Commit 041fa97c authored by Willy Tarreau's avatar Willy Tarreau Committed by Paul E. McKenney
Browse files

tools/nolibc: add auxiliary vector retrieval for riscv 



In the _start block we now iterate over envp to find the auxiliary
vector after the NULL. The pointer is saved into an _auxv variable
that is marked as weak so that it's accessible from multiple units.
It was tested on riscv64 only.

Signed-off-by: default avatarWilly Tarreau <w@1wt.eu>
Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
parent 59ea1876

tools/include/nolibc/arch-riscv.h

+10 −0
Original line number Diff line number Diff line
@@ -171,6 +171,7 @@ struct sys_stat_struct { 
})



char **environ __attribute__((weak));

const unsigned long *_auxv __attribute__((weak));



/* startup code */

void __attribute__((weak,noreturn,optimize("omit-frame-pointer"))) _start(void)
@@ -185,6 +186,15 @@ void __attribute__((weak,noreturn,optimize("omit-frame-pointer"))) _start(void) 
		"slli  a2, a0, "PTRLOG"\n"   // envp (a2) = SZREG*argc ...

		"add   a2, a2, "SZREG"\n"    //             + SZREG (skip null)

		"add   a2,a2,a1\n"           //             + argv



		"add   a3, a2, zero\n"       // iterate a3 over envp to find auxv (after NULL)

		"0:\n"                       // do {

		"ld    a4, 0(a3)\n"          //   a4 = *a3;

		"add   a3, a3, "SZREG"\n"    //   a3 += sizeof(void*);

		"bne   a4, zero, 0b\n"       // } while (a4);

		"lui   a4, %hi(_auxv)\n"     // a4 = &_auxv (high bits)

		"sd    a3, %lo(_auxv)(a4)\n" // store a3 into _auxv



		"lui a3, %hi(environ)\n"     // a3 = &environ (high bits)

		"sd a2,%lo(environ)(a3)\n"   // store envp(a2) into environ

		"andi  sp,a1,-16\n"          // sp must be 16-byte aligned