Merge tag 'pull-hex-20230105' of https://github.com/quic/qemu into staging

Hexagon update: patches from several folks

# gpg: Signature made Thu 05 Jan 2023 17:35:27 GMT
# gpg:                using RSA key 3635C788CE62B91FD4C59AB47B0244FB12DE4422
# gpg: Good signature from "Taylor Simpson (Rock on) <tsimpson@quicinc.com>" [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: 3635 C788 CE62 B91F D4C5  9AB4 7B02 44FB 12DE 4422

* tag 'pull-hex-20230105' of https://github.com/quic/qemu:
  Update scripts/meson-buildoptions.sh
  Hexagon (target/hexagon) implement mutability mask for GPRs
  target/hexagon: suppress unused variable warning
  target/hexagon/idef-parser: fix two typos in README
  tests/tcg/hexagon: fix underspecifed asm constraints
  target/hexagon: rename aliased register HEX_REG_P3_0
  linux-user/hexagon: fix signal context save & restore

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

13 files changed, 321 insertions, 31 deletions

diff --git a/linux-user/hexagon/signal.c b/linux-user/hexagon/signal.c
index ad4e3822d5..60fa7e1bce 100644
--- a/linux-user/hexagon/signal.c
+++ b/linux-user/hexagon/signal.c
@@ -39,15 +39,12 @@ struct target_sigcontext {
     target_ulong m0;
     target_ulong m1;
     target_ulong usr;
-    target_ulong p3_0;
     target_ulong gp;
     target_ulong ugp;
     target_ulong pc;
     target_ulong cause;
     target_ulong badva;
-    target_ulong pad1;
-    target_ulong pad2;
-    target_ulong pad3;
+    target_ulong pred[NUM_PREGS];
 };
 
 struct target_ucontext {
@@ -118,10 +115,14 @@ static void setup_sigcontext(struct target_sigcontext *sc, CPUHexagonState *env)
     __put_user(env->gpr[HEX_REG_M0], &sc->m0);
     __put_user(env->gpr[HEX_REG_M1], &sc->m1);
     __put_user(env->gpr[HEX_REG_USR], &sc->usr);
-    __put_user(env->gpr[HEX_REG_P3_0], &sc->p3_0);
     __put_user(env->gpr[HEX_REG_GP], &sc->gp);
     __put_user(env->gpr[HEX_REG_UGP], &sc->ugp);
     __put_user(env->gpr[HEX_REG_PC], &sc->pc);
+
+    int i;
+    for (i = 0; i < NUM_PREGS; i++) {
+        __put_user(env->pred[i], &(sc->pred[i]));
+    }
 }
 
 static void setup_ucontext(struct target_ucontext *uc,
@@ -230,10 +231,14 @@ static void restore_sigcontext(CPUHexagonState *env,
     __get_user(env->gpr[HEX_REG_M0], &sc->m0);
     __get_user(env->gpr[HEX_REG_M1], &sc->m1);
     __get_user(env->gpr[HEX_REG_USR], &sc->usr);
-    __get_user(env->gpr[HEX_REG_P3_0], &sc->p3_0);
     __get_user(env->gpr[HEX_REG_GP], &sc->gp);
     __get_user(env->gpr[HEX_REG_UGP], &sc->ugp);
     __get_user(env->gpr[HEX_REG_PC], &sc->pc);
+
+    int i;
+    for (i = 0; i < NUM_PREGS; i++) {
+        __get_user(env->pred[i], &(sc->pred[i]));
+    }
 }
 
 static void restore_ucontext(CPUHexagonState *env, struct target_ucontext *uc)
diff --git a/scripts/meson-buildoptions.sh b/scripts/meson-buildoptions.sh
index aa6e30ea91..0f71e92dcb 100644
--- a/scripts/meson-buildoptions.sh
+++ b/scripts/meson-buildoptions.sh
@@ -10,6 +10,9 @@ meson_options_help() {
   printf "%s\n" '                           affects only QEMU, not tools like qemu-img)'
   printf "%s\n" '  --datadir=VALUE          Data file directory [share]'
   printf "%s\n" '  --disable-coroutine-pool coroutine freelist (better performance)'
+  printf "%s\n" '  --disable-hexagon-idef-parser'
+  printf "%s\n" '                           use idef-parser to automatically generate TCG'
+  printf "%s\n" '                           code for the Hexagon frontend'
   printf "%s\n" '  --disable-install-blobs  install provided firmware blobs'
   printf "%s\n" '  --docdir=VALUE           Base directory for documentation installation'
   printf "%s\n" '                           (can be empty) [share/doc]'
@@ -40,7 +43,8 @@ meson_options_help() {
   printf "%s\n" '  --enable-trace-backends=CHOICES'
   printf "%s\n" '                           Set available tracing backends [log] (choices:'
   printf "%s\n" '                           dtrace/ftrace/log/nop/simple/syslog/ust)'
-  printf "%s\n" '  --firmwarepath=VALUES    search PATH for firmware files [share/qemu-firmware]'
+  printf "%s\n" '  --firmwarepath=VALUES    search PATH for firmware files [share/qemu-'
+  printf "%s\n" '                           firmware]'
   printf "%s\n" '  --iasl=VALUE             Path to ACPI disassembler'
   printf "%s\n" '  --includedir=VALUE       Header file directory [include]'
   printf "%s\n" '  --interp-prefix=VALUE    where to find shared libraries etc., use %M for'
@@ -93,7 +97,7 @@ meson_options_help() {
   printf "%s\n" '  glusterfs       Glusterfs block device driver'
   printf "%s\n" '  gnutls          GNUTLS cryptography support'
   printf "%s\n" '  gtk             GTK+ user interface'
-  printf "%s\n" '  gtk-clipboard   clipboard support for GTK (EXPERIMENTAL, MAY HANG)'
+  printf "%s\n" '  gtk-clipboard   clipboard support for the gtk UI (EXPERIMENTAL, MAY HANG)'
   printf "%s\n" '  guest-agent     Build QEMU Guest Agent'
   printf "%s\n" '  guest-agent-msi Build MSI package for the QEMU Guest Agent'
   printf "%s\n" '  hax             HAX acceleration support'
@@ -156,6 +160,8 @@ meson_options_help() {
   printf "%s\n" '  usb-redir       libusbredir support'
   printf "%s\n" '  vde             vde network backend support'
   printf "%s\n" '  vdi             vdi image format support'
+  printf "%s\n" '  vduse-blk-export'
+  printf "%s\n" '                  VDUSE block export support'
   printf "%s\n" '  vfio-user-server'
   printf "%s\n" '                  vfio-user server support'
   printf "%s\n" '  vhost-crypto    vhost-user crypto backend support'
@@ -164,8 +170,6 @@ meson_options_help() {
   printf "%s\n" '  vhost-user      vhost-user backend support'
   printf "%s\n" '  vhost-user-blk-server'
   printf "%s\n" '                  build vhost-user-blk server'
-  printf "%s\n" '  vduse-blk-export'
-  printf "%s\n" '                  VDUSE block export support'
   printf "%s\n" '  vhost-vdpa      vhost-vdpa kernel backend support'
   printf "%s\n" '  virglrenderer   virgl rendering support'
   printf "%s\n" '  virtfs          virtio-9p support'
@@ -283,6 +287,8 @@ _meson_option_parse() {
     --disable-guest-agent-msi) printf "%s" -Dguest_agent_msi=disabled ;;
     --enable-hax) printf "%s" -Dhax=enabled ;;
     --disable-hax) printf "%s" -Dhax=disabled ;;
+    --enable-hexagon-idef-parser) printf "%s" -Dhexagon_idef_parser=true ;;
+    --disable-hexagon-idef-parser) printf "%s" -Dhexagon_idef_parser=false ;;
     --enable-hvf) printf "%s" -Dhvf=enabled ;;
     --disable-hvf) printf "%s" -Dhvf=disabled ;;
     --iasl=*) quote_sh "-Diasl=$2" ;;
@@ -429,6 +435,8 @@ _meson_option_parse() {
     --disable-vde) printf "%s" -Dvde=disabled ;;
     --enable-vdi) printf "%s" -Dvdi=enabled ;;
     --disable-vdi) printf "%s" -Dvdi=disabled ;;
+    --enable-vduse-blk-export) printf "%s" -Dvduse_blk_export=enabled ;;
+    --disable-vduse-blk-export) printf "%s" -Dvduse_blk_export=disabled ;;
     --enable-vfio-user-server) printf "%s" -Dvfio_user_server=enabled ;;
     --disable-vfio-user-server) printf "%s" -Dvfio_user_server=disabled ;;
     --enable-vhost-crypto) printf "%s" -Dvhost_crypto=enabled ;;
@@ -441,8 +449,6 @@ _meson_option_parse() {
     --disable-vhost-user) printf "%s" -Dvhost_user=disabled ;;
     --enable-vhost-user-blk-server) printf "%s" -Dvhost_user_blk_server=enabled ;;
     --disable-vhost-user-blk-server) printf "%s" -Dvhost_user_blk_server=disabled ;;
-    --enable-vduse-blk-export) printf "%s" -Dvduse_blk_export=enabled ;;
-    --disable-vduse-blk-export) printf "%s" -Dvduse_blk_export=disabled ;;
     --enable-vhost-vdpa) printf "%s" -Dvhost_vdpa=enabled ;;
     --disable-vhost-vdpa) printf "%s" -Dvhost_vdpa=disabled ;;
     --enable-virglrenderer) printf "%s" -Dvirglrenderer=enabled ;;
diff --git a/target/hexagon/cpu.c b/target/hexagon/cpu.c
index 658ca4ff78..807037c586 100644
--- a/target/hexagon/cpu.c
+++ b/target/hexagon/cpu.c
@@ -86,7 +86,7 @@ static target_ulong adjust_stack_ptrs(CPUHexagonState *env, target_ulong addr)
     return addr;
 }
 
-/* HEX_REG_P3_0 (aka C4) is an alias for the predicate registers */
+/* HEX_REG_P3_0_ALIASED (aka C4) is an alias for the predicate registers */
 static target_ulong read_p3_0(CPUHexagonState *env)
 {
     int32_t control_reg = 0;
@@ -102,7 +102,7 @@ static void print_reg(FILE *f, CPUHexagonState *env, int regnum)
 {
     target_ulong value;
 
-    if (regnum == HEX_REG_P3_0) {
+    if (regnum == HEX_REG_P3_0_ALIASED) {
         value = read_p3_0(env);
     } else {
         value = regnum < 32 ? adjust_stack_ptrs(env, env->gpr[regnum])
@@ -198,7 +198,7 @@ static void hexagon_dump(CPUHexagonState *env, FILE *f, int flags)
     print_reg(f, env, HEX_REG_M0);
     print_reg(f, env, HEX_REG_M1);
     print_reg(f, env, HEX_REG_USR);
-    print_reg(f, env, HEX_REG_P3_0);
+    print_reg(f, env, HEX_REG_P3_0_ALIASED);
     print_reg(f, env, HEX_REG_GP);
     print_reg(f, env, HEX_REG_UGP);
     print_reg(f, env, HEX_REG_PC);
diff --git a/target/hexagon/genptr.c b/target/hexagon/genptr.c
index 6cf2e0ed43..90db99024f 100644
--- a/target/hexagon/genptr.c
+++ b/target/hexagon/genptr.c
@@ -43,6 +43,33 @@ TCGv gen_read_preg(TCGv pred, uint8_t num)
     return pred;
 }
 
+#define IMMUTABLE (~0)
+
+static const target_ulong reg_immut_masks[TOTAL_PER_THREAD_REGS] = {
+    [HEX_REG_USR] = 0xc13000c0,
+    [HEX_REG_PC] = IMMUTABLE,
+    [HEX_REG_GP] = 0x3f,
+    [HEX_REG_UPCYCLELO] = IMMUTABLE,
+    [HEX_REG_UPCYCLEHI] = IMMUTABLE,
+    [HEX_REG_UTIMERLO] = IMMUTABLE,
+    [HEX_REG_UTIMERHI] = IMMUTABLE,
+};
+
+static inline void gen_masked_reg_write(TCGv new_val, TCGv cur_val,
+                                        target_ulong reg_mask)
+{
+    if (reg_mask) {
+        TCGv tmp = tcg_temp_new();
+
+        /* new_val = (new_val & ~reg_mask) | (cur_val & reg_mask) */
+        tcg_gen_andi_tl(new_val, new_val, ~reg_mask);
+        tcg_gen_andi_tl(tmp, cur_val, reg_mask);
+        tcg_gen_or_tl(new_val, new_val, tmp);
+
+        tcg_temp_free(tmp);
+    }
+}
+
 static inline void gen_log_predicated_reg_write(int rnum, TCGv val,
                                                 uint32_t slot)
 {
@@ -69,6 +96,9 @@ static inline void gen_log_predicated_reg_write(int rnum, TCGv val,
 
 void gen_log_reg_write(int rnum, TCGv val)
 {
+    const target_ulong reg_mask = reg_immut_masks[rnum];
+
+    gen_masked_reg_write(val, hex_gpr[rnum], reg_mask);
     tcg_gen_mov_tl(hex_new_value[rnum], val);
     if (HEX_DEBUG) {
         /* Do this so HELPER(debug_commit_end) will know */
@@ -114,19 +144,29 @@ static void gen_log_predicated_reg_write_pair(int rnum, TCGv_i64 val,
 
 static void gen_log_reg_write_pair(int rnum, TCGv_i64 val)
 {
+    const target_ulong reg_mask_low = reg_immut_masks[rnum];
+    const target_ulong reg_mask_high = reg_immut_masks[rnum + 1];
+    TCGv val32 = tcg_temp_new();
+
     /* Low word */
-    tcg_gen_extrl_i64_i32(hex_new_value[rnum], val);
+    tcg_gen_extrl_i64_i32(val32, val);
+    gen_masked_reg_write(val32, hex_gpr[rnum], reg_mask_low);
+    tcg_gen_mov_tl(hex_new_value[rnum], val32);
     if (HEX_DEBUG) {
         /* Do this so HELPER(debug_commit_end) will know */
         tcg_gen_movi_tl(hex_reg_written[rnum], 1);
     }
 
     /* High word */
-    tcg_gen_extrh_i64_i32(hex_new_value[rnum + 1], val);
+    tcg_gen_extrh_i64_i32(val32, val);
+    gen_masked_reg_write(val32, hex_gpr[rnum + 1], reg_mask_high);
+    tcg_gen_mov_tl(hex_new_value[rnum + 1], val32);
     if (HEX_DEBUG) {
         /* Do this so HELPER(debug_commit_end) will know */
         tcg_gen_movi_tl(hex_reg_written[rnum + 1], 1);
     }
+
+    tcg_temp_free(val32);
 }
 
 void gen_log_pred_write(DisasContext *ctx, int pnum, TCGv val)
@@ -163,7 +203,7 @@ static inline void gen_read_p3_0(TCGv control_reg)
 
 /*
  * Certain control registers require special handling on read
- *     HEX_REG_P3_0          aliased to the predicate registers
+ *     HEX_REG_P3_0_ALIASED  aliased to the predicate registers
  *                           -> concat the 4 predicate registers together
  *     HEX_REG_PC            actual value stored in DisasContext
  *                           -> assign from ctx->base.pc_next
@@ -173,7 +213,7 @@ static inline void gen_read_p3_0(TCGv control_reg)
 static inline void gen_read_ctrl_reg(DisasContext *ctx, const int reg_num,
                                      TCGv dest)
 {
-    if (reg_num == HEX_REG_P3_0) {
+    if (reg_num == HEX_REG_P3_0_ALIASED) {
         gen_read_p3_0(dest);
     } else if (reg_num == HEX_REG_PC) {
         tcg_gen_movi_tl(dest, ctx->base.pc_next);
@@ -194,7 +234,7 @@ static inline void gen_read_ctrl_reg(DisasContext *ctx, const int reg_num,
 static inline void gen_read_ctrl_reg_pair(DisasContext *ctx, const int reg_num,
                                           TCGv_i64 dest)
 {
-    if (reg_num == HEX_REG_P3_0) {
+    if (reg_num == HEX_REG_P3_0_ALIASED) {
         TCGv p3_0 = tcg_temp_new();
         gen_read_p3_0(p3_0);
         tcg_gen_concat_i32_i64(dest, p3_0, hex_gpr[reg_num + 1]);
@@ -238,7 +278,7 @@ static void gen_write_p3_0(DisasContext *ctx, TCGv control_reg)
 
 /*
  * Certain control registers require special handling on write
- *     HEX_REG_P3_0          aliased to the predicate registers
+ *     HEX_REG_P3_0_ALIASED  aliased to the predicate registers
  *                           -> break the value across 4 predicate registers
  *     HEX_REG_QEMU_*_CNT    changes in current TB in DisasContext
  *                            -> clear the changes
@@ -246,7 +286,7 @@ static void gen_write_p3_0(DisasContext *ctx, TCGv control_reg)
 static inline void gen_write_ctrl_reg(DisasContext *ctx, int reg_num,
                                       TCGv val)
 {
-    if (reg_num == HEX_REG_P3_0) {
+    if (reg_num == HEX_REG_P3_0_ALIASED) {
         gen_write_p3_0(ctx, val);
     } else {
         gen_log_reg_write(reg_num, val);
@@ -266,7 +306,7 @@ static inline void gen_write_ctrl_reg(DisasContext *ctx, int reg_num,
 static inline void gen_write_ctrl_reg_pair(DisasContext *ctx, int reg_num,
                                            TCGv_i64 val)
 {
-    if (reg_num == HEX_REG_P3_0) {
+    if (reg_num == HEX_REG_P3_0_ALIASED) {
         TCGv val32 = tcg_temp_new();
         tcg_gen_extrl_i64_i32(val32, val);
         gen_write_p3_0(ctx, val32);
diff --git a/target/hexagon/hex_regs.h b/target/hexagon/hex_regs.h
index a63c2c0fd5..bddfc28021 100644
--- a/target/hexagon/hex_regs.h
+++ b/target/hexagon/hex_regs.h
@@ -58,7 +58,7 @@ enum {
     HEX_REG_LC0              = 33,
     HEX_REG_SA1              = 34,
     HEX_REG_LC1              = 35,
-    HEX_REG_P3_0             = 36,
+    HEX_REG_P3_0_ALIASED     = 36,
     HEX_REG_M0               = 38,
     HEX_REG_M1               = 39,
     HEX_REG_USR              = 40,
diff --git a/target/hexagon/idef-parser/README.rst b/target/hexagon/idef-parser/README.rst
index 65e6bf4ee5..ff6d14150a 100644
--- a/target/hexagon/idef-parser/README.rst
+++ b/target/hexagon/idef-parser/README.rst
@@ -552,11 +552,11 @@ to compare our buggy CPU state against, running
 
 ::
 
-    meson configure -Dhexagon_idef_parser_enabled=false
+    meson configure -Dhexagon_idef_parser=false
 
 will disable the idef-parser for all instructions and fallback on manual
 tinycode generator overrides, or on helper function implementations. Recompiling
-gives us ``qemu-hexagon`` which passes all tests. If ``qemu-heaxgon-buggy`` is
+gives us ``qemu-hexagon`` which passes all tests. If ``qemu-hexagon-buggy`` is
 our binary with the incorrect tinycode generators, we can compare the CPU state
 between the two versions
 
diff --git a/target/hexagon/idef-parser/idef-parser.y b/target/hexagon/idef-parser/idef-parser.y
index 8be44a0ad1..c14cb39500 100644
--- a/target/hexagon/idef-parser/idef-parser.y
+++ b/target/hexagon/idef-parser/idef-parser.y
@@ -99,6 +99,8 @@
 /* Input file containing the description of each hexagon instruction */
 input : instructions
       {
+          /* Suppress warning about unused yynerrs */
+          (void) yynerrs;
           YYACCEPT;
       }
       ;
diff --git a/target/hexagon/meson.build b/target/hexagon/meson.build
index e8f250fcac..c9d31d095c 100644
--- a/target/hexagon/meson.build
+++ b/target/hexagon/meson.build
@@ -197,7 +197,6 @@ if idef_parser_enabled and 'hexagon-linux-user' in target_dirs
          idef_parser_dir / 'parser-helpers.c'],
         include_directories: ['idef-parser', '../../include/'],
         dependencies: [glib_dep],
-        c_args: ['-Wextra'],
         native: true
     )
 
diff --git a/tests/tcg/hexagon/Makefile.target b/tests/tcg/hexagon/Makefile.target
index 9ee1faa1e1..18e6a5969e 100644
--- a/tests/tcg/hexagon/Makefile.target
+++ b/tests/tcg/hexagon/Makefile.target
@@ -43,6 +43,8 @@ HEX_TESTS += load_align
 HEX_TESTS += atomics
 HEX_TESTS += fpstuff
 HEX_TESTS += overflow
+HEX_TESTS += signal_context
+HEX_TESTS += reg_mut
 
 HEX_TESTS += test_abs
 HEX_TESTS += test_bitcnt
diff --git a/tests/tcg/hexagon/mem_noshuf.c b/tests/tcg/hexagon/mem_noshuf.c
index 0f4064e700..210b2f1208 100644
--- a/tests/tcg/hexagon/mem_noshuf.c
+++ b/tests/tcg/hexagon/mem_noshuf.c
@@ -144,7 +144,7 @@ static inline long long pred_ld_sd_pi(int pred, long long *p, long long *q,
                  "}:mem_noshuf\n"
                  : "=&r"(ret)
                  : "r"(p), "r"(q), "r"(x), "r"(y), "r"(pred)
-                 : "p0", "memory");
+                 : "r7", "p0", "memory");
     return ret;
 }
 
diff --git a/tests/tcg/hexagon/misc.c b/tests/tcg/hexagon/misc.c
index f0b1947fb3..e73ab57334 100644
--- a/tests/tcg/hexagon/misc.c
+++ b/tests/tcg/hexagon/misc.c
@@ -186,10 +186,10 @@ static int L2_ploadrifnew_pi(void *p, int pred)
   int result;
   asm volatile("%0 = #31\n\t"
                "{\n\t"
-               "    p0 = cmp.eq(%1, #1)\n\t"
-               "    if (!p0.new) %0 = memw(%2++#4)\n\t"
+               "    p0 = cmp.eq(%2, #1)\n\t"
+               "    if (!p0.new) %0 = memw(%1++#4)\n\t"
                "}\n\t"
-               : "=r"(result) : "r"(pred), "r"(p)
+               : "=&r"(result), "+r"(p) : "r"(pred)
                : "p0");
   return result;
 }
diff --git a/tests/tcg/hexagon/reg_mut.c b/tests/tcg/hexagon/reg_mut.c
new file mode 100644
index 0000000000..910e663ace
--- /dev/null
+++ b/tests/tcg/hexagon/reg_mut.c
@@ -0,0 +1,152 @@
+
+/*
+ *  Copyright(c) 2022 Qualcomm Innovation Center, Inc. All Rights Reserved.
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdio.h>
+#include <stdint.h>
+
+static int err;
+
+#define check(N, EXPECT) \
+    do { \
+        uint64_t value = N; \
+        uint64_t expect = EXPECT; \
+        if (value != EXPECT) { \
+            printf("ERROR: \"%s\" 0x%04llx != 0x%04llx at %s:%d\n", #N, value, \
+                   expect, __FILE__, __LINE__); \
+            err++; \
+        } \
+    } while (0)
+
+#define check_ne(N, EXPECT) \
+    do { \
+        uint64_t value = N; \
+        uint64_t expect = EXPECT; \
+        if (value == EXPECT) { \
+            printf("ERROR: \"%s\" 0x%04llx == 0x%04llx at %s:%d\n", #N, value, \
+                   expect, __FILE__, __LINE__); \
+            err++; \
+        } \
+    } while (0)
+
+#define WRITE_REG_NOCLOBBER(output, reg_name, input) \
+    asm volatile(reg_name " = %1\n\t" \
+                 "%0 = " reg_name "\n\t" \
+                 : "=r"(output) \
+                 : "r"(input) \
+                 : );
+
+#define WRITE_REG_ENCODED(output, reg_name, input, encoding) \
+    asm volatile("r0 = %1\n\t" \
+                 encoding "\n\t" \
+                 "%0 = " reg_name "\n\t" \
+                 : "=r"(output) \
+                 : "r"(input) \
+                 : "r0");
+
+#define WRITE_REG_PAIR_ENCODED(output, reg_name, input, encoding) \
+    asm volatile("r1:0 = %1\n\t" \
+                 encoding "\n\t" \
+                 "%0 = " reg_name "\n\t" \
+                 : "=r"(output) \
+                 : "r"(input) \
+                 : "r1:0");
+
+/*
+ * Instruction word: { pc = r0 }
+ *
+ * This instruction is barred by the assembler.
+ *
+ *    3                   2                   1
+ *  1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * |    Opc[A2_tfrrcr]   | Src[R0] |P P|                 |  C9/PC  |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ */
+#define PC_EQ_R0        ".word 0x6220c009"
+#define C9_8_EQ_R1_0    ".word 0x6320c008"
+
+static inline void write_control_registers(void)
+{
+    uint32_t result = 0;
+
+    WRITE_REG_NOCLOBBER(result, "usr", 0xffffffff);
+    check(result, 0x3ecfff3f);
+
+    WRITE_REG_NOCLOBBER(result, "gp", 0xffffffff);
+    check(result, 0xffffffc0);
+
+    WRITE_REG_NOCLOBBER(result, "upcyclelo", 0xffffffff);
+    check(result, 0x00000000);
+
+    WRITE_REG_NOCLOBBER(result, "upcyclehi", 0xffffffff);
+    check(result, 0x00000000);
+
+    WRITE_REG_NOCLOBBER(result, "utimerlo", 0xffffffff);
+    check(result, 0x00000000);
+
+    WRITE_REG_NOCLOBBER(result, "utimerhi", 0xffffffff);
+    check(result, 0x00000000);
+
+    /*
+     * PC is special.  Setting it to these values
+     * should cause a catastrophic failure.
+     */
+    WRITE_REG_ENCODED(result, "pc", 0x00000000, PC_EQ_R0);
+    check_ne(result, 0x00000000);
+
+    WRITE_REG_ENCODED(result, "pc", 0x00000001, PC_EQ_R0);
+    check_ne(result, 0x00000001);
+
+    WRITE_REG_ENCODED(result, "pc", 0xffffffff, PC_EQ_R0);
+    check_ne(result, 0xffffffff);
+}
+
+static inline void write_control_register_pairs(void)
+{
+    uint64_t result = 0;
+
+    WRITE_REG_NOCLOBBER(result, "c11:10", 0xffffffffffffffff);
+    check(result, 0xffffffc0ffffffff);
+
+    WRITE_REG_NOCLOBBER(result, "c15:14", 0xffffffffffffffff);
+    check(result, 0x0000000000000000);
+
+    WRITE_REG_NOCLOBBER(result, "c31:30", 0xffffffffffffffff);
+    check(result, 0x0000000000000000);
+
+    WRITE_REG_PAIR_ENCODED(result, "c9:8", (uint64_t) 0x0000000000000000,
+                           C9_8_EQ_R1_0);
+    check_ne(result, 0x000000000000000);
+
+    WRITE_REG_PAIR_ENCODED(result, "c9:8", 0x0000000100000000, C9_8_EQ_R1_0);
+    check_ne(result, 0x0000000100000000);
+
+    WRITE_REG_PAIR_ENCODED(result, "c9:8", 0xffffffffffffffff, C9_8_EQ_R1_0);
+    check_ne(result, 0xffffffffffffffff);
+}
+
+int main()
+{
+    err = 0;
+
+    write_control_registers();
+    write_control_register_pairs();
+
+    puts(err ? "FAIL" : "PASS");
+    return err;
+}
diff --git a/tests/tcg/hexagon/signal_context.c b/tests/tcg/hexagon/signal_context.c
new file mode 100644
index 0000000000..7202fa64b6
--- /dev/null
+++ b/tests/tcg/hexagon/signal_context.c
@@ -0,0 +1,84 @@
+/*
+ *  Copyright(c) 2022 Qualcomm Innovation Center, Inc. All Rights Reserved.
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdio.h>
+#include <signal.h>
+#include <time.h>
+
+void sig_user(int sig, siginfo_t *info, void *puc)
+{
+    asm("r7 = #0\n\t"
+        "p0 = r7\n\t"
+        "p1 = r7\n\t"
+        "p2 = r7\n\t"
+        "p3 = r7\n\t"
+        : : : "r7", "p0", "p1", "p2", "p3");
+}
+
+int main()
+{
+    int err = 0;
+    unsigned int i = 100000;
+    struct sigaction act;
+    struct itimerspec it;
+    timer_t tid;
+    struct sigevent sev;
+
+    act.sa_sigaction = sig_user;
+    sigemptyset(&act.sa_mask);
+    act.sa_flags = SA_SIGINFO;
+    sigaction(SIGUSR1, &act, NULL);
+    sev.sigev_notify = SIGEV_SIGNAL;
+    sev.sigev_signo = SIGUSR1;
+    sev.sigev_value.sival_ptr = &tid;
+    timer_create(CLOCK_REALTIME, &sev, &tid);
+    it.it_interval.tv_sec = 0;
+    it.it_interval.tv_nsec = 100000;
+    it.it_value.tv_sec = 0;
+    it.it_value.tv_nsec = 100000;
+    timer_settime(tid, 0, &it, NULL);
+
+    asm("loop0(1f, %1)\n\t"
+        "1: r8 = #0xff\n\t"
+        "   p0 = r8\n\t"
+        "   p1 = r8\n\t"
+        "   p2 = r8\n\t"
+        "   p3 = r8\n\t"
+        "   jump 3f\n\t"
+        "2: memb(%0) = #1\n\t"
+        "   jump 4f\n\t"
+        "3:\n\t"
+        "   r8 = p0\n\t"
+        "   p0 = cmp.eq(r8, #0xff)\n\t"
+        "   if (!p0) jump 2b\n\t"
+        "   r8 = p1\n\t"
+        "   p0 = cmp.eq(r8, #0xff)\n\t"
+        "   if (!p0) jump 2b\n\t"
+        "   r8 = p2\n\t"
+        "   p0 = cmp.eq(r8, #0xff)\n\t"
+        "   if (!p0) jump 2b\n\t"
+        "   r8 = p3\n\t"
+        "   p0 = cmp.eq(r8, #0xff)\n\t"
+        "   if (!p0) jump 2b\n\t"
+        "4: {}: endloop0\n\t"
+        :
+        : "r"(&err), "r"(i)
+        : "memory", "r8", "p0", "p1", "p2", "p3");
+
+    puts(err ? "FAIL" : "PASS");
+    return err;
+}