From 084d6b03446886274f6505588864646c147b9a26 Mon Sep 17 00:00:00 2001
From: 4lDO2 <4lDO2@protonmail.com>
Date: Wed, 12 Jul 2023 15:44:36 +0200
Subject: [PATCH] Some MAP_FIXED optimizations.
---
src/platform/redox/redox-exec/src/lib.rs | 43 +++++++++++++++---------
1 file changed, 27 insertions(+), 16 deletions(-)
diff --git a/src/platform/redox/redox-exec/src/lib.rs b/src/platform/redox/redox-exec/src/lib.rs
index 5b983651c..7420c22b5 100644
--- a/src/platform/redox/redox-exec/src/lib.rs
+++ b/src/platform/redox/redox-exec/src/lib.rs
@@ -1,5 +1,5 @@
#![no_std]
-#![feature(array_chunks, int_roundings, slice_ptr_get)]
+#![feature(array_chunks, int_roundings, let_chains, slice_ptr_get)]
#![forbid(unreachable_patterns)]
extern crate alloc;
@@ -273,25 +273,24 @@ where
let new_page_no = sp / PAGE_SIZE;
let new_page_off = sp % PAGE_SIZE;
- if old_page_no != new_page_no {
- stack_page = None;
- }
-
- let page = if let Some(ref mut page) = stack_page {
- page.as_mut_ptr_slice()
+ let page = if let Some(ref mut page) = stack_page && old_page_no == new_page_no {
+ page
+ } else if let Some(ref mut stack_page) = stack_page {
+ stack_page.remap(new_page_no * PAGE_SIZE, PROT_WRITE)?;
+ stack_page
} else {
let new = MmapGuard::map(*grants_fd, &Map {
offset: new_page_no * PAGE_SIZE,
size: PAGE_SIZE,
- flags: MapFlags::PROT_WRITE,
+ flags: PROT_WRITE,
address: 0, // let kernel decide
})?;
- stack_page.insert(new).as_mut_ptr_slice()
+ stack_page.insert(new)
};
unsafe {
- page.as_mut_ptr().add(new_page_off).cast::<usize>().write(word);
+ page.as_mut_ptr_slice().as_mut_ptr().add(new_page_off).cast::<usize>().write(word);
}
Ok(())
@@ -591,19 +590,31 @@ fn find_free_target_addr(tree: &BTreeMap<usize, usize>, size: usize) -> Option<u
}
pub struct MmapGuard {
+ fd: usize,
base: usize,
size: usize,
- taken: bool,
}
impl MmapGuard {
pub fn map(fd: usize, map: &Map) -> Result<Self> {
Ok(Self {
+ fd,
size: map.size,
- taken: false,
-
base: unsafe { syscall::fmap(fd, map)? },
})
}
+ pub fn remap(&mut self, offset: usize, mut flags: MapFlags) -> Result<()> {
+ flags.remove(MapFlags::MAP_FIXED_NOREPLACE);
+ flags.insert(MapFlags::MAP_FIXED);
+
+ let _new_base = unsafe { syscall::fmap(self.fd, &Map {
+ offset,
+ size: self.size,
+ flags,
+ address: self.base,
+ })? };
+
+ Ok(())
+ }
pub unsafe fn map_mut_anywhere<'a>(fd: usize, offset: usize, size: usize) -> Result<(Self, &'a mut [u8])> {
let mut this = Self::map(fd, &Map {
size,
@@ -624,13 +635,13 @@ impl MmapGuard {
pub fn as_mut_ptr_slice(&mut self) -> *mut [u8] {
core::ptr::slice_from_raw_parts_mut(self.base as *mut u8, self.size)
}
- pub fn take(&mut self) {
- self.taken = true;
+ pub fn take(mut self) {
+ self.size = 0;
}
}
impl Drop for MmapGuard {
fn drop(&mut self) {
- if !self.taken {
+ if self.size != 0 {
let _ = unsafe { syscall::funmap(self.base, self.size) };
}
}
--
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