Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Fix register clobbers in read_flash asm #14

Open
wants to merge 1 commit into
base: master
Choose a base branch
from
Open

Fix register clobbers in read_flash asm #14

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
19 changes: 8 additions & 11 deletions src/lib.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -357,7 +357,11 @@ pub mod flash {
#[link_section = ".data.ram_func"]
unsafe fn read_flash_inner(cmd: FlashCommand, ptrs: *const FlashFunctionPointers) {
core::arch::asm!(
"mov r10, r0", // cmd
// r6, r7 are LLVM-reserved and can't be marked as a clobber, so save/restore them manually
// (r6 is not actually used, but we need to push two words to maintain stack alignment)
"push {{r6, r7}}",

"mov r7, r0", // cmd
"mov r5, r1", // ptrs

"ldr r4, [r5, #0]",
Expand All @@ -366,8 +370,6 @@ pub mod flash {
"ldr r4, [r5, #4]",
"blx r4", // flash_exit_xip()

"mov r7, r10", // cmd

"movs r4, #0x18",
"lsls r4, r4, #24", // 0x18000000, SSI, RP2040 datasheet 4.10.13

Expand Down Expand Up @@ -453,19 +455,14 @@ pub mod flash {
"ldr r4, [r5, #20]",
"blx r4", // flash_enter_cmd_xip();

"pop {{r6, r7}}",

in("r0") &cmd as *const FlashCommand,
in("r1") ptrs,
out("r2") _,
out("r3") _,
out("r4") _,
// Registers r8-r10 are used to store values
// from r0-r2 in registers not clobbered by
// function calls.
// The values can't be passed in using r8-r10 directly
// due to https://github.com/rust-lang/rust/issues/99071
out("r8") _,
out("r9") _,
out("r10") _,
out("r5") _,
clobber_abi("C"),
);
}
Expand Down