51 100644
--- a/linux-user/nios2/target_signal.h
+++ b/linux-user/nios2/target_signal.h
@@ -19,4 +19,7 @@ typedef struct target_sigaltstack {
#include "../generic/signal.h"
+/* Nios2 uses a fixed address on the kuser page for sigreturn. */
+#define TARGET_ARCH_HAS_SIGTRAMP_PAGE 0
+
#endif /* NIOS2_TARGET_SIGNAL_H */
diff --git a/linux-user/elfload.c b/linux-user/elfload.c
index 459a26ef1d..7b3a91b3ed 100644
--- a/linux-user/elfload.c
+++ b/linux-user/elfload.c
@@ -1100,6 +1100,41 @@ static void elf_core_copy_regs(target_elf_gregset_t *regs, const CPUMBState *env
static void init_thread(struct target_pt_regs *regs, struct image_info *infop)
{
+ static const uint8_t kuser_page[4 + 2 * 64] = {
+ /* __kuser_helper_version */
+ [0x00] = 0x02, 0x00, 0x00, 0x00,
+
+ /* __kuser_cmpxchg */
+ [0x04] = 0xfa, 0x6f, 0x3b, 0x00, /* trap 31 */
+ 0x3a, 0x28, 0x00, 0xf8, /* ret */
+
+ /* __kuser_sigtramp */
+ [0x44] = 0xc4, 0x22, 0x80, 0x00, /* movi r2, __NR_rt_sigreturn */
+ 0x3a, 0x68, 0x3b, 0x00, /* trap 0 */
+ };
+
+ abi_ulong pg;
+ uint8_t *ph;
+
+ pg = target_mmap(TARGET_PAGE_SIZE, TARGET_PAGE_SIZE,
+ PROT_READ | PROT_WRITE,
+ MAP_ANON | MAP_PRIVATE | MAP_FIXED, -1, 0);
+
+ /*
+ * If the mmap doesn't give us exactly page 1, there's nothing
+ * we can do, and it's unlikely that the program will be able
+ * to continue. FIXME: Error out now?
+ */
+ assert(pg == TARGET_PAGE_SIZE);
+
+ ph = lock_user(VERIFY_WRITE, pg, sizeof(kuser_page), 0);
+ memcpy(ph, kuser_page, sizeof(kuser_page));
+ unlock_user(ph, pg, sizeof(kuser_page));
+ target_mprotect(TARGET_PAGE_SIZE, TARGET_PAGE_SIZE, PROT_READ | PROT_EXEC);
+
+ /* Install __kuser_sigtramp */
+ default_rt_sigreturn = TARGET_PAGE_SIZE + 0x44;
+
regs->ea = infop->entry;
regs->sp = infop->start_stack;
regs->estatus = 0x3;
diff --git a/linux-user/nios2/cpu_loop.c b/linux-user/nios2/cpu_loop.c
index 246293a501..12070c8a3c 100644
--- a/linux-user/nios2/cpu_loop.c
+++ b/linux-user/nios2/cpu_loop.c
@@ -26,7 +26,6 @@
void cpu_loop(CPUNios2State *env)
{
CPUState *cs = env_cpu(env);
- Nios2CPU *cpu = NIOS2_CPU(cs);
target_siginfo_t info;
int trapnr, ret;
@@ -73,6 +72,32 @@ void cpu_loop(CPUNios2State *env)
force_sig_fault(TARGET_SIGILL, TARGET_ILL_ILLTRP,
env->regs[R_PC]);
break;
+
+ case 31: /* 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;
@@ -83,29 +108,7 @@ 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 */
diff --git a/linux-user/nios2/signal.c b/linux-user/nios2/signal.c
index a77e8a40f4..c9a235ded5 100644
--- a/linux-user/nios2/signal.c
+++ b/linux-user/nios2/signal.c
@@ -177,7 +177,7 @@ void setup_rt_frame(int sig, struct target_sigaction *ka,
/* Set up to return from userspace; jump to fixed address sigreturn
trampoline on kuser page. */
- env->regs[R_RA] = (unsigned long) (0x1044);
+ env->regs[R_RA] = default_rt_sigreturn;
/* Set up registers for signal handler */
env->regs[R_SP] = (unsigned long) frame;
diff --git a/target/nios2/translate.c b/target/nios2/translate.c
index 485b487665..77706dd805 100644
--- a/target/nios2/translate.c
+++ b/target/nios2/translate.c
@@ -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);
--
2.25.1