gh-128883: Keep the perf trampoline end marker inside its text section

Author: zanieb

Misc/NEWS.d/next/Build/2026-10-21-18-00-00.gh-issue-128883.perf-trampoline.rst

@@ -0,0 +1,2 @@
+Add a byte after the ELF perf trampoline end marker so it does not share
+the following function's address, which BOLT may otherwise move.

Python/asm_trampoline_aarch64.S

@@ -57,6 +57,7 @@ __Py_trampoline_func_end:
 #else
     .globl	_Py_trampoline_func_end
 _Py_trampoline_func_end:
+    .byte 0
     .section        .note.GNU-stack,"",@progbits
 #endif
 

Python/asm_trampoline_riscv64.S

@@ -9,4 +9,5 @@ _Py_trampoline_func_start:
     jr      ra
     .globl	_Py_trampoline_func_end
 _Py_trampoline_func_end:
+    .byte 0
     .section        .note.GNU-stack,"",@progbits

Python/asm_trampoline_x86_64.S

@@ -21,6 +21,7 @@ __Py_trampoline_func_end:
 #else
     .globl	_Py_trampoline_func_end
 _Py_trampoline_func_end:
+    .byte 0
     .section        .note.GNU-stack,"",@progbits
 #endif
 # Note for indicating the assembly code supports CET