Merge tag 'hppa-btlb-pull-request' of https://github.com/hdeller/qemu-hppa into staging

Block-TLB support and linux-user fixes for hppa target

All 32-bit hppa CPUs allow a fixed number of TLB entries to have a
different page size than the default 4k.
Those are called "Block-TLBs" and are created at startup by the
operating system and managed by the firmware of hppa machines
through the firmware PDC_BLOCK_TLB call.

This patchset adds the necessary glue to SeaBIOS-hppa and
qemu to allow up to 16 BTLB entries in the emulation.

Two patches from Mikulas Patocka fix signal delivery issues
in linux-user on hppa.

# -----BEGIN PGP SIGNATURE-----
#
# iHUEABYKAB0WIQS86RI+GtKfB8BJu973ErUQojoPXwUCZQnz0wAKCRD3ErUQojoP
# X6NDAP9F1Huhceot8peohGodRDOhnXWfDcjQZSDvadieKv/rJQEA60Z5QV5VlQgw
# SyUT4AcoiB7N4nvS+iDa+6dKfRH/YQM=
# =kqqt
# -----END PGP SIGNATURE-----
# gpg: Signature made Tue 19 Sep 2023 15:17:39 EDT
# gpg:                using EDDSA key BCE9123E1AD29F07C049BBDEF712B510A23A0F5F
# gpg: Good signature from "Helge Deller <deller@gmx.de>" [unknown]
# gpg:                 aka "Helge Deller <deller@kernel.org>" [unknown]
# gpg: WARNING: This key is not certified with a trusted signature!
# gpg:          There is no indication that the signature belongs to the owner.
# Primary key fingerprint: 4544 8228 2CD9 10DB EF3D  25F8 3E5F 3D04 A7A2 4603
#      Subkey fingerprint: BCE9 123E 1AD2 9F07 C049  BBDE F712 B510 A23A 0F5F

* tag 'hppa-btlb-pull-request' of https://github.com/hdeller/qemu-hppa:
  linux-user/hppa: lock both words of function descriptor
  linux-user/hppa: clear the PSW 'N' bit when delivering signals
  target/hppa: Wire up diag instruction to support BTLB
  target/hppa: Extract diagnose immediate value
  target/hppa: Add BTLB support to hppa TLB functions
  target/hppa: Report and clear BTLBs via fw_cfg at startup
  target/hppa: Allow up to 16 BTLB entries
  target/hppa: Update to SeaBIOS-hppa version 9

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

11 files changed, 187 insertions, 42 deletions

diff --git a/hw/hppa/machine.c b/hw/hppa/machine.c
index 866e11d208..cf28cb9586 100644
--- a/hw/hppa/machine.c
+++ b/hw/hppa/machine.c
@@ -133,14 +133,10 @@ static FWCfgState *create_fw_cfg(MachineState *ms)
     fw_cfg_add_file(fw_cfg, "/etc/firmware-min-version",
                     g_memdup(&val, sizeof(val)), sizeof(val));
 
-    val = cpu_to_le64(HPPA_TLB_ENTRIES);
+    val = cpu_to_le64(HPPA_TLB_ENTRIES - HPPA_BTLB_ENTRIES);
     fw_cfg_add_file(fw_cfg, "/etc/cpu/tlb_entries",
                     g_memdup(&val, sizeof(val)), sizeof(val));
 
-    val = cpu_to_le64(HPPA_BTLB_ENTRIES);
-    fw_cfg_add_file(fw_cfg, "/etc/cpu/btlb_entries",
-                    g_memdup(&val, sizeof(val)), sizeof(val));
-
     val = cpu_to_le64(HPA_POWER_BUTTON);
     fw_cfg_add_file(fw_cfg, "/etc/power-button-addr",
                     g_memdup(&val, sizeof(val)), sizeof(val));
@@ -433,6 +429,10 @@ static void hppa_machine_reset(MachineState *ms, ShutdownCause reason)
 
         cs->exception_index = -1;
         cs->halted = 0;
+
+        /* clear any existing TLB and BTLB entries */
+        memset(cpu[i]->env.tlb, 0, sizeof(cpu[i]->env.tlb));
+        cpu[i]->env.tlb_last = HPPA_BTLB_ENTRIES;
     }
 
     /* already initialized by machine_hppa_init()? */
diff --git a/linux-user/hppa/signal.c b/linux-user/hppa/signal.c
index f253a15864..bda6e54655 100644
--- a/linux-user/hppa/signal.c
+++ b/linux-user/hppa/signal.c
@@ -149,16 +149,18 @@ void setup_rt_frame(int sig, struct target_sigaction *ka,
         target_ulong *fdesc, dest;
 
         haddr &= -4;
-        if (!lock_user_struct(VERIFY_READ, fdesc, haddr, 1)) {
+        fdesc = lock_user(VERIFY_READ, haddr, 2 * sizeof(target_ulong), 1);
+        if (!fdesc) {
             goto give_sigsegv;
         }
         __get_user(dest, fdesc);
         __get_user(env->gr[19], fdesc + 1);
-        unlock_user_struct(fdesc, haddr, 1);
+        unlock_user(fdesc, haddr, 0);
         haddr = dest;
     }
     env->iaoq_f = haddr;
     env->iaoq_b = haddr + 4;
+    env->psw_n = 0;
     return;
 
  give_sigsegv:
diff --git a/pc-bios/hppa-firmware.img b/pc-bios/hppa-firmware.img
index 0fa3808f16..c7196143b1 100644
--- a/pc-bios/hppa-firmware.img
+++ b/pc-bios/hppa-firmware.img
diff --git a/roms/seabios-hppa b/roms/seabios-hppa
-Subproject 673d2595d4f773cc266cbf8dbaf2f475a6adb94
+Subproject 763e3b73499db5fef94087bd310bfc8ccbcf785
diff --git a/target/hppa/cpu.h b/target/hppa/cpu.h
index fa13694dab..730f35231a 100644
--- a/target/hppa/cpu.h
+++ b/target/hppa/cpu.h
@@ -211,8 +211,14 @@ typedef struct CPUArchState {
     target_ureg shadow[7];   /* shadow registers */
 
     /* ??? The number of entries isn't specified by the architecture.  */
+#ifdef TARGET_HPPA64
+#define HPPA_BTLB_FIXED         0       /* BTLBs are not supported in 64-bit machines */
+#else
+#define HPPA_BTLB_FIXED         16
+#endif
+#define HPPA_BTLB_VARIABLE      0
 #define HPPA_TLB_ENTRIES        256
-#define HPPA_BTLB_ENTRIES       0
+#define HPPA_BTLB_ENTRIES       (HPPA_BTLB_FIXED + HPPA_BTLB_VARIABLE)
 
     /* ??? Implement a unified itlb/dtlb for the moment.  */
     /* ??? We should use a more intelligent data structure.  */
@@ -344,7 +350,8 @@ bool hppa_cpu_tlb_fill(CPUState *cs, vaddr address, int size,
 void hppa_cpu_do_interrupt(CPUState *cpu);
 bool hppa_cpu_exec_interrupt(CPUState *cpu, int int_req);
 int hppa_get_physical_address(CPUHPPAState *env, vaddr addr, int mmu_idx,
-                              int type, hwaddr *pphys, int *pprot);
+                              int type, hwaddr *pphys, int *pprot,
+                              hppa_tlb_entry **tlb_entry);
 extern const MemoryRegionOps hppa_io_eir_ops;
 extern const VMStateDescription vmstate_hppa_cpu;
 void hppa_cpu_alarm_timer(void *);
diff --git a/target/hppa/helper.h b/target/hppa/helper.h
index c7e35ce8c7..647f043c85 100644
--- a/target/hppa/helper.h
+++ b/target/hppa/helper.h
@@ -95,4 +95,5 @@ DEF_HELPER_FLAGS_2(ptlb, TCG_CALL_NO_RWG, void, env, tl)
 DEF_HELPER_FLAGS_1(ptlbe, TCG_CALL_NO_RWG, void, env)
 DEF_HELPER_FLAGS_2(lpa, TCG_CALL_NO_WG, tr, env, tl)
 DEF_HELPER_FLAGS_1(change_prot_id, TCG_CALL_NO_RWG, void, env)
+DEF_HELPER_1(diag_btlb, void, env)
 #endif
diff --git a/target/hppa/insns.decode b/target/hppa/insns.decode
index 27341d27b2..aebe03ccfd 100644
--- a/target/hppa/insns.decode
+++ b/target/hppa/insns.decode
@@ -528,4 +528,4 @@ fdiv_d          001110 ..... ..... 011 ..... ... .....  @f0e_d_3
 xmpyu           001110 ..... ..... 010 .0111 .00 t:5    r1=%ra64 r2=%rb64
 
 # diag
-diag            000101 ----- ----- ---- ---- ---- ----
+diag            000101 i:26
diff --git a/target/hppa/int_helper.c b/target/hppa/int_helper.c
index bebc732c97..3ab9934a1d 100644
--- a/target/hppa/int_helper.c
+++ b/target/hppa/int_helper.c
@@ -154,7 +154,7 @@ void hppa_cpu_do_interrupt(CPUState *cs)
 
                     vaddr = hppa_form_gva_psw(old_psw, iasq_f, vaddr);
                     t = hppa_get_physical_address(env, vaddr, MMU_KERNEL_IDX,
-                                                  0, &paddr, &prot);
+                                                  0, &paddr, &prot, NULL);
                     if (t >= 0) {
                         /* We can't re-load the instruction.  */
                         env->cr[CR_IIR] = 0;
diff --git a/target/hppa/mem_helper.c b/target/hppa/mem_helper.c
index 46c3dcaf15..520fd311f8 100644
--- a/target/hppa/mem_helper.c
+++ b/target/hppa/mem_helper.c
@@ -41,16 +41,24 @@ static hppa_tlb_entry *hppa_find_tlb(CPUHPPAState *env, vaddr addr)
     return NULL;
 }
 
-static void hppa_flush_tlb_ent(CPUHPPAState *env, hppa_tlb_entry *ent)
+static void hppa_flush_tlb_ent(CPUHPPAState *env, hppa_tlb_entry *ent,
+                               bool force_flush_btlb)
 {
     CPUState *cs = env_cpu(env);
-    unsigned i, n = 1 << (2 * ent->page_size);
-    uint64_t addr = ent->va_b;
+
+    if (!ent->entry_valid) {
+        return;
+    }
 
     trace_hppa_tlb_flush_ent(env, ent, ent->va_b, ent->va_e, ent->pa);
 
-    for (i = 0; i < n; ++i, addr += TARGET_PAGE_SIZE) {
-        tlb_flush_page_by_mmuidx(cs, addr, HPPA_MMU_FLUSH_MASK);
+    tlb_flush_range_by_mmuidx(cs, ent->va_b,
+                                ent->va_e - ent->va_b + 1,
+                                HPPA_MMU_FLUSH_MASK, TARGET_LONG_BITS);
+
+    /* never clear BTLBs, unless forced to do so. */
+    if (ent < &env->tlb[HPPA_BTLB_ENTRIES] && !force_flush_btlb) {
+        return;
     }
 
     memset(ent, 0, sizeof(*ent));
@@ -60,23 +68,35 @@ static void hppa_flush_tlb_ent(CPUHPPAState *env, hppa_tlb_entry *ent)
 static hppa_tlb_entry *hppa_alloc_tlb_ent(CPUHPPAState *env)
 {
     hppa_tlb_entry *ent;
-    uint32_t i = env->tlb_last;
+    uint32_t i;
+
+    if (env->tlb_last < HPPA_BTLB_ENTRIES || env->tlb_last >= ARRAY_SIZE(env->tlb)) {
+        i = HPPA_BTLB_ENTRIES;
+        env->tlb_last = HPPA_BTLB_ENTRIES + 1;
+    } else {
+        i = env->tlb_last;
+        env->tlb_last++;
+    }
 
-    env->tlb_last = (i == ARRAY_SIZE(env->tlb) - 1 ? 0 : i + 1);
     ent = &env->tlb[i];
 
-    hppa_flush_tlb_ent(env, ent);
+    hppa_flush_tlb_ent(env, ent, false);
     return ent;
 }
 
 int hppa_get_physical_address(CPUHPPAState *env, vaddr addr, int mmu_idx,
-                              int type, hwaddr *pphys, int *pprot)
+                              int type, hwaddr *pphys, int *pprot,
+                              hppa_tlb_entry **tlb_entry)
 {
     hwaddr phys;
     int prot, r_prot, w_prot, x_prot, priv;
     hppa_tlb_entry *ent;
     int ret = -1;
 
+    if (tlb_entry) {
+        *tlb_entry = NULL;
+    }
+
     /* Virtual translation disabled.  Direct map virtual to physical.  */
     if (mmu_idx == MMU_PHYS_IDX) {
         phys = addr;
@@ -93,8 +113,12 @@ int hppa_get_physical_address(CPUHPPAState *env, vaddr addr, int mmu_idx,
         goto egress;
     }
 
+    if (tlb_entry) {
+        *tlb_entry = ent;
+    }
+
     /* We now know the physical address.  */
-    phys = ent->pa + (addr & ~TARGET_PAGE_MASK);
+    phys = ent->pa + (addr - ent->va_b);
 
     /* Map TLB access_rights field to QEMU protection.  */
     priv = MMU_IDX_TO_PRIV(mmu_idx);
@@ -193,7 +217,7 @@ hwaddr hppa_cpu_get_phys_page_debug(CPUState *cs, vaddr addr)
     }
 
     excp = hppa_get_physical_address(&cpu->env, addr, MMU_KERNEL_IDX, 0,
-                                     &phys, &prot);
+                                     &phys, &prot, NULL);
 
     /* Since we're translating for debugging, the only error that is a
        hard error is no translation at all.  Otherwise, while a real cpu
@@ -207,6 +231,7 @@ bool hppa_cpu_tlb_fill(CPUState *cs, vaddr addr, int size,
 {
     HPPACPU *cpu = HPPA_CPU(cs);
     CPUHPPAState *env = &cpu->env;
+    hppa_tlb_entry *ent;
     int prot, excp, a_prot;
     hwaddr phys;
 
@@ -223,7 +248,7 @@ bool hppa_cpu_tlb_fill(CPUState *cs, vaddr addr, int size,
     }
 
     excp = hppa_get_physical_address(env, addr, mmu_idx,
-                                     a_prot, &phys, &prot);
+                                     a_prot, &phys, &prot, &ent);
     if (unlikely(excp >= 0)) {
         if (probe) {
             return false;
@@ -243,7 +268,7 @@ bool hppa_cpu_tlb_fill(CPUState *cs, vaddr addr, int size,
                                 phys & TARGET_PAGE_MASK, size, type, mmu_idx);
     /* Success!  Store the translation into the QEMU TLB.  */
     tlb_set_page(cs, addr & TARGET_PAGE_MASK, phys & TARGET_PAGE_MASK,
-                 prot, mmu_idx, TARGET_PAGE_SIZE);
+                 prot, mmu_idx, TARGET_PAGE_SIZE << (ent ? 2 * ent->page_size : 0));
     return true;
 }
 
@@ -254,11 +279,11 @@ void HELPER(itlba)(CPUHPPAState *env, target_ulong addr, target_ureg reg)
     int i;
 
     /* Zap any old entries covering ADDR; notice empty entries on the way.  */
-    for (i = 0; i < ARRAY_SIZE(env->tlb); ++i) {
+    for (i = HPPA_BTLB_ENTRIES; i < ARRAY_SIZE(env->tlb); ++i) {
         hppa_tlb_entry *ent = &env->tlb[i];
         if (ent->va_b <= addr && addr <= ent->va_e) {
             if (ent->entry_valid) {
-                hppa_flush_tlb_ent(env, ent);
+                hppa_flush_tlb_ent(env, ent, false);
             }
             if (!empty) {
                 empty = ent;
@@ -278,16 +303,8 @@ void HELPER(itlba)(CPUHPPAState *env, target_ulong addr, target_ureg reg)
     trace_hppa_tlb_itlba(env, empty, empty->va_b, empty->va_e, empty->pa);
 }
 
-/* Insert (Insn/Data) TLB Protection.  Note this is PA 1.1 only.  */
-void HELPER(itlbp)(CPUHPPAState *env, target_ulong addr, target_ureg reg)
+static void set_access_bits(CPUHPPAState *env, hppa_tlb_entry *ent, target_ureg reg)
 {
-    hppa_tlb_entry *ent = hppa_find_tlb(env, addr);
-
-    if (unlikely(ent == NULL)) {
-        qemu_log_mask(LOG_GUEST_ERROR, "ITLBP not following ITLBA\n");
-        return;
-    }
-
     ent->access_id = extract32(reg, 1, 18);
     ent->u = extract32(reg, 19, 1);
     ent->ar_pl2 = extract32(reg, 20, 2);
@@ -301,6 +318,19 @@ void HELPER(itlbp)(CPUHPPAState *env, target_ulong addr, target_ureg reg)
                          ent->ar_pl1, ent->ar_type, ent->b, ent->d, ent->t);
 }
 
+/* Insert (Insn/Data) TLB Protection.  Note this is PA 1.1 only.  */
+void HELPER(itlbp)(CPUHPPAState *env, target_ulong addr, target_ureg reg)
+{
+    hppa_tlb_entry *ent = hppa_find_tlb(env, addr);
+
+    if (unlikely(ent == NULL)) {
+        qemu_log_mask(LOG_GUEST_ERROR, "ITLBP not following ITLBA\n");
+        return;
+    }
+
+    set_access_bits(env, ent, reg);
+}
+
 /* Purge (Insn/Data) TLB.  This is explicitly page-based, and is
    synchronous across all processors.  */
 static void ptlb_work(CPUState *cpu, run_on_cpu_data data)
@@ -310,7 +340,7 @@ static void ptlb_work(CPUState *cpu, run_on_cpu_data data)
     hppa_tlb_entry *ent = hppa_find_tlb(env, addr);
 
     if (ent && ent->entry_valid) {
-        hppa_flush_tlb_ent(env, ent);
+        hppa_flush_tlb_ent(env, ent, false);
     }
 }
 
@@ -334,7 +364,10 @@ void HELPER(ptlb)(CPUHPPAState *env, target_ulong addr)
 void HELPER(ptlbe)(CPUHPPAState *env)
 {
     trace_hppa_tlb_ptlbe(env);
-    memset(env->tlb, 0, sizeof(env->tlb));
+    qemu_log_mask(CPU_LOG_MMU, "FLUSH ALL TLB ENTRIES\n");
+    memset(&env->tlb[HPPA_BTLB_ENTRIES], 0,
+        sizeof(env->tlb) - HPPA_BTLB_ENTRIES * sizeof(env->tlb[0]));
+    env->tlb_last = HPPA_BTLB_ENTRIES;
     tlb_flush_by_mmuidx(env_cpu(env), HPPA_MMU_FLUSH_MASK);
 }
 
@@ -356,7 +389,7 @@ target_ureg HELPER(lpa)(CPUHPPAState *env, target_ulong addr)
     int prot, excp;
 
     excp = hppa_get_physical_address(env, addr, MMU_KERNEL_IDX, 0,
-                                     &phys, &prot);
+                                     &phys, &prot, NULL);
     if (excp >= 0) {
         if (env->psw & PSW_Q) {
             /* ??? Needs tweaking for hppa64.  */
@@ -379,3 +412,95 @@ int hppa_artype_for_page(CPUHPPAState *env, target_ulong vaddr)
     hppa_tlb_entry *ent = hppa_find_tlb(env, vaddr);
     return ent ? ent->ar_type : -1;
 }
+
+/*
+ * diag_btlb() emulates the PDC PDC_BLOCK_TLB firmware call to
+ * allow operating systems to modify the Block TLB (BTLB) entries.
+ * For implementation details see page 1-13 in
+ * https://parisc.wiki.kernel.org/images-parisc/e/ef/Pdc11-v0.96-Ch1-procs.pdf
+ */
+void HELPER(diag_btlb)(CPUHPPAState *env)
+{
+    unsigned int phys_page, len, slot;
+    int mmu_idx = cpu_mmu_index(env, 0);
+    uintptr_t ra = GETPC();
+    hppa_tlb_entry *btlb;
+    uint64_t virt_page;
+    uint32_t *vaddr;
+
+#ifdef TARGET_HPPA64
+    /* BTLBs are not supported on 64-bit CPUs */
+    env->gr[28] = -1; /* nonexistent procedure */
+    return;
+#endif
+    env->gr[28] = 0; /* PDC_OK */
+
+    switch (env->gr[25]) {
+    case 0:
+        /* return BTLB parameters */
+        qemu_log_mask(CPU_LOG_MMU, "PDC_BLOCK_TLB: PDC_BTLB_INFO\n");
+        vaddr = probe_access(env, env->gr[24], 4 * sizeof(target_ulong),
+                             MMU_DATA_STORE, mmu_idx, ra);
+        if (vaddr == NULL) {
+            env->gr[28] = -10; /* invalid argument */
+        } else {
+            vaddr[0] = cpu_to_be32(1);
+            vaddr[1] = cpu_to_be32(16 * 1024);
+            vaddr[2] = cpu_to_be32(HPPA_BTLB_FIXED);
+            vaddr[3] = cpu_to_be32(HPPA_BTLB_VARIABLE);
+        }
+        break;
+    case 1:
+        /* insert BTLB entry */
+        virt_page = env->gr[24];        /* upper 32 bits */
+        virt_page <<= 32;
+        virt_page |= env->gr[23];       /* lower 32 bits */
+        phys_page = env->gr[22];
+        len = env->gr[21];
+        slot = env->gr[19];
+        qemu_log_mask(CPU_LOG_MMU, "PDC_BLOCK_TLB: PDC_BTLB_INSERT "
+                    "0x%08llx-0x%08llx: vpage 0x%llx for phys page 0x%04x len %d "
+                    "into slot %d\n",
+                    (long long) virt_page << TARGET_PAGE_BITS,
+                    (long long) (virt_page + len) << TARGET_PAGE_BITS,
+                    (long long) virt_page, phys_page, len, slot);
+        if (slot < HPPA_BTLB_ENTRIES) {
+            btlb = &env->tlb[slot];
+            /* force flush of possibly existing BTLB entry */
+            hppa_flush_tlb_ent(env, btlb, true);
+            /* create new BTLB entry */
+            btlb->va_b = virt_page << TARGET_PAGE_BITS;
+            btlb->va_e = btlb->va_b + len * TARGET_PAGE_SIZE - 1;
+            btlb->pa = phys_page << TARGET_PAGE_BITS;
+            set_access_bits(env, btlb, env->gr[20]);
+            btlb->t = 0;
+            btlb->d = 1;
+        } else {
+            env->gr[28] = -10; /* invalid argument */
+        }
+        break;
+    case 2:
+        /* Purge BTLB entry */
+        slot = env->gr[22];
+        qemu_log_mask(CPU_LOG_MMU, "PDC_BLOCK_TLB: PDC_BTLB_PURGE slot %d\n",
+                                    slot);
+        if (slot < HPPA_BTLB_ENTRIES) {
+            btlb = &env->tlb[slot];
+            hppa_flush_tlb_ent(env, btlb, true);
+        } else {
+            env->gr[28] = -10; /* invalid argument */
+        }
+        break;
+    case 3:
+        /* Purge all BTLB entries */
+        qemu_log_mask(CPU_LOG_MMU, "PDC_BLOCK_TLB: PDC_BTLB_PURGE_ALL\n");
+        for (slot = 0; slot < HPPA_BTLB_ENTRIES; slot++) {
+            btlb = &env->tlb[slot];
+            hppa_flush_tlb_ent(env, btlb, true);
+        }
+        break;
+    default:
+        env->gr[28] = -2; /* nonexistent option */
+        break;
+    }
+}
diff --git a/target/hppa/op_helper.c b/target/hppa/op_helper.c
index f25a5a72aa..837e2b3117 100644
--- a/target/hppa/op_helper.c
+++ b/target/hppa/op_helper.c
@@ -179,7 +179,8 @@ target_ureg HELPER(probe)(CPUHPPAState *env, target_ulong addr,
         return 0;
     }
 
-    excp = hppa_get_physical_address(env, addr, level, 0, &phys, &prot);
+    excp = hppa_get_physical_address(env, addr, level, 0, &phys,
+                                     &prot, NULL);
     if (excp >= 0) {
         if (env->psw & PSW_Q) {
             /* ??? Needs tweaking for hppa64.  */
diff --git a/target/hppa/translate.c b/target/hppa/translate.c
index c04dc15228..650bbcfe95 100644
--- a/target/hppa/translate.c
+++ b/target/hppa/translate.c
@@ -4042,9 +4042,18 @@ static bool trans_fmpyfadd_d(DisasContext *ctx, arg_fmpyfadd_d *a)
 
 static bool trans_diag(DisasContext *ctx, arg_diag *a)
 {
-    qemu_log_mask(LOG_UNIMP, "DIAG opcode ignored\n");
-    cond_free(&ctx->null_cond);
-    return true;
+    nullify_over(ctx);
+    CHECK_MOST_PRIVILEGED(EXCP_PRIV_OPR);
+#ifndef CONFIG_USER_ONLY
+    if (a->i == 0x100) {
+        /* emulate PDC BTLB, called by SeaBIOS-hppa */
+        gen_helper_diag_btlb(cpu_env);
+    } else
+#endif
+    {
+        qemu_log_mask(LOG_UNIMP, "DIAG opcode 0x%04x ignored\n", a->i);
+    }
+    return nullify_end(ctx);
 }
 
 static void hppa_tr_init_disas_context(DisasContextBase *dcbase, CPUState *cs)