target-arm queue:

* Fix the CBAR register implementation for Cortex-A53,
    Cortex-A57, Cortex-A72
  * Fix direct booting of Linux kernels on emulated CPUs
    which have an AArch32 EL3 (incorrect NSACR settings
    meant they could not access the FPU)
  * semihosting cleanup: do more work at translate time
    and less work at runtime
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Merge remote-tracking branch 'remotes/pmaydell/tags/pull-target-arm-20190927' into staging

target-arm queue:
 * Fix the CBAR register implementation for Cortex-A53,
   Cortex-A57, Cortex-A72
 * Fix direct booting of Linux kernels on emulated CPUs
   which have an AArch32 EL3 (incorrect NSACR settings
   meant they could not access the FPU)
 * semihosting cleanup: do more work at translate time
   and less work at runtime

# gpg: Signature made Fri 27 Sep 2019 15:32:43 BST
# gpg:                using RSA key E1A5C593CD419DE28E8315CF3C2525ED14360CDE
# gpg:                issuer "peter.maydell@linaro.org"
# gpg: Good signature from "Peter Maydell <peter.maydell@linaro.org>" [ultimate]
# gpg:                 aka "Peter Maydell <pmaydell@gmail.com>" [ultimate]
# gpg:                 aka "Peter Maydell <pmaydell@chiark.greenend.org.uk>" [ultimate]
# Primary key fingerprint: E1A5 C593 CD41 9DE2 8E83  15CF 3C25 25ED 1436 0CDE

* remotes/pmaydell/tags/pull-target-arm-20190927:
  hw/arm/boot: Use the IEC binary prefix definitions
  hw/arm/boot.c: Set NSACR.{CP11,CP10} for NS kernel boots
  tests/tcg: add linux-user semihosting smoke test for ARM
  target/arm: remove run-time semihosting checks for linux-user
  target/arm: remove run time semihosting checks
  target/arm: handle A-profile semihosting at translate time
  target/arm: handle M-profile semihosting at translate time
  tests/tcg: clean-up some comments after the de-tangling
  target/arm: fix CBAR register for AArch64 CPUs

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

# Conflicts:
#	tests/tcg/arm/Makefile.target

hw/arm/boot.c

@@ -575,7 +575,7 @@ int arm_load_dtb(hwaddr addr, const struct arm_boot_info *binfo,
         goto fail;
     }
 
-    if (scells < 2 && binfo->ram_size >= (1ULL << 32)) {
+    if (scells < 2 && binfo->ram_size >= 4 * GiB) {
         /* This is user error so deserves a friendlier error message
          * than the failure of setprop_sized_cells would provide
          */
@@ -754,6 +754,8 @@ static void do_cpu_reset(void *opaque)
                     (cs != first_cpu || !info->secure_board_setup)) {
                     /* Linux expects non-secure state */
                     env->cp15.scr_el3 |= SCR_NS;
+                    /* Set NSACR.{CP11,CP10} so NS can access the FPU */
+                    env->cp15.nsacr |= 3 << 10;
                 }
             }
 
@@ -1095,7 +1097,7 @@ static void arm_setup_direct_kernel_boot(ARMCPU *cpu,
      * we might still make a bad choice here.
      */
     info->initrd_start = info->loader_start +
-        MIN(info->ram_size / 2, 128 * 1024 * 1024);
+        MIN(info->ram_size / 2, 128 * MiB);
     if (image_high_addr) {
         info->initrd_start = MAX(info->initrd_start, image_high_addr);
     }
@@ -1155,13 +1157,13 @@ static void arm_setup_direct_kernel_boot(ARMCPU *cpu,
                  *
                  * Let's play safe and prealign it to 2MB to give us some space.
                  */
-                align = 2 * 1024 * 1024;
+                align = 2 * MiB;
             } else {
                 /*
                  * Some 32bit kernels will trash anything in the 4K page the
                  * initrd ends in, so make sure the DTB isn't caught up in that.
                  */
-                align = 4096;
+                align = 4 * KiB;
             }
 
             /* Place the DTB after the initrd in memory with alignment. */
@@ -1178,7 +1180,7 @@ static void arm_setup_direct_kernel_boot(ARMCPU *cpu,
                 info->loader_start + KERNEL_ARGS_ADDR;
             fixupcontext[FIXUP_ARGPTR_HI] =
                 (info->loader_start + KERNEL_ARGS_ADDR) >> 32;
-            if (info->ram_size >= (1ULL << 32)) {
+            if (info->ram_size >= 4 * GiB) {
                 error_report("RAM size must be less than 4GB to boot"
                              " Linux kernel using ATAGS (try passing a device tree"
                              " using -dtb)");

linux-user/arm/cpu_loop.c

@@ -325,9 +325,6 @@ void cpu_loop(CPUARMState *env)
 
                 if (n == ARM_NR_cacheflush) {
                     /* nop */
-                } else if (n == ARM_NR_semihosting
-                           || n == ARM_NR_thumb_semihosting) {
-                    env->regs[0] = do_arm_semihosting (env);
                 } else if (n == 0 || n >= ARM_SYSCALL_BASE || env->thumb) {
                     /* linux syscall */
                     if (env->thumb || n == 0) {

linux-user/arm/target_syscall.h

@@ -18,9 +18,6 @@ struct target_pt_regs {
 #define ARM_NR_set_tls	  (ARM_NR_BASE + 5)
 #define ARM_NR_get_tls    (ARM_NR_BASE + 6)
 
-#define ARM_NR_semihosting	  0x123456
-#define ARM_NR_thumb_semihosting  0xAB
-
 #if defined(TARGET_WORDS_BIGENDIAN)
 #define UNAME_MACHINE "armv5teb"
 #else

target/arm/helper.c

@@ -6733,6 +6733,19 @@ void register_cp_regs_for_features(ARMCPU *cpu)
     }
 
     if (arm_feature(env, ARM_FEATURE_CBAR)) {
+        /*
+         * CBAR is IMPDEF, but common on Arm Cortex-A implementations.
+         * There are two flavours:
+         *  (1) older 32-bit only cores have a simple 32-bit CBAR
+         *  (2) 64-bit cores have a 64-bit CBAR visible to AArch64, plus a
+         *      32-bit register visible to AArch32 at a different encoding
+         *      to the "flavour 1" register and with the bits rearranged to
+         *      be able to squash a 64-bit address into the 32-bit view.
+         * We distinguish the two via the ARM_FEATURE_AARCH64 flag, but
+         * in future if we support AArch32-only configs of some of the
+         * AArch64 cores we might need to add a specific feature flag
+         * to indicate cores with "flavour 2" CBAR.
+         */
         if (arm_feature(env, ARM_FEATURE_AARCH64)) {
             /* 32 bit view is [31:18] 0...0 [43:32]. */
             uint32_t cbar32 = (extract64(cpu->reset_cbar, 18, 14) << 18)
@@ -6740,12 +6753,12 @@ void register_cp_regs_for_features(ARMCPU *cpu)
             ARMCPRegInfo cbar_reginfo[] = {
                 { .name = "CBAR",
                   .type = ARM_CP_CONST,
-                  .cp = 15, .crn = 15, .crm = 0, .opc1 = 4, .opc2 = 0,
+                  .cp = 15, .crn = 15, .crm = 3, .opc1 = 1, .opc2 = 0,
-                  .access = PL1_R, .resetvalue = cpu->reset_cbar },
+                  .access = PL1_R, .resetvalue = cbar32 },
                 { .name = "CBAR_EL1", .state = ARM_CP_STATE_AA64,
                   .type = ARM_CP_CONST,
                   .opc0 = 3, .opc1 = 1, .crn = 15, .crm = 3, .opc2 = 0,
-                  .access = PL1_R, .resetvalue = cbar32 },
+                  .access = PL1_R, .resetvalue = cpu->reset_cbar },
                 REGINFO_SENTINEL
             };
             /* We don't implement a r/w 64 bit CBAR currently */
@@ -8339,88 +8352,32 @@ static void arm_cpu_do_interrupt_aarch64(CPUState *cs)
                   new_el, env->pc, pstate_read(env));
 }
 
-static inline bool check_for_semihosting(CPUState *cs)
+/*
-{
+ * Do semihosting call and set the appropriate return value. All the
+ * permission and validity checks have been done at translate time.
+ *
+ * We only see semihosting exceptions in TCG only as they are not
+ * trapped to the hypervisor in KVM.
+ */
 #ifdef CONFIG_TCG
-    /* Check whether this exception is a semihosting call; if so
+static void handle_semihosting(CPUState *cs)
-     * then handle it and return true; otherwise return false.
+{
-     */
     ARMCPU *cpu = ARM_CPU(cs);
     CPUARMState *env = &cpu->env;
 
     if (is_a64(env)) {
-        if (cs->exception_index == EXCP_SEMIHOST) {
+        qemu_log_mask(CPU_LOG_INT,
-            /* This is always the 64-bit semihosting exception.
+                      "...handling as semihosting call 0x%" PRIx64 "\n",
-             * The "is this usermode" and "is semihosting enabled"
+                      env->xregs[0]);
-             * checks have been done at translate time.
+        env->xregs[0] = do_arm_semihosting(env);
-             */
-            qemu_log_mask(CPU_LOG_INT,
-                          "...handling as semihosting call 0x%" PRIx64 "\n",
-                          env->xregs[0]);
-            env->xregs[0] = do_arm_semihosting(env);
-            return true;
-        }
-        return false;
     } else {
-        uint32_t imm;
-
-        /* Only intercept calls from privileged modes, to provide some
-         * semblance of security.
-         */
-        if (cs->exception_index != EXCP_SEMIHOST &&
-            (!semihosting_enabled() ||
-             ((env->uncached_cpsr & CPSR_M) == ARM_CPU_MODE_USR))) {
-            return false;
-        }
-
-        switch (cs->exception_index) {
-        case EXCP_SEMIHOST:
-            /* This is always a semihosting call; the "is this usermode"
-             * and "is semihosting enabled" checks have been done at
-             * translate time.
-             */
-            break;
-        case EXCP_SWI:
-            /* Check for semihosting interrupt.  */
-            if (env->thumb) {
-                imm = arm_lduw_code(env, env->regs[15] - 2, arm_sctlr_b(env))
-                    & 0xff;
-                if (imm == 0xab) {
-                    break;
-                }
-            } else {
-                imm = arm_ldl_code(env, env->regs[15] - 4, arm_sctlr_b(env))
-                    & 0xffffff;
-                if (imm == 0x123456) {
-                    break;
-                }
-            }
-            return false;
-        case EXCP_BKPT:
-            /* See if this is a semihosting syscall.  */
-            if (env->thumb) {
-                imm = arm_lduw_code(env, env->regs[15], arm_sctlr_b(env))
-                    & 0xff;
-                if (imm == 0xab) {
-                    env->regs[15] += 2;
-                    break;
-                }
-            }
-            return false;
-        default:
-            return false;
-        }
-
         qemu_log_mask(CPU_LOG_INT,
                       "...handling as semihosting call 0x%x\n",
                       env->regs[0]);
         env->regs[0] = do_arm_semihosting(env);
-        return true;
     }
-#else
-    return false;
-#endif
 }
+#endif
 
 /* Handle a CPU exception for A and R profile CPUs.
  * Do any appropriate logging, handle PSCI calls, and then hand off
@@ -8451,13 +8408,17 @@ void arm_cpu_do_interrupt(CPUState *cs)
         return;
     }
 
-    /* Semihosting semantics depend on the register width of the
+    /*
-     * code that caused the exception, not the target exception level,
+     * Semihosting semantics depend on the register width of the code
-     * so must be handled here.
+     * that caused the exception, not the target exception level, so
+     * must be handled here.
      */
-    if (check_for_semihosting(cs)) {
+#ifdef CONFIG_TCG
+    if (cs->exception_index == EXCP_SEMIHOST) {
+        handle_semihosting(cs);
         return;
     }
+#endif
 
     /* Hooks may change global state so BQL should be held, also the
      * BQL needs to be held for any modification of

target/arm/m_helper.c

@@ -2114,19 +2114,13 @@ void arm_v7m_cpu_do_interrupt(CPUState *cs)
             break;
         }
         break;
+    case EXCP_SEMIHOST:
+        qemu_log_mask(CPU_LOG_INT,
+                      "...handling as semihosting call 0x%x\n",
+                      env->regs[0]);
+        env->regs[0] = do_arm_semihosting(env);
+        return;
     case EXCP_BKPT:
-        if (semihosting_enabled()) {
-            int nr;
-            nr = arm_lduw_code(env, env->regs[15], arm_sctlr_b(env)) & 0xff;
-            if (nr == 0xab) {
-                env->regs[15] += 2;
-                qemu_log_mask(CPU_LOG_INT,
-                              "...handling as semihosting call 0x%x\n",
-                              env->regs[0]);
-                env->regs[0] = do_arm_semihosting(env);
-                return;
-            }
-        }
         armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_DEBUG, false);
         break;
     case EXCP_IRQ:

target/arm/translate.c

@@ -8424,7 +8424,16 @@ static bool trans_BKPT(DisasContext *s, arg_BKPT *a)
     if (!ENABLE_ARCH_5) {
         return false;
     }
-    gen_exception_bkpt_insn(s, syn_aa32_bkpt(a->imm, false));
+    if (arm_dc_feature(s, ARM_FEATURE_M) &&
+        semihosting_enabled() &&
+#ifndef CONFIG_USER_ONLY
+        !IS_USER(s) &&
+#endif
+        (a->imm == 0xab)) {
+        gen_exception_internal_insn(s, s->base.pc_next, EXCP_SEMIHOST);
+    } else {
+        gen_exception_bkpt_insn(s, syn_aa32_bkpt(a->imm, false));
+    }
     return true;
 }
 
@@ -10213,14 +10222,25 @@ static bool trans_CBZ(DisasContext *s, arg_CBZ *a)
 }
 
 /*
- * Supervisor call
+ * Supervisor call - both T32 & A32 come here so we need to check
+ * which mode we are in when checking for semihosting.
  */
 
 static bool trans_SVC(DisasContext *s, arg_SVC *a)
 {
-    gen_set_pc_im(s, s->base.pc_next);
+    const uint32_t semihost_imm = s->thumb ? 0xab : 0x123456;
-    s->svc_imm = a->imm;
+
-    s->base.is_jmp = DISAS_SWI;
+    if (!arm_dc_feature(s, ARM_FEATURE_M) && semihosting_enabled() &&
+#ifndef CONFIG_USER_ONLY
+        !IS_USER(s) &&
+#endif
+        (a->imm == semihost_imm)) {
+        gen_exception_internal_insn(s, s->base.pc_next, EXCP_SEMIHOST);
+    } else {
+        gen_set_pc_im(s, s->base.pc_next);
+        s->svc_imm = a->imm;
+        s->base.is_jmp = DISAS_SWI;
+    }
     return true;
 }
 

tests/tcg/aarch64/Makefile.target

@@ -21,4 +21,9 @@ run-fcvt: fcvt
 AARCH64_TESTS += pauth-1 pauth-2
 run-pauth-%: QEMU_OPTS += -cpu max
 
+# Semihosting smoke test for linux-user
+AARCH64_TESTS += semihosting
+run-semihosting: semihosting
+	$(call run-test,$<,$(QEMU) $< 2> $<.err, "$< on $(TARGET_NAME)")
+
 TESTS += $(AARCH64_TESTS)

tests/tcg/arm/Makefile.target

@@ -8,7 +8,6 @@ ARM_SRC=$(SRC_PATH)/tests/tcg/arm
 # Set search path for all sources
 VPATH 		+= $(ARM_SRC)
 
-# Multiarch Tests
 float_madds: CFLAGS+=-mfpu=neon-vfpv4
 
 # Basic Hello World
@@ -30,6 +29,11 @@ run-fcvt: fcvt
 	$(call run-test,fcvt,$(QEMU) $<,"$< on $(TARGET_NAME)")
 	$(call diff-out,fcvt,$(ARM_SRC)/fcvt.ref)
 
+# Semihosting smoke test for linux-user
+ARM_TESTS += semihosting
+run-semihosting: semihosting
+	$(call run-test,$<,$(QEMU) $< 2> $<.err, "$< on $(TARGET_NAME)")
+
 TESTS += $(ARM_TESTS)
 
 # On ARM Linux only supports 4k pages

tests/tcg/arm/semihosting.c

@@ -0,0 +1,45 @@
+/*
+ * linux-user semihosting checks
+ *
+ * Copyright (c) 2019
+ * Written by Alex Bennée <alex.bennee@linaro.org>
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include <stdint.h>
+
+#define SYS_WRITE0      0x04
+#define SYS_REPORTEXC   0x18
+
+void __semi_call(uintptr_t type, uintptr_t arg0)
+{
+#if defined(__arm__)
+    register uintptr_t t asm("r0") = type;
+    register uintptr_t a0 asm("r1") = arg0;
+    asm("svc 0xab"
+        : /* no return */
+        : "r" (t), "r" (a0));
+#else
+    register uintptr_t t asm("x0") = type;
+    register uintptr_t a0 asm("x1") = arg0;
+    asm("hlt 0xf000"
+        : /* no return */
+        : "r" (t), "r" (a0));
+#endif
+}
+
+int main(int argc, char *argv[argc])
+{
+#if defined(__arm__)
+    uintptr_t exit_code = 0x20026;
+#else
+    uintptr_t exit_block[2] = {0x20026, 0};
+    uintptr_t exit_code = (uintptr_t) &exit_block;
+#endif
+
+    __semi_call(SYS_WRITE0, (uintptr_t) "Hello World");
+    __semi_call(SYS_REPORTEXC, exit_code);
+    /* if we get here we failed */
+    return -1;
+}