Use FVP models to test v8.1-M libraries with PACBTI (#506)

QEMU doesn't currently support the M-profile PACBTI extension, so we
need to use FVP models to test those libraries. There are also other
targets not supported by QEMU, such as v8-R, which we will need these
for.

These models are available free of cost (though not open source) from
Arm, and the user must agree to a EULA before using them. I've added a
script `fvp/get_fvps.sh' to download and extract them into the `fvp'
directory.

These models are currently only used for the v8.1-M libraries with
PACBTI, but the script also downloads the AEMv8A and AEMv8R models for
future use. If the FVPs aren't installed, then the CMakeLists.txt will
skip any tests which need them. I don't think it's worth preserving the
ability to run these tests with QEMU, because we still have the
non-PACBTI library variants which are run with QEMU. The two models also
have different memory maps and require different scatter files, so if we
wanted the ability to run tests for one library on both then we'd need
to add a way to build multiple linker scripts.

Author: ostannard

.gitignore

@@ -11,3 +11,7 @@ __pycache__
 # IDEs
 .vscode
 compile_commands.json
+
+# Downloaded FVPs
+/fvp/download/
+/fvp/install/

CMakeLists.txt

@@ -134,7 +134,14 @@ option(
     the tools every time you update llvm-project."
     ON
 )
-
+set(
+    FVP_INSTALL_DIR
+    "${CMAKE_CURRENT_SOURCE_DIR}/fvp/install" CACHE STRING
+    "The directory in which the FVP models are installed. These are not
+    included in this repository, but can be downloaded by the script
+    fvp/get_fvps.sh"
+)
+set(FVP_CONFIG_DIR "${CMAKE_CURRENT_SOURCE_DIR}/fvp/config")
 set(LLVM_TOOLCHAIN_C_LIBRARY
     "picolibc" CACHE STRING
     "Which C library to use."
@@ -644,7 +651,7 @@ set(LLVM_DEFAULT_EXTERNAL_LIT "${LLVM_BINARY_DIR}/bin/llvm-lit")
 
 add_custom_target(check-newlib) # FIXME: put things in this
 
-function(get_test_executor_params target_triple qemu_machine qemu_cpu qemu_params)
+function(get_qemu_params target_triple qemu_machine qemu_cpu qemu_params)
     if(target_triple MATCHES "^aarch64")
         set(qemu_command "qemu-system-aarch64")
     else()
@@ -668,6 +675,24 @@ function(get_test_executor_params target_triple qemu_machine qemu_cpu qemu_param
     set(test_executor_params "${test_executor_params}" PARENT_SCOPE)
 endfunction()
 
+function(get_fvp_params fvp_model fvp_config)
+    set(
+        test_executor_params
+        --fvp-install-dir ${FVP_INSTALL_DIR}
+        --fvp-config-dir ${FVP_CONFIG_DIR}
+        --fvp-model ${fvp_model}
+    )
+    string(REPLACE " " ";" fvp_config_list ${fvp_config})
+    foreach(cfg ${fvp_config_list})
+          set(
+              test_executor_params
+              ${test_executor_params}
+              --fvp-config ${cfg}
+          )
+    endforeach()
+    set(test_executor_params "${test_executor_params}" PARENT_SCOPE)
+endfunction()
+
 function(
     add_picolibc
     directory
@@ -1328,9 +1353,12 @@ function(add_library_variant target_arch)
         COMPILE_FLAGS
         MULTILIB_FLAGS
         PICOLIBC_BUILD_TYPE
+        EXECUTOR
         QEMU_MACHINE
         QEMU_CPU
         QEMU_PARAMS
+        FVP_MODEL
+        FVP_CONFIG
         BOOT_FLASH_ADDRESS
         BOOT_FLASH_SIZE
         FLASH_ADDRESS
@@ -1376,19 +1404,40 @@ function(add_library_variant target_arch)
 
     set(directory "${TARGET_LIBRARIES_DIR}${library_subdir}/${parent_dir_name}/${variant}")
     set(VARIANT_COMPILE_FLAGS "--target=${target_triple} ${VARIANT_COMPILE_FLAGS}")
-    get_test_executor_params(
-        "${target_triple}"
-        "${VARIANT_QEMU_MACHINE}"
-        "${VARIANT_QEMU_CPU}"
-        "${VARIANT_QEMU_PARAMS}"
-    )
-    set(
-        lit_test_executor
-        ${CMAKE_CURRENT_SOURCE_DIR}/test-support/lit-exec-qemu.py
-        ${test_executor_params}
-    )
+
+    if(VARIANT_EXECUTOR STREQUAL "fvp")
+      if(EXISTS "${FVP_INSTALL_DIR}")
+            get_fvp_params(
+              "${VARIANT_FVP_MODEL}"
+              "${VARIANT_FVP_CONFIG}"
+            )
+            set(
+                lit_test_executor
+                ${CMAKE_CURRENT_SOURCE_DIR}/test-support/lit-exec-fvp.py
+                ${test_executor_params}
+            )
+            set(have_executor TRUE)
+        else()
+            set(have_executor FALSE)
+        endif()
+    else()
+        get_qemu_params(
+            "${target_triple}"
+            "${VARIANT_QEMU_MACHINE}"
+            "${VARIANT_QEMU_CPU}"
+            "${VARIANT_QEMU_PARAMS}"
+        )
+        set(
+            lit_test_executor
+            ${CMAKE_CURRENT_SOURCE_DIR}/test-support/lit-exec-qemu.py
+            ${test_executor_params}
+        )
+        set(have_executor TRUE)
+    endif()
     list(JOIN lit_test_executor " " lit_test_executor)
-    if(NOT PREBUILT_TARGET_LIBRARIES)
+    if(NOT have_executor)
+        message("All library tests disabled for ${variant}, due to missing executor")
+    elseif(NOT PREBUILT_TARGET_LIBRARIES)
         add_libc(
             "${directory}"
             "${variant}"
@@ -1481,9 +1530,12 @@ function(add_library_variants_for_cpu target_arch)
         COMPILE_FLAGS
         MULTILIB_FLAGS
         PICOLIBC_BUILD_TYPE
+        EXECUTOR
         QEMU_MACHINE
         QEMU_CPU
         QEMU_PARAMS
+        FVP_MODEL
+        FVP_CONFIG
         BOOT_FLASH_ADDRESS
         BOOT_FLASH_SIZE
         FLASH_ADDRESS
@@ -1513,9 +1565,12 @@ function(add_library_variants_for_cpu target_arch)
             COMPILE_FLAGS "${VARIANT_COMPILE_FLAGS}"
             MULTILIB_FLAGS "${VARIANT_MULTILIB_FLAGS}"
             PICOLIBC_BUILD_TYPE "${VARIANT_PICOLIBC_BUILD_TYPE}"
+            EXECUTOR "${VARIANT_EXECUTOR}"
             QEMU_MACHINE "${VARIANT_QEMU_MACHINE}"
             QEMU_CPU "${VARIANT_QEMU_CPU}"
             QEMU_PARAMS "${VARIANT_QEMU_PARAMS}"
+            FVP_MODEL "${VARIANT_FVP_MODEL}"
+            FVP_CONFIG "${VARIANT_FVP_CONFIG}"
             BOOT_FLASH_ADDRESS "${VARIANT_BOOT_FLASH_ADDRESS}"
             BOOT_FLASH_SIZE "${VARIANT_BOOT_FLASH_SIZE}"
             FLASH_ADDRESS "${VARIANT_FLASH_ADDRESS}"
@@ -1898,20 +1953,17 @@ add_nonexistent_library_variant(
     MULTILIB_FLAGS "--target=thumbv8.1m.main-unknown-none-eabi -march=thumbv8.1m.main+mve"
     ERROR_MESSAGE "No library available for MVE with soft-float ABI. Try -mfloat-abi=hard."
 )
-# FIXME: qemu currently has no support for PACBTI-M, so the branch protection
-# variants below can't be fully tested in runtime. Since PACBTI-M instructions
-# are NOP-compatible we can use the cortex-m55 CPU for now, but these should be
-# updated to use a PACBTI-M enabled CPU once this is available.
 add_library_variants_for_cpu(
     armv8.1m.main
     SUFFIX soft_nofp_nomve_pacret_bti
     COMPILE_FLAGS "-mfloat-abi=soft -march=armv8.1m.main+nomve+pacbti -mfpu=none -mbranch-protection=pac-ret+bti"
     MULTILIB_FLAGS "--target=thumbv8.1m.main-unknown-none-eabi -mfpu=none -mbranch-protection=pac-ret+bti"
     PICOLIBC_BUILD_TYPE "release"
-    QEMU_MACHINE "mps3-an547"
-    QEMU_CPU "cortex-m55"
-    BOOT_FLASH_ADDRESS 0x00000000
-    BOOT_FLASH_SIZE 512K
+    EXECUTOR fvp
+    FVP_MODEL corstone-310
+    FVP_CONFIG "cortex-m85 m-pacbti m-nofp mve-none"
+    BOOT_FLASH_ADDRESS 0x01000000
+    BOOT_FLASH_SIZE 2M
     FLASH_ADDRESS 0x60000000
     FLASH_SIZE 0x1000000
     RAM_ADDRESS 0x61000000
@@ -1924,10 +1976,11 @@ add_library_variants_for_cpu(
     COMPILE_FLAGS "-mfloat-abi=hard -march=armv8.1m.main+nomve+pacbti -mfpu=fp-armv8-fullfp16-sp-d16 -mbranch-protection=pac-ret+bti"
     MULTILIB_FLAGS "--target=thumbv8.1m.main-unknown-none-eabihf -march=thumbv8.1m.main+fp16 -mfpu=fp-armv8-fullfp16-sp-d16 -mbranch-protection=pac-ret+bti"
     PICOLIBC_BUILD_TYPE "release"
-    QEMU_MACHINE "mps3-an547"
-    QEMU_CPU "cortex-m55"
-    BOOT_FLASH_ADDRESS 0x00000000
-    BOOT_FLASH_SIZE 512K
+    EXECUTOR fvp
+    FVP_MODEL corstone-310
+    FVP_CONFIG "cortex-m85 m-pacbti m-fp mve-none"
+    BOOT_FLASH_ADDRESS 0x01000000
+    BOOT_FLASH_SIZE 2M
     FLASH_ADDRESS 0x60000000
     FLASH_SIZE 0x1000000
     RAM_ADDRESS 0x61000000
@@ -1940,10 +1993,11 @@ add_library_variants_for_cpu(
     COMPILE_FLAGS "-mfloat-abi=hard -march=armv8.1m.main+nomve+pacbti -mfpu=fp-armv8-fullfp16-d16 -mbranch-protection=pac-ret+bti"
     MULTILIB_FLAGS "--target=thumbv8.1m.main-unknown-none-eabihf -march=thumbv8.1m.main+fp16 -mfpu=fp-armv8-fullfp16-d16 -mbranch-protection=pac-ret+bti"
     PICOLIBC_BUILD_TYPE "release"
-    QEMU_MACHINE "mps3-an547"
-    QEMU_CPU "cortex-m55"
-    BOOT_FLASH_ADDRESS 0x00000000
-    BOOT_FLASH_SIZE 512K
+    EXECUTOR fvp
+    FVP_MODEL corstone-310
+    FVP_CONFIG "cortex-m85 m-pacbti m-fp mve-none"
+    BOOT_FLASH_ADDRESS 0x01000000
+    BOOT_FLASH_SIZE 2M
     FLASH_ADDRESS 0x60000000
     FLASH_SIZE 0x1000000
     RAM_ADDRESS 0x61000000
@@ -1956,10 +2010,11 @@ add_library_variants_for_cpu(
     COMPILE_FLAGS "-mfloat-abi=hard -march=armv8.1m.main+mve+pacbti -mfpu=none -mbranch-protection=pac-ret+bti"
     MULTILIB_FLAGS "--target=thumbv8.1m.main-unknown-none-eabihf -march=thumbv8.1m.main+mve -mfpu=none -mbranch-protection=pac-ret+bti"
     PICOLIBC_BUILD_TYPE "release"
-    QEMU_MACHINE "mps3-an547"
-    QEMU_CPU "cortex-m55"
-    BOOT_FLASH_ADDRESS 0x00000000
-    BOOT_FLASH_SIZE 512K
+    EXECUTOR fvp
+    FVP_MODEL corstone-310
+    FVP_CONFIG "cortex-m85 m-pacbti m-nofp mve-int"
+    BOOT_FLASH_ADDRESS 0x01000000
+    BOOT_FLASH_SIZE 2M
     FLASH_ADDRESS 0x60000000
     FLASH_SIZE 0x1000000
     RAM_ADDRESS 0x61000000

README.md

@@ -60,6 +60,10 @@ Content of this repository is licensed under Apache-2.0. See
 The resulting binaries are covered under their respective open source licenses,
 see component links above.
 
+Testing for some targets uses the freely-available but not open-source Arm FVP
+models, which have their own licenses. These are not used by default, see
+[Building from source](docs/building-from-source.md) for details.
+
 ## Host platforms
 
 LLVM Embedded Toolchain for Arm is built and tested on Ubuntu 18.04 LTS.

docs/building-from-source.md

@@ -36,6 +36,26 @@ $ brew install llvm python3 git make ninja qemu cmake
 $ pip install meson
 ```
 
+Some recent targets are not supported by QEMU, for these the Arm FVP models are
+used instead. These models are available free-of-change but are not
+open-source, and come with their own licenses.
+
+These models can be downloaded and installed (into the source tree) with the
+`fvp/get_fvps.sh` script. This is currently only available for Linux. By
+default, `get_fvps.sh` will run the installers for packages which have them,
+which will prompt you to agree to their licenses. Some of the packages do not
+have installers, instead they place their license file into the
+`fvp/license_terms` directory, which you should read before continuing.
+
+For non-interactive use (for example in CI systems), `get_fvps.sh` can be run
+with the `--non-interactive` option, which causes it to implcitly accept all of
+the EULAs. If you have previously downloaded and installed the FVPs outside of
+the source tree, you can set the `-DFVP_INSTALL_DIR=...` cmake option to set
+the path to them.
+
+If the FVPs are not installed, tests which need them will be skipped, but QEMU
+tests will still be run, and all library variants will still be built.
+
 ## Customizing
 
 To build additional library variants, edit the `CMakeLists.txt` by adding

fvp/config/cortex-m85.cfg

@@ -0,0 +1,14 @@
+# SPDX-FileCopyrightText: Copyright 2024 Arm Limited and/or its affiliates <[email protected]>
+
+# Disable GUI visualisation.
+mps3_board.visualisation.disable-visualisation=1
+
+# Silence output about telnet ports.
+# Yes, the terminals are numbered 0, 1, 2 and 5
+mps3_board.telnetterminal0.quiet=1
+mps3_board.telnetterminal1.quiet=1
+mps3_board.telnetterminal2.quiet=1
+mps3_board.telnetterminal5.quiet=1
+
+# Enable semihosting
+cpu0.semihosting-enable=1

fvp/config/m-fp.cfg

@@ -0,0 +1,6 @@
+# SPDX-FileCopyrightText: Copyright 2024 Arm Limited and/or its affiliates <[email protected]>
+
+# Enable M-profile scalar FPU. This includes the double-precision extension, I
+# don't see a parameter to disable that in the Corstone-310 FVP, probably
+# because Cortex-M85 can't be configured with an SP-only FPU.
+cpu0.FPU=1

fvp/config/m-nofp.cfg

@@ -0,0 +1,4 @@
+# SPDX-FileCopyrightText: Copyright 2024 Arm Limited and/or its affiliates <[email protected]>
+
+# Disable M-profile scalar FPU
+cpu0.FPU=0

fvp/config/m-pacbti.cfg

@@ -0,0 +1,5 @@
+# SPDX-FileCopyrightText: Copyright 2024 Arm Limited and/or its affiliates <[email protected]>
+
+# Enable M-profile PAC and BTI
+cpu0.CFGPACBTI=1
+cpu0.ID_ISAR5.PACBTI=1

fvp/config/mve-fp.cfg

@@ -0,0 +1,4 @@
+# SPDX-FileCopyrightText: Copyright 2024 Arm Limited and/or its affiliates <[email protected]>
+
+# Enable integer and floating-point MVE
+cpu0.MVE=2

fvp/config/mve-int.cfg

@@ -0,0 +1,4 @@
+# SPDX-FileCopyrightText: Copyright 2024 Arm Limited and/or its affiliates <[email protected]>
+
+# Enable integer-only MVE
+cpu0.MVE=1