kprobes: rethook,ARM,arm64: Replace kretprobe trampoline with rethook

.github/actions/vmtest/action.yml

@@ -0,0 +1,35 @@
+name: 'vmtest'
+description: 'Build + run vmtest'
+inputs:
+  arch:
+    description: 'what arch to test'
+    required: true
+    default: 'x86_64'
+runs:
+  using: "composite"
+  steps:
+    # 1. Setup environment
+    - name: Setup build environment
+      uses: libbpf/ci/setup-build-env@master
+    # 2. Build
+    - name: Build kernel image
+      shell: bash
+      run: ${GITHUB_ACTION_PATH}/build.sh ${{ inputs.arch }}
+    - name: Build selftests
+      shell: bash
+      run: ${GITHUB_ACTION_PATH}/build_selftests.sh
+      env:
+        VMLINUX_BTF: ${{ github.workspace }}/vmlinux
+    # 3. Test
+    - name: Prepare rootfs
+      uses: libbpf/ci/prepare-rootfs@master
+      with:
+        project-name: 'libbpf'
+        arch: ${{ inputs.arch }}
+        kernel-root: '.'
+    - name: Run selftests
+      uses: libbpf/ci/run-qemu@master
+      with:
+        arch: ${{ inputs.arch}}
+        img: '/tmp/root.img'
+        vmlinuz: '${{ github.workspace }}/vmlinuz'

.github/actions/vmtest/build.sh

@@ -0,0 +1,17 @@
+#!/bin/bash
+
+set -euo pipefail
+
+ARCH="$1"
+
+THISDIR="$(cd $(dirname $0) && pwd)"
+
+source "${THISDIR}"/helpers.sh
+
+travis_fold start build_kernel "Building kernel"
+
+cp ${GITHUB_WORKSPACE}/travis-ci/vmtest/configs/config-latest.${ARCH} .config
+
+make -j $((4*$(nproc))) olddefconfig all > /dev/null
+
+travis_fold end build_kernel

.github/actions/vmtest/build_selftests.sh

@@ -0,0 +1,42 @@
+#!/bin/bash
+
+set -euo pipefail
+
+THISDIR="$(cd $(dirname $0) && pwd)"
+
+source "${THISDIR}"/helpers.sh
+
+travis_fold start prepare_selftests "Building selftests"
+
+LLVM_VER=15
+LIBBPF_PATH="${REPO_ROOT}"
+
+PREPARE_SELFTESTS_SCRIPT=${THISDIR}/prepare_selftests-${KERNEL}.sh
+if [ -f "${PREPARE_SELFTESTS_SCRIPT}" ]; then
+	(cd "${REPO_ROOT}/${REPO_PATH}/tools/testing/selftests/bpf" && ${PREPARE_SELFTESTS_SCRIPT})
+fi
+
+if [[ "${KERNEL}" = 'LATEST' ]]; then
+	VMLINUX_H=
+else
+	VMLINUX_H=${THISDIR}/vmlinux.h
+fi
+
+cd ${REPO_ROOT}/${REPO_PATH}
+make \
+	CLANG=clang-${LLVM_VER} \
+	LLC=llc-${LLVM_VER} \
+	LLVM_STRIP=llvm-strip-${LLVM_VER} \
+	VMLINUX_BTF="${VMLINUX_BTF}" \
+	VMLINUX_H="${VMLINUX_H}" \
+	-C "${REPO_ROOT}/${REPO_PATH}/tools/testing/selftests/bpf" \
+	-j $((4*$(nproc))) > /dev/null
+cd -
+mkdir "${LIBBPF_PATH}"/selftests
+cp -R "${REPO_ROOT}/${REPO_PATH}/tools/testing/selftests/bpf" \
+	"${LIBBPF_PATH}"/selftests
+cd "${LIBBPF_PATH}"
+rm selftests/bpf/.gitignore
+git add selftests
+
+travis_fold end prepare_selftests

.github/actions/vmtest/helpers.sh

@@ -0,0 +1,44 @@
+# $1 - start or end
+# $2 - fold identifier, no spaces
+# $3 - fold section description
+travis_fold() {
+  local YELLOW='\033[1;33m'
+  local NOCOLOR='\033[0m'
+  if [ -z ${GITHUB_WORKFLOW+x} ]; then
+    echo travis_fold:$1:$2
+    if [ ! -z "${3:-}" ]; then
+      echo -e "${YELLOW}$3${NOCOLOR}"
+    fi
+    echo
+  else
+    if [ $1 = "start" ]; then
+      line="::group::$2"
+      if [ ! -z "${3:-}" ]; then
+        line="$line - ${YELLOW}$3${NOCOLOR}"
+      fi
+    else
+      line="::endgroup::"
+    fi
+    echo -e "$line"
+  fi
+}
+
+__print() {
+  local TITLE=""
+  if [[ -n $2 ]]; then
+      TITLE=" title=$2"
+  fi
+  echo "::$1${TITLE}::$3"
+}
+
+# $1 - title
+# $2 - message
+print_error() {
+  __print error $1 $2
+}
+
+# $1 - title
+# $2 - message
+print_notice() {
+  __print notice $1 $2
+}

.github/workflows/test.yml

@@ -0,0 +1,50 @@
+name: bpf-ci
+
+on:
+  pull_request:
+
+concurrency: 
+  group: ci-test-${{ github.head_ref }}
+  cancel-in-progress: true
+
+jobs:
+  VM_Test:
+    runs-on: ${{ matrix.runs_on }}
+    name: Kernel ${{ matrix.kernel }} on ${{ matrix.runs_on }} + selftests
+    timeout-minutes: 100
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - kernel: 'LATEST'
+            runs_on: ubuntu-latest
+            arch: 'x86_64'
+          - kernel: 'LATEST'
+            runs_on: z15
+            arch: 's390x'
+    env:
+      AUTHOR_EMAIL: "$(git log -1 --pretty=\"%aE\")"
+      KERNEL: LATEST
+      REPO_ROOT: ${{ github.workspace }}
+      REPO_PATH: ""
+    steps:
+      - uses: actions/checkout@v2
+      - if: ${{ github.repository != 'kernel-patches/bpf' && github.repository != 'kernel-patches/bpf-rc' }}
+        name: Download bpf-next tree
+        uses: libbpf/ci/get-linux-source@master
+        with:
+          dest: '.kernel'
+      - if: ${{ github.repository != 'kernel-patches/bpf' && github.repository != 'kernel-patches/bpf-rc' }}
+        name: Move linux source in place
+        shell: bash
+        run: |
+          rm -rf .kernel/.git
+          cp -rf .kernel/. .
+          rm -rf .kernel
+      - uses: libbpf/ci/patch-kernel@master
+        with:
+          patches-root: '${{ github.workspace }}/travis-ci/diffs'
+          repo-root: '${{ github.workspace }}'
+      - uses: ./.github/actions/vmtest
+        with:
+          arch: ${{ matrix.arch }}

README

@@ -1,18 +0,0 @@
-Linux kernel
-============
-
-There are several guides for kernel developers and users. These guides can
-be rendered in a number of formats, like HTML and PDF. Please read
-Documentation/admin-guide/README.rst first.
-
-In order to build the documentation, use ``make htmldocs`` or
-``make pdfdocs``.  The formatted documentation can also be read online at:
-
-    https://www.kernel.org/doc/html/latest/
-
-There are various text files in the Documentation/ subdirectory,
-several of them using the Restructured Text markup notation.
-
-Please read the Documentation/process/changes.rst file, as it contains the
-requirements for building and running the kernel, and information about
-the problems which may result by upgrading your kernel.

arch/arm/Kconfig

@@ -110,6 +110,7 @@ config ARM
 	select HAVE_MOD_ARCH_SPECIFIC
 	select HAVE_NMI
 	select HAVE_OPTPROBES if !THUMB2_KERNEL
+	select HAVE_RETHOOK
 	select HAVE_PERF_EVENTS
 	select HAVE_PERF_REGS
 	select HAVE_PERF_USER_STACK_DUMP

arch/arm/include/asm/stacktrace.h

@@ -17,7 +17,8 @@ struct stackframe {
 
 	/* address of the LR value on the stack */
 	unsigned long *lr_addr;
-#ifdef CONFIG_KRETPROBES
+
+#if defined(CONFIG_RETHOOK)
 	struct llist_node *kr_cur;
 	struct task_struct *tsk;
 #endif
@@ -30,7 +31,7 @@ void arm_get_current_stackframe(struct pt_regs *regs, struct stackframe *frame)
 		frame->sp = regs->ARM_sp;
 		frame->lr = regs->ARM_lr;
 		frame->pc = regs->ARM_pc;
-#ifdef CONFIG_KRETPROBES
+#if defined(CONFIG_RETHOOK)
 		frame->kr_cur = NULL;
 		frame->tsk = current;
 #endif

arch/arm/kernel/stacktrace.c

@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0-only
 #include <linux/export.h>
 #include <linux/kprobes.h>
+#include <linux/rethook.h>
 #include <linux/sched.h>
 #include <linux/sched/debug.h>
 #include <linux/stacktrace.h>
@@ -66,10 +67,10 @@ int notrace unwind_frame(struct stackframe *frame)
 	frame->sp = *(unsigned long *)(fp - 8);
 	frame->pc = *(unsigned long *)(fp - 4);
 #endif
-#ifdef CONFIG_KRETPROBES
-	if (is_kretprobe_trampoline(frame->pc))
-		frame->pc = kretprobe_find_ret_addr(frame->tsk,
-					(void *)frame->fp, &frame->kr_cur);
+#ifdef CONFIG_RETHOOK
+	if (is_rethook_trampoline(frame->pc))
+		frame->pc = rethook_find_ret_addr(frame->tsk, frame->fp,
+						  &frame->kr_cur);
 #endif
 
 	return 0;
@@ -163,7 +164,7 @@ static noinline void __save_stack_trace(struct task_struct *tsk,
 here:
 		frame.pc = (unsigned long)&&here;
 	}
-#ifdef CONFIG_KRETPROBES
+#ifdef CONFIG_RETHOOK
 	frame.kr_cur = NULL;
 	frame.tsk = tsk;
 #endif
@@ -184,7 +185,7 @@ void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
 	frame.sp = regs->ARM_sp;
 	frame.lr = regs->ARM_lr;
 	frame.pc = regs->ARM_pc;
-#ifdef CONFIG_KRETPROBES
+#ifdef CONFIG_RETHOOK
 	frame.kr_cur = NULL;
 	frame.tsk = current;
 #endif

arch/arm/kernel/unwind.c

@@ -404,6 +404,7 @@ int unwind_frame(struct stackframe *frame)
 	ctrl.vrs[SP] = frame->sp;
 	ctrl.vrs[LR] = frame->lr;
 	ctrl.vrs[PC] = 0;
+	ctrl.lr_addr = NULL;
 
 	if (idx->insn == 1)
 		/* can't unwind */

arch/arm/probes/Makefile

@@ -6,3 +6,4 @@ obj-$(CONFIG_KPROBES)		+= decode-thumb.o
 else
 obj-$(CONFIG_KPROBES)		+= decode-arm.o
 endif
+obj-$(CONFIG_RETHOOK)		+= rethook.o

arch/arm/probes/kprobes/core.c

@@ -365,68 +365,6 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
 	return NOTIFY_DONE;
 }
 
-/*
- * When a retprobed function returns, trampoline_handler() is called,
- * calling the kretprobe's handler. We construct a struct pt_regs to
- * give a view of registers r0-r11, sp, lr, and pc to the user
- * return-handler. This is not a complete pt_regs structure, but that
- * should be enough for stacktrace from the return handler with or
- * without pt_regs.
- */
-void __naked __kprobes __kretprobe_trampoline(void)
-{
-	__asm__ __volatile__ (
-#ifdef CONFIG_FRAME_POINTER
-		"ldr	lr, =__kretprobe_trampoline	\n\t"
-	/* __kretprobe_trampoline makes a framepointer on pt_regs. */
-#ifdef CONFIG_CC_IS_CLANG
-		"stmdb	sp, {sp, lr, pc}	\n\t"
-		"sub	sp, sp, #12		\n\t"
-		/* In clang case, pt_regs->ip = lr. */
-		"stmdb	sp!, {r0 - r11, lr}	\n\t"
-		/* fp points regs->r11 (fp) */
-		"add	fp, sp,	#44		\n\t"
-#else /* !CONFIG_CC_IS_CLANG */
-		/* In gcc case, pt_regs->ip = fp. */
-		"stmdb	sp, {fp, sp, lr, pc}	\n\t"
-		"sub	sp, sp, #16		\n\t"
-		"stmdb	sp!, {r0 - r11}		\n\t"
-		/* fp points regs->r15 (pc) */
-		"add	fp, sp, #60		\n\t"
-#endif /* CONFIG_CC_IS_CLANG */
-#else /* !CONFIG_FRAME_POINTER */
-		"sub	sp, sp, #16		\n\t"
-		"stmdb	sp!, {r0 - r11}		\n\t"
-#endif /* CONFIG_FRAME_POINTER */
-		"mov	r0, sp			\n\t"
-		"bl	trampoline_handler	\n\t"
-		"mov	lr, r0			\n\t"
-		"ldmia	sp!, {r0 - r11}		\n\t"
-		"add	sp, sp, #16		\n\t"
-#ifdef CONFIG_THUMB2_KERNEL
-		"bx	lr			\n\t"
-#else
-		"mov	pc, lr			\n\t"
-#endif
-		: : : "memory");
-}
-
-/* Called from __kretprobe_trampoline */
-static __used __kprobes void *trampoline_handler(struct pt_regs *regs)
-{
-	return (void *)kretprobe_trampoline_handler(regs, (void *)regs->ARM_fp);
-}
-
-void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
-				      struct pt_regs *regs)
-{
-	ri->ret_addr = (kprobe_opcode_t *)regs->ARM_lr;
-	ri->fp = (void *)regs->ARM_fp;
-
-	/* Replace the return addr with trampoline addr. */
-	regs->ARM_lr = (unsigned long)&__kretprobe_trampoline;
-}
-
 int __kprobes arch_trampoline_kprobe(struct kprobe *p)
 {
 	return 0;