https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=f4ba145056dbe99adf4dbe632bec035e006539f8
commit f4ba145056dbe99adf4dbe632bec035e006539f8
Author: Thirumalai Nagalingam <thirumalai.nagalin...@multicorewareinc.com>
Date: Fri Jun 20 02:12:51 2025 +0530
Aarch64: Add inline assembly pthread wrapper
This patch adds AArch64-specific inline assembly block for the pthread
wrapper used to bootstrap new threads. It sets up the thread stack,
adjusts for __CYGTLS_PADSIZE__, releases the original stack via
VirtualFree, and invokes the target thread function.
Signed-off-by: Thirumalai Nagalingam
<thirumalai.nagalin...@multicorewareinc.com>
Diff:
---
winsup/cygwin/create_posix_thread.cc | 18 +++++++++++++++++-
1 file changed, 17 insertions(+), 1 deletion(-)
diff --git a/winsup/cygwin/create_posix_thread.cc
b/winsup/cygwin/create_posix_thread.cc
index 3fcd61707..592aaf1a5 100644
--- a/winsup/cygwin/create_posix_thread.cc
+++ b/winsup/cygwin/create_posix_thread.cc
@@ -75,7 +75,7 @@ pthread_wrapper (PVOID arg)
/* Initialize new _cygtls. */
_my_tls.init_thread (wrapper_arg.stackbase - __CYGTLS_PADSIZE__,
(DWORD (*)(void*, void*)) wrapper_arg.func);
-#ifdef __x86_64__
+#if defined(__x86_64__)
__asm__ ("\n\
leaq %[WRAPPER_ARG], %%rbx # Load &wrapper_arg into rbx \n\
movq (%%rbx), %%r12 # Load thread func into r12 \n\
@@ -99,6 +99,22 @@ pthread_wrapper (PVOID arg)
call *%%r12 # Call thread func \n"
: : [WRAPPER_ARG] "o" (wrapper_arg),
[CYGTLS] "i" (__CYGTLS_PADSIZE__));
+#elif defined(__aarch64__)
+ /* Sets up a new thread stack, frees the original OS stack,
+ * and calls the thread function with its arg using AArch64 ABI. */
+ __asm__ __volatile__ ("\n\
+ mov x19, %[WRAPPER_ARG] // x19 = &wrapper_arg \n\
+ ldp x0, x10, [x19, #16] // x0 = stackaddr, x10 = stackbase \n\
+ sub sp, x10, %[CYGTLS] // sp = stackbase - (CYGTLS) \n\
+ mov fp, xzr // clear frame pointer (x29) \n\
+ mov x1, xzr // x1 = 0 (dwSize) \n\
+ mov x2, #0x8000 // x2 = MEM_RELEASE \n\
+ bl VirtualFree // free original stack \n\
+ ldp x19, x0, [x19] // x19 = func, x0 = arg \n\
+ blr x19 // call thread function \n"
+ : : [WRAPPER_ARG] "r" (&wrapper_arg),
+ [CYGTLS] "r" (__CYGTLS_PADSIZE__)
+ : "x0", "x1", "x2", "x10", "x19", "x29", "memory");
#else
#error unimplemented for this target
#endif
