x86/kprobes: Fix crash when probing CS CALL instructionsgrafted

When using eBPF to probe CS CALL instructions within a function,
a crash can be triggered.

The eBPF tool probes offset 257 of the __hrtimer_run_queues()
function:

<__hrtimer_run_queues+249>:  nopl   0x0(%rax,%rax,1)
<__hrtimer_run_queues+254>:  mov    %r14,%rdi
<__hrtimer_run_queues+257>:  cs call <__x86_indirect_thunk_r12>
<__hrtimer_run_queues+263>:  mov    %eax,%r12d
<__hrtimer_run_queues+266>:  xchg   %ax,%ax
<__hrtimer_run_queues+268>:  mov    %r13,%rdi

Which triggers this crash:

  BUG: unable to handle page fault for address: 00000000000f41c9
  #PF: supervisor write access in kernel mode
  #PF: error_code(0x0002) - not-present page
  PGD 0 P4D 0
  Oops: 0002 [#1] SMP NOPTI
  CPU: 1 PID: 0 Comm: swapper/1 Kdump: loaded Tainted: P
  RIP: 0010:__hrtimer_run_queues+0x106/0x230

Note that __hrtimer_run_queues+0x106 is __hrtimer_run_queues+262, which is
at the 6th byte of the above CS CALL instruction. Since the CS CALL
instruction occupies 6 bytes, the exception occurred in the middle of that
call instruction.

The root cause is that when using eBPF tools to probe in the middle of a
function, a kprobe with INT3 is used as the underlying implementation.

During single-step emulation of the original CALL instruction,
int3_emulate_call() assumes that the probed CALL instruction is 5 bytes
long. However, the actual CS-prefixed CALL instruction occupies 6 bytes,
so it constructs an incorrect exception return address. When the CPU
returns from the kprobe handler, the next instruction to be executed is at
the address of the last byte of that CS CALL instruction. Coincidentally,
starting from that address, the CPU fetches and decodes a completely
different instruction, which ultimately triggers a kernel crash.

Fix the issue by using the actual instruction length obtained from
the instruction decoder when constructing the exception return
address, rather than relying on the hardcoded CALL_INSN_SIZE macro.

[ mingo: Refined the changelog ]

Fixes: 6256e668b7af ("x86/kprobes: Use int3 instead of debug trap for single-step")
Suggested-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Jinke Han <jinkehan@didiglobal.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://patch.msgid.link/20260908073742.GA10517@didi-ThinkCentre-M920t-N000

1 files changed, 408 insertions, 0 deletions

diff --git a/scripts/generate_rust_analyzer.py b/scripts/generate_rust_analyzer.py
new file mode 100755
index 000000000..dc1219736
--- /dev/null
+++ b/scripts/generate_rust_analyzer.py
@@ -0,0 +1,408 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0
+"""generate_rust_analyzer - Generates the `rust-project.json` file for `rust-analyzer`.
+"""
+
+import argparse
+import json
+import logging
+import os
+import pathlib
+import subprocess
+import sys
+from typing import Dict, Iterable, List, Literal, Optional, TypedDict
+
+def invoke_rustc(args: List[str]) -> str:
+    return subprocess.check_output(
+        [os.environ["RUSTC"]] + args,
+        stdin=subprocess.DEVNULL,
+    ).decode('utf-8').strip()
+
+def args_crates_cfgs(cfgs: List[str]) -> Dict[str, List[str]]:
+    crates_cfgs = {}
+    for cfg in cfgs:
+        crate, vals = cfg.split("=", 1)
+        crates_cfgs[crate] = vals.split()
+
+    return crates_cfgs
+
+def args_crates_envs(envs: List[str]) -> Dict[str, Dict[str, str]]:
+    crates_envs = {}
+    for env in envs:
+        crate, vals = env.split("=", 1)
+        crates_envs[crate] = dict(v.split("=", 1) for v in vals.split())
+
+    return crates_envs
+
+class Dependency(TypedDict):
+    crate: int
+    name: str
+
+
+class Source(TypedDict):
+    include_dirs: List[str]
+    exclude_dirs: List[str]
+
+
+class Crate(TypedDict):
+    display_name: str
+    root_module: str
+    is_workspace_member: bool
+    deps: List[Dependency]
+    cfg: List[str]
+    edition: str
+    env: Dict[str, str]
+
+
+class ProcMacroCrate(Crate):
+    is_proc_macro: Literal[True]
+    proc_macro_dylib_path: str  # `pathlib.Path` is not JSON serializable.
+
+
+class CrateWithGenerated(Crate):
+    source: Source
+
+
+def generate_crates(
+    srctree: pathlib.Path,
+    objtree: pathlib.Path,
+    sysroot_src: pathlib.Path,
+    external_src: Optional[pathlib.Path],
+    cfgs: List[str],
+    envs: List[str],
+    core_edition: str,
+) -> List[Crate]:
+    # Generate the configuration list.
+    generated_cfg = []
+    with open(objtree / "include" / "generated" / "rustc_cfg") as fd:
+        for line in fd:
+            line = line.replace("--cfg=", "")
+            line = line.replace("\n", "")
+            generated_cfg.append(line)
+
+    # Now fill the crates list.
+    crates: List[Crate] = []
+    crates_cfgs = args_crates_cfgs(cfgs)
+    crates_envs = args_crates_envs(envs)
+
+    def get_crate_name(path: pathlib.Path) -> str:
+        return invoke_rustc(["--print", "crate-name", str(path)])
+
+    def build_crate(
+        display_name: str,
+        root_module: pathlib.Path,
+        deps: List[Dependency],
+        *,
+        cfg: Optional[List[str]],
+        is_workspace_member: Optional[bool],
+        edition: Optional[str],
+    ) -> Crate:
+        cfg = cfg if cfg is not None else crates_cfgs.get(display_name, [])
+        is_workspace_member = (
+            is_workspace_member if is_workspace_member is not None else True
+        )
+        edition = edition if edition is not None else "2021"
+        crate_env = {
+            "RUST_MODFILE": "This is only for rust-analyzer",
+            **crates_envs.get(display_name, {}),
+        }
+        return {
+            "display_name": display_name,
+            "root_module": str(root_module),
+            "is_workspace_member": is_workspace_member,
+            "deps": deps,
+            "cfg": cfg,
+            "edition": edition,
+            "env": crate_env,
+        }
+
+    def append_proc_macro_crate(
+        display_name: str,
+        root_module: pathlib.Path,
+        deps: List[Dependency],
+        *,
+        cfg: Optional[List[str]] = None,
+        is_workspace_member: Optional[bool] = None,
+        edition: Optional[str] = None,
+    ) -> Dependency:
+        crate = build_crate(
+            display_name,
+            root_module,
+            deps,
+            cfg=cfg,
+            is_workspace_member=is_workspace_member,
+            edition=edition,
+        )
+        proc_macro_dylib_name = invoke_rustc([
+            "--print",
+            "file-names",
+            "--crate-name",
+            display_name,
+            "--crate-type",
+            "proc-macro",
+            "-",
+        ])
+        proc_macro_crate: ProcMacroCrate = {
+            **crate,
+            "is_proc_macro": True,
+            "proc_macro_dylib_path": str(objtree / "rust" / proc_macro_dylib_name),
+        }
+        return register_crate(proc_macro_crate)
+
+    def register_crate(crate: Crate) -> Dependency:
+        index = len(crates)
+        crates.append(crate)
+        return {"crate": index, "name": crate["display_name"]}
+
+    def append_crate(
+        display_name: str,
+        root_module: pathlib.Path,
+        deps: List[Dependency],
+        *,
+        cfg: Optional[List[str]] = None,
+        is_workspace_member: Optional[bool] = None,
+        edition: Optional[str] = None,
+    ) -> Dependency:
+        return register_crate(
+            build_crate(
+                display_name,
+                root_module,
+                deps,
+                cfg=cfg,
+                is_workspace_member=is_workspace_member,
+                edition=edition,
+            )
+        )
+
+    def append_sysroot_crate(
+        display_name: str,
+        deps: List[Dependency],
+        *,
+        cfg: Optional[List[str]] = None,
+    ) -> Dependency:
+        return append_crate(
+            display_name,
+            sysroot_src / display_name / "src" / "lib.rs",
+            deps,
+            cfg=cfg,
+            is_workspace_member=False,
+            # Miguel Ojeda writes:
+            #
+            # > ... in principle even the sysroot crates may have different
+            # > editions.
+            # >
+            # > For instance, in the move to 2024, it seems all happened at once
+            # > in 1.87.0 in these upstream commits:
+            # >
+            # >     0e071c2c6a58 ("Migrate core to Rust 2024")
+            # >     f505d4e8e380 ("Migrate alloc to Rust 2024")
+            # >     0b2489c226c3 ("Migrate proc_macro to Rust 2024")
+            # >     993359e70112 ("Migrate std to Rust 2024")
+            # >
+            # > But in the previous move to 2021, `std` moved in 1.59.0, while
+            # > the others in 1.60.0:
+            # >
+            # >     b656384d8398 ("Update stdlib to the 2021 edition")
+            # >     06a1c14d52a8 ("Switch all libraries to the 2021 edition")
+            #
+            # Link: https://lore.kernel.org/all/CANiq72kd9bHdKaAm=8xCUhSHMy2csyVed69bOc4dXyFAW4sfuw@mail.gmail.com/
+            #
+            # At the time of writing all rust versions we support build the
+            # sysroot crates with the same edition. We may need to relax this
+            # assumption if future edition moves span multiple rust versions.
+            edition=core_edition,
+        )
+
+    # NB: sysroot crates reexport items from one another so setting up our transitive dependencies
+    # here is important for ensuring that rust-analyzer can resolve symbols. The sources of truth
+    # for this dependency graph are `(sysroot_src / crate / "Cargo.toml" for crate in crates)`.
+    core = append_sysroot_crate("core", [])
+    alloc = append_sysroot_crate("alloc", [core])
+    std = append_sysroot_crate("std", [alloc, core])
+    proc_macro = append_sysroot_crate("proc_macro", [core, std])
+
+    compiler_builtins = append_crate(
+        "compiler_builtins",
+        srctree / "rust" / "compiler_builtins.rs",
+        [core],
+    )
+
+    proc_macro2 = append_crate(
+        "proc_macro2",
+        srctree / "rust" / "proc-macro2" / "lib.rs",
+        [core, alloc, std, proc_macro],
+    )
+
+    quote = append_crate(
+        "quote",
+        srctree / "rust" / "quote" / "lib.rs",
+        [core, alloc, std, proc_macro, proc_macro2],
+        edition="2018",
+    )
+
+    syn = append_crate(
+        "syn",
+        srctree / "rust" / "syn" / "lib.rs",
+        [std, proc_macro, proc_macro2, quote],
+    )
+
+    macros = append_proc_macro_crate(
+        "macros",
+        srctree / "rust" / "macros" / "lib.rs",
+        [std, proc_macro, proc_macro2, quote, syn],
+    )
+
+    zerocopy_derive = append_proc_macro_crate(
+        "zerocopy_derive",
+        srctree / "rust" / "zerocopy-derive" / "lib.rs",
+        [std, proc_macro, proc_macro2, quote, syn],
+    )
+
+    build_error = append_crate(
+        "build_error",
+        srctree / "rust" / "build_error.rs",
+        [core, compiler_builtins],
+    )
+
+    pin_init_internal = append_proc_macro_crate(
+        "pin_init_internal",
+        srctree / "rust" / "pin-init" / "internal" / "src" / "lib.rs",
+        [std, proc_macro, proc_macro2, quote, syn],
+    )
+
+    pin_init = append_crate(
+        "pin_init",
+        srctree / "rust" / "pin-init" / "src" / "lib.rs",
+        [core, compiler_builtins, pin_init_internal, macros],
+    )
+
+    ffi = append_crate(
+        "ffi",
+        srctree / "rust" / "ffi.rs",
+        [core, compiler_builtins],
+    )
+
+    zerocopy = append_crate(
+        "zerocopy",
+        srctree / "rust" / "zerocopy" / "src" / "lib.rs",
+        [core, compiler_builtins],
+    )
+
+    def append_crate_with_generated(
+        display_name: str,
+        deps: List[Dependency],
+    ) -> Dependency:
+        crate = build_crate(
+            display_name,
+            srctree / "rust"/ display_name / "lib.rs",
+            deps,
+            cfg=generated_cfg,
+            is_workspace_member=True,
+            edition=None,
+        )
+        crate["env"]["OBJTREE"] = str(objtree.resolve(True))
+        crate_with_generated: CrateWithGenerated = {
+            **crate,
+            "source": {
+                "include_dirs": [
+                    str(srctree / "rust" / display_name),
+                    str(objtree / "rust"),
+                ],
+                "exclude_dirs": [],
+            },
+        }
+        return register_crate(crate_with_generated)
+
+    bindings = append_crate_with_generated("bindings", [core, ffi, pin_init])
+    uapi = append_crate_with_generated("uapi", [core, ffi, pin_init])
+    kernel = append_crate_with_generated(
+        "kernel", [core, macros, build_error, pin_init, ffi, bindings, uapi, zerocopy, zerocopy_derive]
+    )
+
+    scripts = srctree / "scripts"
+    makefile = (scripts / "Makefile").read_text()
+    for path in scripts.glob("*.rs"):
+        name = path.stem
+        if f"{name}-rust" not in makefile:
+            continue
+        append_crate(
+            name,
+            path,
+            [std],
+        )
+
+    def is_root_crate(build_file: pathlib.Path, target: str) -> bool:
+        try:
+            contents = build_file.read_text()
+        except FileNotFoundError:
+            return False
+        return f"{target}.o" in contents
+
+    # Then, the rest outside of `rust/`.
+    #
+    # We explicitly mention the top-level folders we want to cover.
+    extra_dirs: Iterable[pathlib.Path] = (
+        srctree / dir for dir in ("samples", "drivers")
+    )
+    if external_src is not None:
+        extra_dirs = [external_src]
+    for folder in extra_dirs:
+        for path in folder.rglob("*.rs"):
+            logging.info("Checking %s", path)
+            file_name = path.stem
+
+            # Skip those that are not crate roots.
+            if not is_root_crate(path.parent / "Makefile", file_name) and \
+               not is_root_crate(path.parent / "Kbuild", file_name):
+                continue
+
+            crate_name = get_crate_name(path)
+            logging.info("Adding %s", crate_name)
+            append_crate(
+                crate_name,
+                path,
+                [core, kernel, pin_init, zerocopy, zerocopy_derive],
+                cfg=generated_cfg,
+            )
+
+    return crates
+
+def main() -> None:
+    parser = argparse.ArgumentParser()
+    parser.add_argument('--verbose', '-v', action='store_true')
+    parser.add_argument('--cfgs', action='append', default=[])
+    parser.add_argument('--envs', action='append', default=[])
+    parser.add_argument("core_edition")
+    parser.add_argument("srctree", type=pathlib.Path)
+    parser.add_argument("objtree", type=pathlib.Path)
+    parser.add_argument("sysroot", type=pathlib.Path)
+    parser.add_argument("sysroot_src", type=pathlib.Path)
+    parser.add_argument("exttree", type=pathlib.Path, nargs="?")
+
+    class Args(argparse.Namespace):
+        verbose: bool
+        cfgs: List[str]
+        envs: List[str]
+        srctree: pathlib.Path
+        objtree: pathlib.Path
+        sysroot: pathlib.Path
+        sysroot_src: pathlib.Path
+        exttree: Optional[pathlib.Path]
+        core_edition: str
+
+    args = parser.parse_args(namespace=Args())
+
+    logging.basicConfig(
+        format="[%(asctime)s] [%(levelname)s] %(message)s",
+        level=logging.INFO if args.verbose else logging.WARNING
+    )
+
+    rust_project = {
+        "crates": generate_crates(args.srctree, args.objtree, args.sysroot_src, args.exttree, args.cfgs, args.envs, args.core_edition),
+        "sysroot": str(args.sysroot),
+    }
+
+    json.dump(rust_project, sys.stdout, sort_keys=True, indent=4)
+
+if __name__ == "__main__":
+    main()