[github] Merge pull request #380 from arichardson/add-clang-ci

Allow building RISCV64 and x86_64 with clang and add a Clang CI job

9 files changed, 126 insertions, 27 deletions

diff --git a/.github/workflows/github-ci-clang.yml b/.github/workflows/github-ci-clang.yml
new file mode 100644
index 00000000..19dc5612
--- /dev/null
+++ b/.github/workflows/github-ci-clang.yml
@@ -0,0 +1,70 @@
+name: LK CI (Clang)
+
+# Brute force build a bunch of variants of LK in parallel jobs.
+
+on: [ push, pull_request ]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        toolchain-ver: [13, 14, 15]
+        debug: [2]
+        project:
+          # Note: Clang toolchains do not ship with a compiler-rt (libgcc) for
+          # all targets, so we have to restrict this build matrix to targets
+          # that build without requiring these functions (i.e. 64-bit targets,
+          # since 32-bit ones require functions such as __divdi3).
+          - pc-x86-64-test
+          - qemu-virt-arm64-test
+          - qemu-virt-riscv64-test
+          - qemu-virt-riscv64-supervisor-test
+    env:
+      PROJECT: ${{ matrix.project }}
+      TOOLCHAIN_VER: ${{ matrix.toolchain-ver }}
+      DEBUG: ${{ matrix.debug }}
+      UBSAN: 0  # UBSan runtimes for baremetal are not part of the toolchain
+    steps:
+    - name: banner
+      shell: bash
+      run: |
+        printf "Building with %d processors\n" "$(nproc)"
+        grep -oP '(?<=model name\t: ).*' /proc/cpuinfo|head -n1
+        echo PROJECT = $PROJECT
+        echo TOOLCHAIN_VER = $TOOLCHAIN_VER
+        echo DEBUG = $DEBUG
+        echo UBSAN = $UBSAN
+
+    - name: checkout
+      uses: actions/checkout@v3
+
+    # Install LLVM and set up the required environment variables
+    - name: compute toolchain
+      shell: bash
+      run: |
+        sudo apt install clang-${{ matrix.toolchain-ver }} lld-${{ matrix.toolchain-ver }}
+        GCC_TOOLCHAIN_PREFIX=$(make list-toolchain | grep TOOLCHAIN_PREFIX | tail -1 | cut -d ' ' -f 3)
+        # Map the GCC toolchain prefix to a clang --target argument:
+        CLANG_TRIPLE=$(echo "${GCC_TOOLCHAIN_PREFIX}" | sed 's/-elf-/-unknown-elf/g')
+        LLVM_BINDIR=/usr/lib/llvm-${{ matrix.toolchain-ver }}/bin
+        echo "CC=${LLVM_BINDIR}/clang --target=${CLANG_TRIPLE}" >> $GITHUB_ENV
+        echo "LD=${LLVM_BINDIR}/ld.lld" >> $GITHUB_ENV
+        echo "OBJDUMP=${LLVM_BINDIR}/llvm-objdump" >> $GITHUB_ENV
+        echo "OBJCOPY=${LLVM_BINDIR}/llvm-objcopy" >> $GITHUB_ENV
+        echo "CPPFILT=${LLVM_BINDIR}/llvm-cxxfilt" >> $GITHUB_ENV
+        echo "SIZE=${LLVM_BINDIR}/llvm-size" >> $GITHUB_ENV
+        echo "NM=${LLVM_BINDIR}/llvm-nm" >> $GITHUB_ENV
+        echo "STRIP=${LLVM_BINDIR}/llvm-strip" >> $GITHUB_ENV
+        echo "TOOLCHAIN_PREFIX=/invalid/prefix/should/not/be/used" >> $GITHUB_ENV
+        echo "LIBGCC=" >> $GITHUB_ENV
+        cat "$GITHUB_ENV"
+
+    # build it
+    - name: build
+      shell: bash
+      run: |
+        make -j $(nproc)
+
+# vim: ts=2 sw=2 expandtab
diff --git a/arch/riscv/include/arch/riscv.h b/arch/riscv/include/arch/riscv.h
index 340284d4..ac265f0d 100644
--- a/arch/riscv/include/arch/riscv.h
+++ b/arch/riscv/include/arch/riscv.h
@@ -19,9 +19,11 @@
 #if RISCV_M_MODE
 # define RISCV_XMODE_OFFSET     (RISCV_MACH_OFFSET)
 # define RISCV_XRET             mret
+# define RISCV_MODE_PREFIX      m
 #elif RISCV_S_MODE
 # define RISCV_XMODE_OFFSET     (RISCV_SUPER_OFFSET)
 # define RISCV_XRET             sret
+# define RISCV_MODE_PREFIX      s
 #else
 # error Unrecognized RISC-V privilege level selected
 #endif
@@ -36,14 +38,14 @@
 #define RISCV_CSR_TIMEH     (0xc81)
 #define RISCV_CSR_INSRETH   (0xc82)
 
-#define RISCV_CSR_XSTATUS   (0x000 | RISCV_CSR_XMODE_BITS)
-#define RISCV_CSR_XIE       (0x004 | RISCV_CSR_XMODE_BITS)
-#define RISCV_CSR_XTVEC     (0x005 | RISCV_CSR_XMODE_BITS)
-#define RISCV_CSR_XSCRATCH  (0x040 | RISCV_CSR_XMODE_BITS)
-#define RISCV_CSR_XEPC      (0x041 | RISCV_CSR_XMODE_BITS)
-#define RISCV_CSR_XCAUSE    (0x042 | RISCV_CSR_XMODE_BITS)
-#define RISCV_CSR_XTVAL     (0x043 | RISCV_CSR_XMODE_BITS)
-#define RISCV_CSR_XIP       (0x044 | RISCV_CSR_XMODE_BITS)
+#define RISCV_CSR_XSTATUS   __CONCAT(RISCV_MODE_PREFIX, status)
+#define RISCV_CSR_XIE       __CONCAT(RISCV_MODE_PREFIX, ie)
+#define RISCV_CSR_XTVEC     __CONCAT(RISCV_MODE_PREFIX, tvec)
+#define RISCV_CSR_XSCRATCH  __CONCAT(RISCV_MODE_PREFIX, scratch)
+#define RISCV_CSR_XEPC      __CONCAT(RISCV_MODE_PREFIX, epc)
+#define RISCV_CSR_XCAUSE    __CONCAT(RISCV_MODE_PREFIX, cause)
+#define RISCV_CSR_XTVAL     __CONCAT(RISCV_MODE_PREFIX, tval)
+#define RISCV_CSR_XIP       __CONCAT(RISCV_MODE_PREFIX, ip)
 
 #if RISCV_M_MODE // Machine-mode only CSRs
 #define RISCV_CSR_MCYCLE    (0xb00)
@@ -55,7 +57,7 @@
 #endif // RISCV_M_MODE
 
 #if RISCV_S_MODE // Supervisor-mode only CSRs
-#define RISCV_CSR_SATP      (0x180)
+#define RISCV_CSR_SATP      satp
 #endif
 
 #define RISCV_CSR_XSTATUS_IE    (1ul << (RISCV_XMODE_OFFSET + 0))
diff --git a/arch/x86/32/exceptions.S b/arch/x86/32/exceptions.S
index 8ca8771b..98ac81f1 100644
--- a/arch/x86/32/exceptions.S
+++ b/arch/x86/32/exceptions.S
@@ -21,8 +21,7 @@ _isr:
 .set i, 0
 .rept NUM_INT
 
-.set isr_stub_start, .
-
+100:  /* unnamed label for start of isr stub */
 .if i == 8 || (i >= 10 && i <= 14) || i == 17
     nop                     /* error code pushed by exception */
     nop                     /* 2 nops are the same length as push byte */
@@ -34,12 +33,12 @@ _isr:
     jmp interrupt_common
 .endif
 
-/* figure out the length of a single isr stub (usually 6 or 9 bytes) */
-.set isr_stub_len, . - isr_stub_start
-
 .set i, i + 1
 .endr
 
+/* figure out the length of a single isr stub (usually 6 or 9 bytes) */
+.set isr_stub_len, . - 100b
+
 /* annoying, but force AS to use the same (longer) encoding of jmp for all of the stubs */
 .fill 256
 
diff --git a/arch/x86/64/exceptions.S b/arch/x86/64/exceptions.S
index e66c53ce..86a54827 100644
--- a/arch/x86/64/exceptions.S
+++ b/arch/x86/64/exceptions.S
@@ -26,7 +26,7 @@ _isr:
 .set i, 0
 .rept NUM_INT
 
-.set isr_stub_start, .
+100:  /* unnamed label for start of isr stub */
 
 .if i == 8 || (i >= 10 && i <= 14) || i == 17
 .align 16
@@ -43,12 +43,12 @@ _isr:
 .align 16
 .endif
 
-/* figure out the length of a single isr stub (usually 6 or 9 bytes) */
-.set isr_stub_len, . - isr_stub_start
-
 .set i, i + 1
 .endr
 
+/* figure out the length of a single isr stub (usually 6 or 9 bytes) */
+.set isr_stub_len, . - 100b
+
 /* annoying, but force AS to use the same (longer) encoding of jmp for all of the stubs */
 .fill 256
 
diff --git a/arch/x86/64/start.S b/arch/x86/64/start.S
index b11e8bca..7637525a 100644
--- a/arch/x86/64/start.S
+++ b/arch/x86/64/start.S
@@ -74,7 +74,7 @@ real_start:
     /* far jump to load the CS from our GDT */
     pushl $CODE_SELECTOR
     pushl $PHYS(.Lfarjump)
-    retf
+    lret
 
 .Lfarjump:
 
@@ -185,7 +185,7 @@ paging_setup:
     /* Use a far jump to get into 64bit mode */
     pushl $CODE_64_SELECTOR
     pushl $PHYS(farjump64)
-    retf
+    lret
 
 .align 8
 .code64
diff --git a/engine.mk b/engine.mk
index 3a92d672..e56d1b23 100644
--- a/engine.mk
+++ b/engine.mk
@@ -66,6 +66,9 @@ GLOBAL_COMPILEFLAGS := -g -include $(CONFIGHEADER)
 GLOBAL_COMPILEFLAGS += -Wextra -Wall -Werror=return-type -Wshadow -Wdouble-promotion
 GLOBAL_COMPILEFLAGS += -Wno-multichar -Wno-unused-parameter -Wno-unused-function -Wno-unused-label
 GLOBAL_COMPILEFLAGS += -fno-common
+# Build with -ffreestanding since we are building an OS kernel and cannot
+# rely on all hosted environment functionality being present.
+GLOBAL_COMPILEFLAGS += -ffreestanding
 GLOBAL_CFLAGS := --std=gnu11 -Werror-implicit-function-declaration -Wstrict-prototypes -Wwrite-strings
 GLOBAL_CPPFLAGS := --std=c++14 -fno-exceptions -fno-rtti -fno-threadsafe-statics
 GLOBAL_ASMFLAGS := -DASSEMBLY
@@ -192,6 +195,15 @@ SIZE ?= $(TOOLCHAIN_PREFIX)size
 NM ?= $(TOOLCHAIN_PREFIX)nm
 STRIP ?= $(TOOLCHAIN_PREFIX)strip
 
+# Detect whether we are using ld.lld. If we don't detect ld.lld, we assume
+# it's ld.bfd. This check can be refined in the future if we need to handle
+# more cases (e.g. ld.gold).
+LINKER_TYPE := $(shell $(LD) -v 2>&1 | grep -q "LLD" && echo lld || echo bfd)
+$(info LINKER_TYPE=$(LINKER_TYPE))
+# Detect whether we are compiling with GCC or Clang
+COMPILER_TYPE := $(shell $(CC) -v 2>&1 | grep -q "clang version" && echo clang || echo gcc)
+$(info COMPILER_TYPE=$(COMPILER_TYPE))
+
 # Now that CC is defined we can check if warning flags are supported and add
 # them to GLOBAL_COMPILEFLAGS if they are.
 ifeq ($(call is_warning_flag_supported,-Wnonnull-compare),yes)
@@ -207,6 +219,26 @@ ARCH_COMPILEFLAGS += -Wno-asm-operand-widths
 endif
 endif
 
+ifeq ($(ARCH),riscv)
+# ld.lld does not support linker relaxations yet.
+# TODO: This is no longer true as of LLVM 15, so should add a version check
+ifeq ($(LINKER_TYPE),lld)
+ARCH_COMPILEFLAGS += -mno-relax
+# Work around out-of-range undef-weak relocations when building with clang and
+# linking with ld.lld. This is not a problem with ld.bfd since ld.bfd rewrites
+# the instructions to avoid the out-of-range PC-relative relocation
+# See https://github.com/riscv-non-isa/riscv-elf-psabi-doc/issues/126 for more
+# details. For now, the simplest workaround is to build with -fpie when using
+# a version of clang that does not include https://reviews.llvm.org/D107280.
+# TODO: Add a clang 17 version check now that the review has been merged.
+ifeq ($(COMPILER_TYPE),clang)
+# We also add the -fdirect-access-external-data flag is added to avoid the
+# majority of the performance overhead caused by -fPIE.
+ARCH_COMPILEFLAGS += -fPIE -fdirect-access-external-data
+endif
+endif
+endif
+
 $(info PROJECT = $(PROJECT))
 $(info PLATFORM = $(PLATFORM))
 $(info TARGET = $(TARGET))
diff --git a/external/platform/pico/rp2_common/pico_platform/include/pico/platform.h b/external/platform/pico/rp2_common/pico_platform/include/pico/platform.h
index 2ed5e212..d0771e1e 100644
--- a/external/platform/pico/rp2_common/pico_platform/include/pico/platform.h
+++ b/external/platform/pico/rp2_common/pico_platform/include/pico/platform.h
@@ -7,7 +7,6 @@
 #ifndef _PICO_PLATFORM_H_
 #define _PICO_PLATFORM_H_
 
-#include <sys/cdefs.h>
 #include "pico/types.h"
 #include "hardware/platform_defs.h"
 
diff --git a/platform/rp20xx/include/sys/cdefs.h b/platform/rp20xx/include/sys/cdefs.h
deleted file mode 100644
index 9fc7e4f4..00000000
--- a/platform/rp20xx/include/sys/cdefs.h
+++ /dev/null
@@ -1,6 +0,0 @@
-#pragma once
-
-#ifndef __CONCAT
-#define __CONCAT1(x,y) x ## y
-#define __CONCAT(x,y) __CONCAT1(x,y)
-#endif
diff --git a/top/include/lk/compiler.h b/top/include/lk/compiler.h
index 45b1dc81..04236826 100644
--- a/top/include/lk/compiler.h
+++ b/top/include/lk/compiler.h
@@ -11,6 +11,9 @@
 
 #pragma once
 
+#define __CONCAT1(x, y) x ## y
+#define __CONCAT(x, y) __CONCAT1(x, y)
+
 #ifndef __ASSEMBLY__
 
 #if __GNUC__ || __clang__