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Completely rework fringe::Context and fringe::arch. 

The new design concerns itself with one thing and exactly one thing:
passing values back and forth with an extern "C" function.
This allows to simplify fringe::arch into a single primitive, swap.

Close #21
This commit is contained in:
whitequark 2016-07-16 01:22:41 +00:00 committed by edef
parent 989b1d439c
commit cbe136b762
27 changed files with 339 additions and 467 deletions
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13
Cargo.toml
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@ -15,9 +15,16 @@ optional = true
git = "https://github.com/edef1c/libvalgrind"
rev = "9ef793e9549aabfd2d969615180b69d29ce28d88"
[dependencies.void]
default-features = false
version = "1"
[dev-dependencies]
simd = "0.1"
[features]
default = ["valgrind"]
# These apply only to tests within this library; assembly at -O0 is completely
# unreadable, so use -O1.
[profile.dev]
opt-level = 1
[profile.test]
opt-level = 1

9
README.md
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@ -44,17 +44,10 @@ git = "https://github.com/edef1c/libfringe.git"
### Feature flags
[Cargo's feature flags]: http://doc.crates.io/manifest.html#the-[features]-section
libfringe provides several optional features through [Cargo's feature flags].
libfringe provides some optional features through [Cargo's feature flags].
Currently, all of them are enabled by default.
#### `valgrind`
[Valgrind]: http://valgrind.org
[Valgrind] integration. libfringe will register context stacks with Valgrind.
#### `os`
[Built-in stack allocator]: https://edef1c.github.io/libfringe/fringe/struct.OsStack.html
[Built-in stack allocator] using your your operating system's anonymous memory mapping facility.
Currently only available for Unix.

41
benches/context_new.rs
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@ -1,41 +0,0 @@
// This file is part of libfringe, a low-level green threading library.
// Copyright (c) edef <edef@edef.eu>
// See the LICENSE file included in this distribution.
#![feature(test)]
extern crate test;
extern crate fringe;
use fringe::Context;
static mut ctx_slot: *mut Context<'static, SliceStack<'static>> = 0 as *mut Context<_>;
static mut stack_buf: [u8; 1024] = [0; 1024];
#[bench]
fn context_new(b: &mut test::Bencher) {
b.iter(|| unsafe {
let stack = SliceStack(&mut stack_buf);
let mut ctx = Context::new(stack, move || {
let ctx_ptr = ctx_slot;
loop {
Context::swap(ctx_ptr, ctx_ptr);
}
});
ctx_slot = &mut ctx;
Context::swap(ctx_slot, ctx_slot);
})
}
struct SliceStack<'a>(&'a mut [u8]);
impl<'a> fringe::Stack for SliceStack<'a> {
fn top(&mut self) -> *mut u8 {
unsafe {
self.0.as_mut_ptr().offset(self.0.len() as isize)
}
}
fn limit(&self) -> *const u8 {
self.0.as_ptr()
}
}

29
benches/swap.rs
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@ -1,31 +1,30 @@
// This file is part of libfringe, a low-level green threading library.
// Copyright (c) edef <edef@edef.eu>
// Copyright (c) edef <edef@edef.eu>,
// whitequark <whitequark@whitequark.org>
// See the LICENSE file included in this distribution.
#![feature(test)]
#![cfg(feature = "os")]
extern crate test;
extern crate fringe;
use fringe::Context;
static mut ctx_slot: *mut Context<'static, fringe::OsStack> = 0 as *mut Context<_>;
static mut ctx_slot: *mut Context<fringe::OsStack> = 0 as *mut Context<_>;
#[bench]
fn swap(b: &mut test::Bencher) {
unsafe extern "C" fn loopback(mut arg: usize) -> ! {
// This deliberately does not ignore arg, to measure the time it takes
// to move the return value between registers.
let ctx_ptr = ctx_slot;
loop { arg = Context::swap(ctx_ptr, ctx_ptr, arg) }
}
unsafe {
let stack = fringe::OsStack::new(4 << 20).unwrap();
let mut ctx = Context::new(stack, move || {
let ctx_ptr = ctx_slot;
loop {
Context::swap(ctx_ptr, ctx_ptr);
}
});
let mut ctx = Context::new(stack, loopback);
ctx_slot = &mut ctx;
let ctx_ptr = &mut ctx;
ctx_slot = ctx_ptr;
Context::swap(ctx_ptr, ctx_ptr);
b.iter(|| Context::swap(ctx_ptr, ctx_ptr));
b.iter(|| Context::swap(ctx_ptr, ctx_ptr, 0));
}
}

5
benches/kernel_swap.rs → benches/syscall.rs
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@ -4,11 +4,10 @@
#![cfg(target_os = "linux")]
#![feature(asm, test)]
extern crate test;
use test::Bencher;
#[cfg(target_arch = "x86_64")]
#[bench]
fn kernel_swap(b: &mut Bencher) {
fn syscall(b: &mut test::Bencher) {
b.iter(|| unsafe {
asm!("movq $$102, %rax\n\
syscall"
@ -21,7 +20,7 @@ fn kernel_swap(b: &mut Bencher) {
#[cfg(target_arch = "x86")]
#[bench]
fn kernel_swap(b: &mut Bencher) {
fn syscall(b: &mut test::Bencher) {
b.iter(|| unsafe {
asm!("mov $$24, %eax\n\
int $$0x80"

34
src/arch/common.rs
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@ -1,34 +0,0 @@
// This file is part of libfringe, a low-level green threading library.
// Copyright (c) edef <edef@edef.eu>
// See the LICENSE file included in this distribution.
use core::mem::{size_of, align_of};
use core::cmp::max;
use core::ptr;
use void::{self, Void};
use super::imp::STACK_ALIGN;
pub unsafe extern "C" fn rust_trampoline<F>(f: *const F) -> !
where F: FnOnce() -> Void {
void::unreachable(ptr::read(f)())
}
pub unsafe fn push<T>(spp: &mut *mut usize, value: T) -> *mut T {
let mut sp = *spp as *mut T;
sp = offset_mut(sp, -1);
sp = align_down_mut(sp, max(align_of::<T>(), STACK_ALIGN));
ptr::write(sp, value); // does not attempt to drop old value
*spp = sp as *mut usize;
sp
}
pub fn align_down_mut<T>(sp: *mut T, n: usize) -> *mut T {
let sp = (sp as usize) & !(n - 1);
sp as *mut T
}
// ptr::offset_mut is positive ints only
pub fn offset_mut<T>(ptr: *mut T, count: isize) -> *mut T {
(ptr as isize + count * (size_of::<T>() as isize)) as *mut T
}

22
src/arch/mod.rs
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@ -1,16 +1,18 @@
// This file is part of libfringe, a low-level green threading library.
// Copyright (c) edef <edef@edef.eu>
// Copyright (c) edef <edef@edef.eu>,
// whitequark <whitequark@whitequark.org>
// See the LICENSE file included in this distribution.
pub use self::imp::Registers;
pub use self::imp::*;
unsafe impl Send for Registers {}
mod common;
#[cfg(target_arch = "x86_64")]
#[path = "x86_64/mod.rs"]
mod imp;
// rust-lang/rust#25544
// #[cfg_attr(target_arch = "x86", path = "x86.rs")]
// #[cfg_attr(target_arch = "x86_64", path = "x86_64.rs")]
// mod imp;
#[cfg(target_arch = "x86")]
#[path = "x86/mod.rs"]
#[path = "x86.rs"]
mod imp;
#[cfg(target_arch = "x86_64")]
#[path = "x86_64.rs"]
mod imp;

105
src/arch/x86.rs Normal file
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@ -0,0 +1,105 @@
// This file is part of libfringe, a low-level green threading library.
// Copyright (c) edef <edef@edef.eu>,
// whitequark <whitequark@whitequark.org>
// See the LICENSE file included in this distribution.
//! To understand the code in this file, keep in mind this fact:
//! * i686 SysV C ABI requires the stack to be aligned at function entry,
//! so that `%esp+4` is a multiple of 16. Aligned operands are a requirement
//! of SIMD instructions, and making this the responsibility of the caller
//! avoids having to maintain a frame pointer, which is necessary when
//! a function has to realign the stack from an unknown state.
//! * i686 SysV C ABI passes the first argument on the stack. This is
//! unfortunate, because unlike every other architecture we can't reuse
//! `swap` for the initial call, and so we use a trampoline.
use stack::Stack;
#[derive(Debug)]
pub struct StackPointer(*mut usize);
impl StackPointer {
unsafe fn new(stack: &Stack) -> StackPointer {
StackPointer(stack.top() as *mut usize)
}
unsafe fn push(&mut self, val: usize) {
self.0 = self.0.offset(-1);
*self.0 = val
}
}
pub unsafe fn init(stack: &Stack, f: unsafe extern "C" fn(usize) -> !) -> StackPointer {
let g: usize;
asm!(
r#"
# Push address of the trampoline.
call 1f
# Pop function.
popl %ebx
# Push argument.
pushl %eax
# Call it.
call *%ebx
1:
# Pop address of the trampoline.
popl %eax
"#
: "={eax}" (g)
:
: "memory"
: "volatile"
);
let mut sp = StackPointer::new(stack);
sp.push(0); // alignment
sp.push(0); // alignment
sp.push(0); // alignment
sp.push(f as usize); // function
sp.push(g as usize); // trampoline
sp
}
#[inline(always)]
pub unsafe fn swap(arg: usize, old_sp: &mut StackPointer, new_sp: &StackPointer) -> usize {
let ret: usize;
asm!(
r#"
# Save frame pointer explicitly; LLVM doesn't spill it even if it is
# marked as clobbered.
pushl %ebp
# Push instruction pointer of the old context and switch to
# the new context.
call 1f
# Restore frame pointer.
popl %ebp
# Continue executing old context.
jmp 2f
1:
# Remember stack pointer of the old context, in case %rdx==%rsi.
movl %esp, %ebx
# Load stack pointer of the new context.
movl (%edi), %esp
# Save stack pointer of the old context.
movl %ebx, (%esi)
# Pop instruction pointer of the new context (placed onto stack by
# the call above) and jump there; don't use `ret` to avoid return
# address mispredictions (~8ns on Ivy Bridge).
popl %ebx
jmpl *%ebx
2:
"#
: "={eax}" (ret)
: "{eax}" (arg)
"{esi}" (old_sp)
"{edi}" (new_sp)
: "eax", "ebx", "ecx", "edx", "esi", "edi", //"ebp", "esp",
"mmx0", "mmx1", "mmx2", "mmx3", "mmx4", "mmx5", "mmx6", "mmx7",
"xmm0", "xmm1", "xmm2", "xmm3", "xmm4", "xmm5", "xmm6", "xmm7",
"cc", "fpsr", "flags", "memory"
: "volatile");
ret
}

1
src/arch/x86/.syntastic_asm_config
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@ -1 +0,0 @@
--32

40
src/arch/x86/init.s
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@ -1,40 +0,0 @@
// This file is part of libfringe, a low-level green threading library.
// Copyright (c) edef <edef@edef.eu>
// See the LICENSE file included in this distribution.
//! initialise a new context
//! arguments:
//! * eax: stack pointer
//! * ebx: function pointer
//! * ecx: data pointer
//!
//! return values:
//! * eax: new stack pointer
// switch to the fresh stack
xchg %esp, %eax
// save the data pointer and the function pointer, respectively
pushl %ecx
pushl %ebx
// save the return address, control flow continues at label 1
call 1f
// we arrive here once this context is reactivated (see swap.s)
// restore the function pointer (the data pointer is the first argument, which lives at the top of the stack)
popl %eax
// initialise the frame pointer
movl $$0, %ebp
// call the function pointer with the data pointer (top of the stack is the first argument)
call *%eax
// crash if it ever returns
ud2
1:
// save our neatly-setup new stack
xchg %esp, %eax
// back into Rust-land we go

33
src/arch/x86/mod.rs
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@ -1,33 +0,0 @@
// This file is part of libfringe, a low-level green threading library.
// Copyright (c) edef <edef@edef.eu>
// See the LICENSE file included in this distribution.
pub use self::common::*;
macro_rules! init {
($sp:expr, $f_ptr:expr, $tramp:expr) => {
asm!(include_str!("x86/init.s")
: "={eax}"($sp)
: "{eax}" ($sp),
"{ebx}" ($tramp),
"{ecx}" ($f_ptr)
:
: "volatile")
};
}
macro_rules! swap {
($out_spp:expr, $in_spp:expr) => {
asm!(include_str!("x86/swap.s")
:
: "{eax}" ($out_spp),
"{ebx}" ($in_spp)
: "eax", "ebx", "ecx", "edx", "esi", "edi", //"ebp", "esp",
"mmx0", "mmx1", "mmx2", "mmx3", "mmx4", "mmx5", "mmx6", "mmx7",
"xmm0", "xmm1", "xmm2", "xmm3", "xmm4", "xmm5", "xmm6", "xmm7",
"cc", "fpsr", "eflags"
: "volatile")
};
}
#[path = "../x86_common.rs"]
mod common;

37
src/arch/x86/swap.s
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@ -1,37 +0,0 @@
// This file is part of libfringe, a low-level green threading library.
// Copyright (c) edef <edef@edef.eu>
// See the LICENSE file included in this distribution.
//! switch to a new context
//! arguments:
//! * eax: stack pointer out pointer
//! * ebx: stack pointer in pointer
// save the frame pointer
pushl %ebp
// save the return address to the stack, control flow continues at label 1
call 1f
// we arrive here once this context is reactivated
// restore the frame pointer
popl %ebp
// and we merrily go on our way, back into Rust-land
jmp 2f
1:
// retrieve the new stack pointer
movl (%eax), %edx
// save the old stack pointer
movl %esp, (%ebx)
// switch to the new stack pointer
movl %edx, %esp
// jump into the new context (return to the call point)
// doing this instead of a straight `ret` is 8ns slower,
// presumably because the branch predictor tries to be clever about it
popl %eax
jmpl *%eax
2:

92
src/arch/x86_64.rs Normal file
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@ -0,0 +1,92 @@
// This file is part of libfringe, a low-level green threading library.
// Copyright (c) edef <edef@edef.eu>,
// whitequark <whitequark@whitequark.org>
// See the LICENSE file included in this distribution.
//! To understand the code in this file, keep in mind these two facts:
//! * x86_64 SysV C ABI has a "red zone": 128 bytes under the top of the stack
//! that is defined to be unmolested by signal handlers, interrupts, etc.
//! Leaf functions can use the red zone without adjusting rsp or rbp.
//! * x86_64 SysV C ABI requires the stack to be aligned at function entry,
//! so that (%rsp+8) is a multiple of 16. Aligned operands are a requirement
//! of SIMD instructions, and making this the responsibility of the caller
//! avoids having to maintain a frame pointer, which is necessary when
//! a function has to realign the stack from an unknown state.
//! * x86_64 SysV C ABI passes the first argument in %rdi. We also use %rdi
//! to pass a value while swapping context; this is an arbitrary choice
//! (we clobber all registers and could use any of them) but this allows us
//! to reuse the swap function to perform the initial call.
use stack::Stack;
#[derive(Debug)]
pub struct StackPointer(*mut usize);
impl StackPointer {
unsafe fn new(stack: &Stack) -> StackPointer {
StackPointer(stack.top() as *mut usize)
}
unsafe fn push(&mut self, val: usize) {
self.0 = self.0.offset(-1);
*self.0 = val
}
}
pub unsafe fn init(stack: &Stack, f: unsafe extern "C" fn(usize) -> !) -> StackPointer {
let mut sp = StackPointer::new(stack);
sp.push(0); // alignment
sp.push(f as usize);
sp
}
#[inline(always)]
pub unsafe fn swap(arg: usize, old_sp: &mut StackPointer, new_sp: &StackPointer) -> usize {
let ret: usize;
asm!(
r#"
# Save frame pointer explicitly; LLVM doesn't spill it even if it is
# marked as clobbered.
pushq %rbp
# Push instruction pointer of the old context and switch to
# the new context.
call 1f
# Restore frame pointer.
popq %rbp
# Continue executing old context.
jmp 2f
1:
# Remember stack pointer of the old context, in case %rdx==%rsi.
movq %rsp, %rax
# Load stack pointer of the new context.
movq (%rdx), %rsp
# Save stack pointer of the old context.
movq %rax, (%rsi)
# Pop instruction pointer of the new context (placed onto stack by
# the call above) and jump there; don't use `ret` to avoid return
# address mispredictions (~8ns on Ivy Bridge).
popq %rax
jmpq *%rax
2:
"#
: "={rdi}" (ret)
: "{rdi}" (arg)
"{rsi}" (old_sp)
"{rdx}" (new_sp)
: "rax", "rbx", "rcx", "rdx", "rsi", "rdi", //"rbp", "rsp",
"r8", "r9", "r10", "r11", "r12", "r13", "r14", "r15",
"xmm0", "xmm1", "xmm2", "xmm3", "xmm4", "xmm5", "xmm6", "xmm7",
"xmm8", "xmm9", "xmm10", "xmm11", "xmm12", "xmm13", "xmm14", "xmm15",
"xmm16", "xmm17", "xmm18", "xmm19", "xmm20", "xmm21", "xmm22", "xmm23",
"xmm24", "xmm25", "xmm26", "xmm27", "xmm28", "xmm29", "xmm30", "xmm31"
"cc", "fpsr", "flags", "memory"
// Ideally, we would set the LLVM "noredzone" attribute on this function
// (and it would be propagated to the call site). Unfortunately, rustc
// provides no such functionality. Fortunately, by a lucky coincidence,
// the "alignstack" LLVM inline assembly option does exactly the same
// thing on x86_64.
: "volatile", "alignstack");
ret
}

1
src/arch/x86_64/.syntastic_asm_config
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@ -1 +0,0 @@
--64

41
src/arch/x86_64/init.s
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@ -1,41 +0,0 @@
// This file is part of libfringe, a low-level green threading library.
// Copyright (c) edef <edef@edef.eu>
// See the LICENSE file included in this distribution.
//! initialise a new context
//! arguments:
//! * rdi: stack pointer
//! * rsi: function pointer
//! * rdx: data pointer
//!
//! return values:
//! * rdi: new stack pointer
// switch to the fresh stack
xchg %rsp, %rdi
// save the function pointer the data pointer, respectively
pushq %rsi
pushq %rdx
// save the return address, control flow continues at label 1
call 1f
// we arrive here once this context is reactivated (see swap.s)
// restore the data pointer and the function pointer, respectively
popq %rdi
popq %rax
// initialise the frame pointer
movq $$0, %rbp
// call the function pointer with the data pointer (rdi is the first argument)
call *%rax
// crash if it ever returns
ud2
1:
// save our neatly-setup new stack
xchg %rsp, %rdi
// back into Rust-land we go

36
src/arch/x86_64/mod.rs
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@ -1,36 +0,0 @@
// This file is part of libfringe, a low-level green threading library.
// Copyright (c) edef <edef@edef.eu>
// See the LICENSE file included in this distribution.
pub use self::common::*;
macro_rules! init {
($sp:expr, $f_ptr:expr, $tramp:expr) => {
asm!(include_str!("x86_64/init.s")
: "={rdi}"($sp)
: "{rdi}" ($sp),
"{rsi}" ($tramp),
"{rdx}" ($f_ptr)
:
: "volatile");
}
}
macro_rules! swap {
($out_spp:expr, $in_spp:expr) => {
asm!(include_str!("x86_64/swap.s")
:
: "{rdi}" ($out_spp)
"{rsi}" ($in_spp)
: "rax", "rbx", "rcx", "rdx", "rsi", "rdi", //"rbp", "rsp",
"r8", "r9", "r10", "r11", "r12", "r13", "r14", "r15",
"xmm0", "xmm1", "xmm2", "xmm3", "xmm4", "xmm5", "xmm6", "xmm7",
"xmm8", "xmm9", "xmm10", "xmm11", "xmm12", "xmm13", "xmm14", "xmm15",
"xmm16", "xmm17", "xmm18", "xmm19", "xmm20", "xmm21", "xmm22", "xmm23",
"xmm24", "xmm25", "xmm26", "xmm27", "xmm28", "xmm29", "xmm30", "xmm31"
"cc", "fpsr", "eflags"
: "volatile");
}
}
#[path = "../x86_common.rs"]
mod common;

44
src/arch/x86_64/swap.s
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@ -1,44 +0,0 @@
// This file is part of libfringe, a low-level green threading library.
// Copyright (c) edef <edef@edef.eu>
// See the LICENSE file included in this distribution.
//! switch to a new context
//! arguments:
//! * rdi: stack pointer out pointer
//! * rsi: stack pointer in pointer
// make sure we leave the red zone alone
sub $$128, %rsp
// save the frame pointer
pushq %rbp
// save the return address to the stack, control flow continues at label 1
call 1f
// we arrive here once this context is reactivated
// restore the frame pointer
popq %rbp
// give back the red zone
add $$128, %rsp
// and we merrily go on our way, back into Rust-land
jmp 2f
1:
// retrieve the new stack pointer
movq (%rsi), %rax
// save the old stack pointer
movq %rsp, (%rdi)
// switch to the new stack pointer
movq %rax, %rsp
// jump into the new context (return to the call point)
// doing this instead of a straight `ret` is 8ns faster,
// presumably because the branch predictor tries
// to be clever about it otherwise
popq %rax
jmpq *%rax
2:

35
src/arch/x86_common.rs
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@ -1,35 +0,0 @@
// This file is part of libfringe, a low-level green threading library.
// Copyright (c) 2015, edef <edef@edef.eu>
// See the LICENSE file included in this distribution.
use void::Void;
use stack::Stack;
use arch::common::{push, rust_trampoline};
pub const STACK_ALIGN: usize = 16;
#[derive(Debug)]
pub struct Registers {
stack_pointer: *mut usize
}
impl Registers {
#[inline]
pub unsafe fn new<S, F>(stack: &mut S, f: F) -> Registers
where S: Stack, F: FnOnce() -> Void
{
let mut sp = stack.top() as *mut usize;
let f_ptr = push(&mut sp, f);
init!(sp, f_ptr, rust_trampoline::<F> as unsafe extern "C" fn(*const F) -> !);
Registers {
stack_pointer: sp,
}
}
#[inline(always)]
pub unsafe fn swap(out_regs: *mut Registers, in_regs: *const Registers) {
swap!(&mut (*out_regs).stack_pointer, &(*in_regs).stack_pointer);
}
}

50
src/context.rs
View File

@ -1,13 +1,10 @@
// This file is part of libfringe, a low-level green threading library.
// Copyright (c) edef <edef@edef.eu>
// Copyright (c) edef <edef@edef.eu>,
// whitequark <whitequark@whitequark.org>
// See the LICENSE file included in this distribution.
use core::marker::PhantomData;
use void::Void;
use arch::Registers;
use stack;
use debug::StackId;
use debug;
use arch;
/// Context is the heart of libfringe.
/// A context represents a saved thread of execution, along with a stack.
@ -17,44 +14,41 @@ use debug::StackId;
/// Every operation is unsafe, because libfringe can't make any guarantees
/// about the state of the context.
#[derive(Debug)]
pub struct Context<'a, Stack: stack::Stack> {
regs: Registers,
_stack_id: StackId,
pub struct Context<Stack: stack::Stack> {
stack: Stack,
_ref: PhantomData<&'a ()>
stack_id: debug::StackId,
stack_ptr: arch::StackPointer
}
unsafe impl<'a, Stack> Send for Context<'a, Stack>
unsafe impl<Stack> Send for Context<Stack>
where Stack: stack::Stack + Send {}
impl<'a, Stack> Context<'a, Stack> where Stack: stack::Stack {
/// Create a new Context. When it is swapped into,
/// it will call the passed closure.
#[inline]
pub unsafe fn new<F>(mut stack: Stack, f: F) -> Context<'a, Stack>
where F: FnOnce() -> Void + Send + 'a {
let stack_id = StackId::register(&mut stack);
let regs = Registers::new(&mut stack, f);
impl<Stack> Context<Stack> where Stack: stack::Stack {
/// Create a new Context. When it is swapped into, it will call
/// `f(arg)`, where `arg` is the argument passed to `swap`.
pub unsafe fn new(stack: Stack, f: unsafe extern "C" fn(usize) -> !) -> Context<Stack> {
let stack_id = debug::StackId::register(&stack);
let stack_ptr = arch::init(&stack, f);
Context {
regs: regs,
_stack_id: stack_id,
stack: stack,
_ref: PhantomData
stack_id: stack_id,
stack_ptr: stack_ptr
}
}
/// Unwrap the context, returning the stack it contained.
#[inline]
pub unsafe fn unwrap(self) -> Stack {
self.stack
}
}
impl<'i, InStack> Context<'i, InStack> where InStack: stack::Stack {
impl<OldStack> Context<OldStack> where OldStack: stack::Stack {
/// Switch to in_ctx, saving the current thread of execution to out_ctx.
#[inline(always)]
pub unsafe fn swap<'o, OutStack>(out_ctx: *mut Context<'o, OutStack>, in_ctx: *const Context<'i, InStack>)
where OutStack: stack::Stack {
Registers::swap(&mut (*out_ctx).regs, &(*in_ctx).regs)
pub unsafe fn swap<NewStack>(old_ctx: *mut Context<OldStack>,
new_ctx: *const Context<NewStack>,
arg: usize) -> usize
where NewStack: stack::Stack {
arch::swap(arg, &mut (*old_ctx).stack_ptr, &(*new_ctx).stack_ptr)
}
}

2
src/debug/mod.rs
View File

@ -14,7 +14,7 @@ mod imp {
pub struct StackId;
/// No-op since no valgrind
impl StackId {
pub fn register<Stack: stack::Stack>(_stack: &mut Stack) -> StackId {
pub fn register<Stack: stack::Stack>(_stack: &Stack) -> StackId {
StackId
}
}

2
src/debug/valgrind.rs
View File

@ -11,7 +11,7 @@ pub struct StackId(self::valgrind::Value);
impl StackId {
#[inline(always)]
pub fn register<Stack: stack::Stack>(stack: &mut Stack) -> StackId {
pub fn register<Stack: stack::Stack>(stack: &Stack) -> StackId {
StackId(stack_register(stack.limit(), stack.top()))
}
}

13
src/lib.rs
View File

@ -7,26 +7,17 @@
//! libfringe is a low-level green threading library.
//! It provides only a context-swapping mechanism.
#[cfg(test)]
#[macro_use]
extern crate std;
extern crate void;
pub use context::Context;
pub use stack::Stack;
#[cfg(feature = "os")]
#[cfg(any(unix, windows))]
pub use os::Stack as OsStack;
mod context;
mod stack;
#[cfg(feature = "os")]
#[cfg(any(unix, windows))]
mod os;
mod arch;
mod debug;
#[cfg(not(test))]
mod std { pub use core::*; }

4
src/os/mod.rs
View File

@ -47,13 +47,13 @@ impl Stack {
}
impl stack::Stack for Stack {
fn top(&mut self) -> *mut u8 {
fn top(&self) -> *mut u8 {
unsafe {
self.ptr.offset(self.len as isize)
}
}
fn limit(&self) -> *const u8 {
fn limit(&self) -> *mut u8 {
unsafe {
self.ptr.offset(sys::page_size() as isize)
}

4
src/stack.rs
View File

@ -8,9 +8,9 @@ pub trait Stack {
/// Returns the top of the stack.
/// On all modern architectures, the stack grows downwards,
/// so this is the highest address.
fn top(&mut self) -> *mut u8;
fn top(&self) -> *mut u8;
/// Returns the bottom of the stack.
/// On all modern architectures, the stack grows downwards,
/// so this is the lowest address.
fn limit(&self) -> *const u8;
fn limit(&self) -> *mut u8;
}

26
tests/basic.rs
View File

@ -1,26 +0,0 @@
// This file is part of libfringe, a low-level green threading library.
// Copyright (c) edef <edef@edef.eu>
// See the LICENSE file included in this distribution.
#![feature(thread_local)]
extern crate fringe;
use fringe::Context;
#[thread_local]
static mut ctx_slot: *mut Context<'static, fringe::OsStack> = 0 as *mut Context<_>;
#[test]
fn main() {
unsafe {
let stack = fringe::OsStack::new(4 << 20).unwrap();
let mut ctx = Context::new(stack, move || {
println!("it's alive!");
Context::swap(ctx_slot, ctx_slot);
panic!("Do not come back!")
});
ctx_slot = &mut ctx;
Context::swap(ctx_slot, ctx_slot);
}
}

60
tests/context.rs Normal file
View File

@ -0,0 +1,60 @@
// This file is part of libfringe, a low-level green threading library.
// Copyright (c) edef <edef@edef.eu>,
// whitequark <whitequark@whitequark.org>
// See the LICENSE file included in this distribution.
#![feature(thread_local)]
extern crate simd;
extern crate fringe;
use fringe::Context;
#[thread_local]
static mut ctx_slot: *mut Context<fringe::OsStack> = 0 as *mut Context<_>;
#[test]
fn context() {
unsafe extern "C" fn adder(arg: usize) -> ! {
println!("it's alive! arg: {}", arg);
let arg = Context::swap(ctx_slot, ctx_slot, arg + 1);
println!("still alive! arg: {}", arg);
Context::swap(ctx_slot, ctx_slot, arg + 1);
panic!("i should be dead");
}
unsafe {
let stack = fringe::OsStack::new(4 << 20).unwrap();
let mut ctx = Context::new(stack, adder);
ctx_slot = &mut ctx;
let ret = Context::swap(ctx_slot, ctx_slot, 10);
assert_eq!(ret, 11);
let ret = Context::swap(ctx_slot, ctx_slot, 50);
assert_eq!(ret, 51);
}
}
#[test]
fn simd() {
unsafe extern "C" fn permuter(arg: usize) -> ! {
// This will crash if the stack is not aligned properly.
let x = simd::i32x4::splat(arg as i32);
let y = x * x;
println!("simd result: {:?}", y);
Context::swap(ctx_slot, ctx_slot, 0);
// And try again after a context switch.
let x = simd::i32x4::splat(arg as i32);
let y = x * x;
println!("simd result: {:?}", y);
Context::swap(ctx_slot, ctx_slot, 0);
panic!("i should be dead");
}
unsafe {
let stack = fringe::OsStack::new(4 << 20).unwrap();
let mut ctx = Context::new(stack, permuter);
ctx_slot = &mut ctx;
Context::swap(ctx_slot, ctx_slot, 10);
Context::swap(ctx_slot, ctx_slot, 20);
}
}

19
tests/fpe.rs
View File

@ -12,7 +12,7 @@ use fringe::Context;
use test::black_box;
#[thread_local]
static mut ctx_slot: *mut Context<'static, fringe::OsStack> = 0 as *mut Context<_>;
static mut ctx_slot: *mut Context<fringe::OsStack> = 0 as *mut Context<_>;
const FE_DIVBYZERO: i32 = 0x4;
extern {
@ -22,21 +22,20 @@ extern {
#[test]
#[ignore]
fn fpe() {
unsafe {
let stack = fringe::OsStack::new(4 << 20).unwrap();
let mut ctx = Context::new(stack, move || {
println!("it's alive!");
unsafe extern "C" fn universe_destroyer(_arg: usize) -> ! {
loop {
println!("{:?}", 1.0/black_box(0.0));
Context::swap(ctx_slot, ctx_slot);
Context::swap(ctx_slot, ctx_slot, 0);
}
}
});
unsafe {
let stack = fringe::OsStack::new(4 << 20).unwrap();
let mut ctx = Context::new(stack, universe_destroyer);
ctx_slot = &mut ctx;
Context::swap(ctx_slot, ctx_slot);
Context::swap(ctx_slot, ctx_slot, 0);
feenableexcept(FE_DIVBYZERO);
Context::swap(ctx_slot, ctx_slot);
Context::swap(ctx_slot, ctx_slot, 0);
}
}