From 6d23850108b5d3278f5b1cad395ff8da4fdfebeb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Alex=20R=C3=B8nne=20Petersen?= <alex@alexrp.com>
Date: Mon, 12 Aug 2024 04:10:27 +0200
Subject: [PATCH] std.Thread: Explain apparently pointless mips instruction in
 freeAndExit().

https://git.musl-libc.org/cgit/musl/commit/?id=ce3688eca920aa77549323f84e21f33522397115
---
 lib/std/Thread.zig | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/lib/std/Thread.zig b/lib/std/Thread.zig
index dadf50e5ad..8bd3cd7296 100644
--- a/lib/std/Thread.zig
+++ b/lib/std/Thread.zig
@@ -1130,6 +1130,10 @@ const LinuxThreadImpl = struct {
                       [len] "r" (self.mapped.len),
                     : "memory"
                 ),
+                // We set `sp` to the address of the current function as a workaround for a Linux
+                // kernel bug that caused syscalls to return EFAULT if the stack pointer is invalid.
+                // The bug was introduced in 46e12c07b3b9603c60fc1d421ff18618241cb081 and fixed in
+                // 7928eb0370d1133d0d8cd2f5ddfca19c309079d5.
                 .mips, .mipsel => asm volatile (
                     \\  move $sp, $25
                     \\  li $2, 4091 # SYS_munmap