Commit a6f29a2c authored by Willy Tarreau's avatar Willy Tarreau Committed by Paul E. McKenney
Browse files

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: default avatarWilly Tarreau <w@1wt.eu>
Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
parent 9b8688c6

tools/include/nolibc/arch-arm.h

+8 −1
Original line number Diff line number Diff line
@@ -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)
@@ -215,6 +219,9 @@ 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();

}