From a6f29a2c41f3d283e78e00dc8974e6efacaccf37 Mon Sep 17 00:00:00 2001 From: Willy Tarreau Date: Tue, 10 Jan 2023 08:24:21 +0100 Subject: [PATCH] tools/nolibc: export environ as a weak symbol on arm The environ is retrieved from the _start code and is easy to store at this moment. Let's declare the variable weak and store the value into it. By not being static it will be visible to all units. By being weak, if some programs already declared it, they will continue to be able to use it. This was tested in arm and thumb1 and thumb2 modes, and for each mode, both with environ inherited from _start and extracted from envp. Signed-off-by: Willy Tarreau Signed-off-by: Paul E. McKenney --- tools/include/nolibc/arch-arm.h | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/tools/include/nolibc/arch-arm.h b/tools/include/nolibc/arch-arm.h index 48bd95492c87e..79666b590e87f 100644 --- a/tools/include/nolibc/arch-arm.h +++ b/tools/include/nolibc/arch-arm.h @@ -196,6 +196,8 @@ struct sys_stat_struct { _arg1; \ }) +char **environ __attribute__((weak)); + /* startup code */ void __attribute__((weak,noreturn,optimize("omit-frame-pointer"))) _start(void) { @@ -206,6 +208,8 @@ void __attribute__((weak,noreturn,optimize("omit-frame-pointer"))) _start(void) "add %r2, %r0, $1\n" // envp = (argc + 1) ... "lsl %r2, %r2, $2\n" // * 4 ... "add %r2, %r2, %r1\n" // + argv + "ldr %r3, 1f\n" // r3 = &environ (see below) + "str %r2, [r3]\n" // store envp into environ "mov %r3, $8\n" // AAPCS : sp must be 8-byte aligned in the "neg %r3, %r3\n" // callee, and bl doesn't push (lr=pc) @@ -215,7 +219,10 @@ void __attribute__((weak,noreturn,optimize("omit-frame-pointer"))) _start(void) "bl main\n" // main() returns the status code, we'll exit with it. "movs r7, $1\n" // NR_exit == 1 "svc $0x00\n" - ); + ".align 2\n" // below are the pointers to a few variables + "1:\n" + ".word environ\n" + ); __builtin_unreachable(); } -- 2.30.2