T0b1/wasmtime
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Use the sym operator for inline assembly (#5459)

Browse Source 
* Use the `sym` operator for inline assembly

Avoids extra `#[no_mangle]` functions and undue symbols being exposed
from Wasmtime. This is a newly stabilized feature in Rust 1.66.0. I've
also added a `rust-version` entry to the `wasmtime` crate to try to head
off possible reports in the future about odd error messages or usage of
unstable features if the rustc version is too old.

* Fix a s390x warning

* Add `rust-version` annotation to Wasmtime crate

As the other main entrypoint for embedders.
This commit is contained in:
Alex Crichton
2022-12-16 14:12:24 -06:00
committed by GitHub
parent 25bf8e0e67
commit d9fdbfd50e
12 changed files with 204 additions and 185 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
.github/workflows/main.yml vendored
View File

@@ -77,7 +77,7 @@ jobs:
submodules: true
- uses: ./.github/actions/install-rust
with:
toolchain: nightly-2022-09-07
toolchain: nightly-2022-12-15
# Build C API documentation
- run: curl -L https://sourceforge.net/projects/doxygen/files/rel-1.9.3/doxygen-1.9.3.linux.bin.tar.gz/download | tar xzf -
@@ -197,7 +197,7 @@ jobs:
# flags to rustc.
- uses: ./.github/actions/install-rust
with:
toolchain: nightly-2022-09-07
toolchain: nightly-2022-12-15
- run: cargo install cargo-fuzz --vers "^0.11"
# Install the OCaml packages necessary for fuzz targets that use the
# `wasm-spec-interpreter`.

2
Cargo.toml
View File

@@ -11,6 +11,7 @@ repository = "https://github.com/bytecodealliance/wasmtime"
readme = "README.md"
edition.workspace = true
default-run = "wasmtime"
rust-version.workspace = true
[lib]
doctest = false
@@ -105,6 +106,7 @@ exclude = [
version = "5.0.0"
authors = ["The Wasmtime Project Developers"]
edition = "2021"
rust-version = "1.66.0"
[workspace.dependencies]
wasmtime = { path = "crates/wasmtime", version = "5.0.0", default-features = false }

86
crates/asm-macros/src/lib.rs
View File

@@ -5,51 +5,43 @@
//! attributes correct (e.g. ELF symbols get a size and are flagged as a
//! function) and additionally handles visibility across platforms. All symbols
//! should be visible to Rust but not visible externally outside of a `*.so`.
//!
//! It also exports a an `asm_sym!` macro which can be used to reference symbols
//! from within `global_asm!`-defined functions, and handles adding the leading
//! underscore that macOS prepends to symbols for you.
cfg_if::cfg_if! {
if #[cfg(target_os = "macos")] {
#[macro_export]
macro_rules! asm_func {
($name:expr, $($body:tt)*) => {
std::arch::global_asm!(concat!(
".p2align 4\n",
".private_extern _", $name, "\n",
".global _", $name, "\n",
"_", $name, ":\n",
$($body)*
));
($name:expr, $body:expr $(, $($args:tt)*)?) => {
std::arch::global_asm!(
concat!(
".p2align 4\n",
".private_extern _", $name, "\n",
".global _", $name, "\n",
"_", $name, ":\n",
$body,
),
$($($args)*)?
);
};
}
#[macro_export]
macro_rules! asm_sym {
( $( $name:tt )* ) => ( concat!("_", $( $name )* ) )
}
} else if #[cfg(target_os = "windows")] {
#[macro_export]
macro_rules! asm_func {
($name:expr, $($body:tt)*) => {
std::arch::global_asm!(concat!(
".def ", $name, "\n",
".scl 2\n",
".type 32\n",
".endef\n",
".global ", $name, "\n",
".p2align 4\n",
$name, ":\n",
$($body)*
));
($name:expr, $body:expr $(, $($args:tt)*)?) => {
std::arch::global_asm!(
concat!(
".def ", $name, "\n",
".scl 2\n",
".type 32\n",
".endef\n",
".global ", $name, "\n",
".p2align 4\n",
$name, ":\n",
$body
),
$($($args)*)?
);
};
}
#[macro_export]
macro_rules! asm_sym {
( $( $name:tt )* ) => ( $( $name )* )
}
} else {
// Note that for now this "else" clause just assumes that everything
// other than macOS is ELF and has the various directives here for
@@ -70,22 +62,20 @@ cfg_if::cfg_if! {
#[macro_export]
macro_rules! asm_func {
($name:expr, $($body:tt)*) => {
std::arch::global_asm!(concat!(
".p2align 4\n",
".hidden ", $name, "\n",
".global ", $name, "\n",
$crate::elf_func_type_header!($name),
$name, ":\n",
concat!($($body)*),
".size ", $name, ",.-", $name,
));
($name:expr, $body:expr $(, $($args:tt)*)?) => {
std::arch::global_asm!(
concat!(
".p2align 4\n",
".hidden ", $name, "\n",
".global ", $name, "\n",
$crate::elf_func_type_header!($name),
$name, ":\n",
$body,
".size ", $name, ",.-", $name,
)
$(, $($args)*)?
);
};
}
#[macro_export]
macro_rules! asm_sym {
( $( $name:tt )* ) => ( $( $name )* )
}
}
}

2
crates/fiber/src/unix.rs
View File

@@ -110,6 +110,8 @@ extern "C" {
entry_arg0: *mut u8,
);
fn wasmtime_fiber_switch(top_of_stack: *mut u8);
#[allow(dead_code)] // only used in inline assembly for some platforms
fn wasmtime_fiber_start();
}
extern "C" fn fiber_start<F, A, B, C>(arg0: *mut u8, top_of_stack: *mut u8)

136
crates/fiber/src/unix/aarch64.rs
View File

@@ -18,6 +18,7 @@
// `DW_CFA_AARCH64_negate_ra_state` DWARF operation (aliased with the
// `.cfi_window_save` assembler directive) informs an unwinder about this
use super::wasmtime_fiber_start;
use wasmtime_asm_macros::asm_func;
cfg_if::cfg_if! {
@@ -25,8 +26,8 @@ cfg_if::cfg_if! {
macro_rules! paci1716 { () => ("pacib1716\n"); }
macro_rules! pacisp { () => ("pacibsp\n"); }
macro_rules! autisp { () => ("autibsp\n"); }
macro_rules! sym_adrp { ($s:tt) => (concat!("_", $s, "@PAGE")); }
macro_rules! sym_add { ($s:tt) => (concat!("_", $s, "@PAGEOFF")); }
macro_rules! sym_adrp { ($s:tt) => (concat!($s, "@PAGE")); }
macro_rules! sym_add { ($s:tt) => (concat!($s, "@PAGEOFF")); }
} else {
macro_rules! paci1716 { () => ("pacia1716\n"); }
macro_rules! pacisp { () => ("paciasp\n"); }
@@ -39,52 +40,54 @@ cfg_if::cfg_if! {
// fn(top_of_stack(%x0): *mut u8)
asm_func!(
"wasmtime_fiber_switch",
"
.cfi_startproc
",
pacisp!(),
"
.cfi_window_save
// Save all callee-saved registers on the stack since we're
// assuming they're clobbered as a result of the stack switch.
stp x29, x30, [sp, -16]!
stp x20, x19, [sp, -16]!
stp x22, x21, [sp, -16]!
stp x24, x23, [sp, -16]!
stp x26, x25, [sp, -16]!
stp x28, x27, [sp, -16]!
stp d9, d8, [sp, -16]!
stp d11, d10, [sp, -16]!
stp d13, d12, [sp, -16]!
stp d15, d14, [sp, -16]!
concat!(
"
.cfi_startproc
",
pacisp!(),
"
.cfi_window_save
// Save all callee-saved registers on the stack since we're
// assuming they're clobbered as a result of the stack switch.
stp x29, x30, [sp, -16]!
stp x20, x19, [sp, -16]!
stp x22, x21, [sp, -16]!
stp x24, x23, [sp, -16]!
stp x26, x25, [sp, -16]!
stp x28, x27, [sp, -16]!
stp d9, d8, [sp, -16]!
stp d11, d10, [sp, -16]!
stp d13, d12, [sp, -16]!
stp d15, d14, [sp, -16]!
// Load our previously saved stack pointer to resume to, and save
// off our current stack pointer on where to come back to
// eventually.
ldr x8, [x0, -0x10]
mov x9, sp
str x9, [x0, -0x10]
// Load our previously saved stack pointer to resume to, and save
// off our current stack pointer on where to come back to
// eventually.
ldr x8, [x0, -0x10]
mov x9, sp
str x9, [x0, -0x10]
// Switch to the new stack and restore all our callee-saved
// registers after the switch and return to our new stack.
mov sp, x8
ldp d15, d14, [sp], 16
ldp d13, d12, [sp], 16
ldp d11, d10, [sp], 16
ldp d9, d8, [sp], 16
ldp x28, x27, [sp], 16
ldp x26, x25, [sp], 16
ldp x24, x23, [sp], 16
ldp x22, x21, [sp], 16
ldp x20, x19, [sp], 16
ldp x29, x30, [sp], 16
",
autisp!(),
"
.cfi_window_save
ret
.cfi_endproc
",
// Switch to the new stack and restore all our callee-saved
// registers after the switch and return to our new stack.
mov sp, x8
ldp d15, d14, [sp], 16
ldp d13, d12, [sp], 16
ldp d11, d10, [sp], 16
ldp d9, d8, [sp], 16
ldp x28, x27, [sp], 16
ldp x26, x25, [sp], 16
ldp x24, x23, [sp], 16
ldp x22, x21, [sp], 16
ldp x20, x19, [sp], 16
ldp x29, x30, [sp], 16
",
autisp!(),
"
.cfi_window_save
ret
.cfi_endproc
",
),
);
// fn(
@@ -112,26 +115,29 @@ asm_func!(
#[rustfmt::skip]
asm_func!(
"wasmtime_fiber_init",
"
.cfi_startproc
hint #34 // bti c
sub x16, x0, #16
adrp x17, ", sym_adrp!("wasmtime_fiber_start"), "
add x17, x17, ", sym_add!("wasmtime_fiber_start"), "
",
paci1716!(),
"
str x17, [x16, -0x8] // x17 => lr
str x0, [x16, -0x18] // x0 => x19
stp x2, x1, [x0, -0x38] // x1 => x20, x2 => x21
concat!(
"
.cfi_startproc
hint #34 // bti c
sub x16, x0, #16
adrp x17, ", sym_adrp!("{fiber}"), "
add x17, x17, ", sym_add!("{fiber}"), "
",
paci1716!(),
"
str x17, [x16, -0x8] // x17 => lr
str x0, [x16, -0x18] // x0 => x19
stp x2, x1, [x0, -0x38] // x1 => x20, x2 => x21
// `wasmtime_fiber_switch` has an 0xa0 byte stack, and we add 0x10 more for
// the original reserved 16 bytes.
add x8, x0, -0xb0
str x8, [x0, -0x10]
ret
.cfi_endproc
",
// `wasmtime_fiber_switch` has an 0xa0 byte stack, and we add 0x10 more for
// the original reserved 16 bytes.
add x8, x0, -0xb0
str x8, [x0, -0x10]
ret
.cfi_endproc
",
),
fiber = sym wasmtime_fiber_start,
);
// See the x86_64 file for more commentary on what these CFI directives are

11
crates/fiber/src/unix/riscv64.rs
View File

@@ -92,17 +92,18 @@ asm_func!(
asm_func!(
"wasmtime_fiber_init",
"
lla t0,wasmtime_fiber_start
lla t0,{}
sd t0,-0x18(a0) // ra,first should be wasmtime_fiber_start.
sd a0,-0x20(a0) // fp pointer.
sd a1,-0x28(a0) // entry_point will load to s1.
sd a1,-0x28(a0) // entry_point will load to s1.
sd a2,-0x30(a0) // entry_arg0 will load to s2.
//
//
addi t0,a0,-0xe0
sd t0,-0x10(a0)
ret
",
sym super::wasmtime_fiber_start,
);
asm_func!(
@@ -118,8 +119,8 @@ asm_func!(
0x06, /* DW_OP_deref */ \
0x08, 0xd0 , /* DW_OP_const1u 0xc8 */ \
0x22 /* DW_OP_plus */
.cfi_rel_offset ra,-0x8
.cfi_rel_offset fp,-0x10
.cfi_rel_offset s1,-0x18

5
crates/fiber/src/unix/x86_64.rs
View File

@@ -5,7 +5,7 @@
// all the other bits. Documentation tries to reference various bits here and
// there but try to make sure to read over everything before tweaking things!
use wasmtime_asm_macros::{asm_func, asm_sym};
use wasmtime_asm_macros::asm_func;
// fn(top_of_stack(rdi): *mut u8)
asm_func!(
@@ -58,7 +58,7 @@ asm_func!(
//
// The first 16 bytes of stack are reserved for metadata, so we start
// storing values beneath that.
lea rax, ", asm_sym!("wasmtime_fiber_start"), "[rip]
lea rax, {start}[rip]
mov -0x18[rdi], rax
mov -0x20[rdi], rdi // loaded into rbp during switch
mov -0x28[rdi], rsi // loaded into rbx during switch
@@ -73,6 +73,7 @@ asm_func!(
mov -0x10[rdi], rax
ret
",
start = sym super::wasmtime_fiber_start,
);
// This is a pretty special function that has no real signature. Its use is to

7
crates/runtime/src/libcalls.rs
View File

@@ -104,7 +104,12 @@ pub mod trampolines {
// This will delegate to the outer module to the actual
// implementation and automatically perform `catch_unwind` along
// with conversion of the return value in the face of traps.
#[no_mangle]
//
// Note that rust targets which support `global_asm!` can use
// the `sym` operator to get the symbol here, but other targets
// like s390x need to use outlined assembly files which requires
// `no_mangle`.
#[cfg_attr(target_arch = "s390x", no_mangle)]
unsafe extern "C" fn [<impl_ $name>](
vmctx : *mut VMContext,
$( $pname : libcall!(@ty $param), )*

5
crates/runtime/src/trampolines/aarch64.rs
View File

@@ -112,10 +112,11 @@ macro_rules! wasm_to_libcall_trampoline {
stur lr, [x9, #32]
// Tail call to the actual implementation of this libcall.
b ", wasmtime_asm_macros::asm_sym!(stringify!($libcall_impl)), "
b {}
.cfi_endproc
"
",
sym $libcall_impl
);
};
}

29
crates/runtime/src/trampolines/riscv64.rs
View File

@@ -23,7 +23,7 @@ asm_func!(
// Store the last Wasm SP into the `last_wasm_entry_sp` in the limits, if this
// was core Wasm, otherwise store an invalid sentinal value.
sd t1,40(t0)
ld t0,16(a1)
jr t0
@@ -95,23 +95,26 @@ macro_rules! wasm_to_libcall_trampoline {
($libcall:ident ; $libcall_impl:ident) => {
wasmtime_asm_macros::asm_func!(
stringify!($libcall),
"
.cfi_startproc
concat!(
"
.cfi_startproc
// Load the pointer to `VMRuntimeLimits` in `t0`.
ld t0, 8(a0)
// Load the pointer to `VMRuntimeLimits` in `t0`.
ld t0, 8(a0)
// Store the last Wasm FP into the `last_wasm_exit_fp` in the limits.
sd fp, 24(t0)
// Store the last Wasm FP into the `last_wasm_exit_fp` in the limits.
sd fp, 24(t0)
// Store the last Wasm PC into the `last_wasm_exit_pc` in the limits.
sd ra, 32(t0)
// Store the last Wasm PC into the `last_wasm_exit_pc` in the limits.
sd ra, 32(t0)
// Tail call to the actual implementation of this libcall.
j ", wasmtime_asm_macros::asm_sym!(stringify!($libcall_impl)), "
// Tail call to the actual implementation of this libcall.
j {}
.cfi_endproc
"
.cfi_endproc
",
),
sym $libcall_impl,
);
};
}

101
crates/runtime/src/trampolines/x86_64.rs
View File

@@ -22,27 +22,29 @@ cfg_if::cfg_if! {
#[rustfmt::skip]
asm_func!(
"host_to_wasm_trampoline",
"
.cfi_startproc simple
.cfi_def_cfa_offset 0
concat!(
"
.cfi_startproc simple
.cfi_def_cfa_offset 0
// Load the pointer to `VMRuntimeLimits` in `scratch0`.
mov ", scratch0!(), ", 8[", arg1!(), "]
// Load the pointer to `VMRuntimeLimits` in `scratch0`.
mov ", scratch0!(), ", 8[", arg1!(), "]
// Check to see if this is a core `VMContext` (MAGIC == 'core').
cmp DWORD PTR [", arg0!(), "], 0x65726f63
// Check to see if this is a core `VMContext` (MAGIC == 'core').
cmp DWORD PTR [", arg0!(), "], 0x65726f63
// Store the last Wasm SP into the `last_wasm_entry_sp` in the limits, if this
// was core Wasm, otherwise store an invalid sentinal value.
mov ", scratch1!(), ", -1
cmove ", scratch1!(), ", rsp
mov 40[", scratch0!(), "], ", scratch1!(), "
// Store the last Wasm SP into the `last_wasm_entry_sp` in the limits, if this
// was core Wasm, otherwise store an invalid sentinal value.
mov ", scratch1!(), ", -1
cmove ", scratch1!(), ", rsp
mov 40[", scratch0!(), "], ", scratch1!(), "
// Tail call to the callee function pointer in the vmctx.
jmp 16[", arg1!(), "]
// Tail call to the callee function pointer in the vmctx.
jmp 16[", arg1!(), "]
.cfi_endproc
",
.cfi_endproc
",
),
);
#[cfg(test)]
@@ -64,28 +66,30 @@ mod host_to_wasm_trampoline_offsets_tests {
#[rustfmt::skip]
asm_func!(
"wasm_to_host_trampoline",
"
.cfi_startproc simple
.cfi_def_cfa_offset 0
concat!(
"
.cfi_startproc simple
.cfi_def_cfa_offset 0
// Load the pointer to `VMRuntimeLimits` in `scratch0`.
mov ", scratch0!(), ", 8[", arg1!(), "]
// Load the pointer to `VMRuntimeLimits` in `scratch0`.
mov ", scratch0!(), ", 8[", arg1!(), "]
// Store the last Wasm FP into the `last_wasm_exit_fp` in the limits.
mov 24[", scratch0!(), "], rbp
// Store the last Wasm FP into the `last_wasm_exit_fp` in the limits.
mov 24[", scratch0!(), "], rbp
// Store the last Wasm PC into the `last_wasm_exit_pc` in the limits.
mov ", scratch1!(), ", [rsp]
mov 32[", scratch0!(), "], ", scratch1!(), "
// Store the last Wasm PC into the `last_wasm_exit_pc` in the limits.
mov ", scratch1!(), ", [rsp]
mov 32[", scratch0!(), "], ", scratch1!(), "
// Tail call to the actual host function.
//
// This *must* be a tail call so that we do not push to the stack and mess
// up the offsets of stack arguments (if any).
jmp 8[", arg0!(), "]
// Tail call to the actual host function.
//
// This *must* be a tail call so that we do not push to the stack and mess
// up the offsets of stack arguments (if any).
jmp 8[", arg0!(), "]
.cfi_endproc
",
.cfi_endproc
",
),
);
#[cfg(test)]
@@ -111,25 +115,28 @@ macro_rules! wasm_to_libcall_trampoline {
($libcall:ident ; $libcall_impl:ident) => {
wasmtime_asm_macros::asm_func!(
stringify!($libcall),
"
.cfi_startproc simple
.cfi_def_cfa_offset 0
concat!(
"
.cfi_startproc simple
.cfi_def_cfa_offset 0
// Load the pointer to `VMRuntimeLimits` in `", scratch0!(), "`.
mov ", scratch0!(), ", 8[", arg0!(), "]
// Load the pointer to `VMRuntimeLimits` in `", scratch0!(), "`.
mov ", scratch0!(), ", 8[", arg0!(), "]
// Store the last Wasm FP into the `last_wasm_exit_fp` in the limits.
mov 24[", scratch0!(), "], rbp
// Store the last Wasm FP into the `last_wasm_exit_fp` in the limits.
mov 24[", scratch0!(), "], rbp
// Store the last Wasm PC into the `last_wasm_exit_pc` in the limits.
mov ", scratch1!(), ", [rsp]
mov 32[", scratch0!(), "], ", scratch1!(), "
// Store the last Wasm PC into the `last_wasm_exit_pc` in the limits.
mov ", scratch1!(), ", [rsp]
mov 32[", scratch0!(), "], ", scratch1!(), "
// Tail call to the actual implementation of this libcall.
jmp ", wasmtime_asm_macros::asm_sym!(stringify!($libcall_impl)), "
// Tail call to the actual implementation of this libcall.
jmp {}
.cfi_endproc
",
.cfi_endproc
",
),
sym $libcall_impl
);
};
}

1
crates/wasmtime/Cargo.toml
View File

@@ -8,6 +8,7 @@ license = "Apache-2.0 WITH LLVM-exception"
repository = "https://github.com/bytecodealliance/wasmtime"
readme = "README.md"
edition.workspace = true
rust-version.workspace = true
[package.metadata.docs.rs]
rustdoc-args = ["--cfg", "nightlydoc"]