diff options
| author | Willy Tarreau <w@1wt.eu> | 2023-01-10 08:24:28 +0100 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2023-01-10 13:33:56 -0800 |
| commit | 59ea1876242163da431026921070282b2d651197 (patch) | |
| tree | 2f2b0259314180ec82dc96ed0e38578eeefc71ce /tools/include | |
| parent | 2a39a53245d2b5eae83c10a67581e8dc6b629b85 (diff) | |
tools/nolibc: add auxiliary vector retrieval for arm
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.
Signed-off-by: Willy Tarreau <w@1wt.eu>
It was tested in arm, thumb1 and thumb2 modes.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'tools/include')
| -rw-r--r-- | tools/include/nolibc/arch-arm.h | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/tools/include/nolibc/arch-arm.h b/tools/include/nolibc/arch-arm.h index 79666b590e87..42499f23e73c 100644 --- a/tools/include/nolibc/arch-arm.h +++ b/tools/include/nolibc/arch-arm.h @@ -197,6 +197,7 @@ 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) @@ -211,6 +212,16 @@ void __attribute__((weak,noreturn,optimize("omit-frame-pointer"))) _start(void) "ldr %r3, 1f\n" // r3 = &environ (see below) "str %r2, [r3]\n" // store envp into environ + "mov r4, r2\n" // search for auxv (follows NULL after last env) + "0:\n" + "mov r5, r4\n" // r5 = r4 + "add r4, r4, #4\n" // r4 += 4 + "ldr r5,[r5]\n" // r5 = *r5 = *(r4-4) + "cmp r5, #0\n" // and stop at NULL after last env + "bne 0b\n" + "ldr %r3, 2f\n" // r3 = &_auxv (low bits) + "str r4, [r3]\n" // store r4 into _auxv + "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) "and %r3, %r3, %r1\n" // so we do sp = r1(=sp) & r3(=-8); @@ -222,6 +233,8 @@ void __attribute__((weak,noreturn,optimize("omit-frame-pointer"))) _start(void) ".align 2\n" // below are the pointers to a few variables "1:\n" ".word environ\n" + "2:\n" + ".word _auxv\n" ); __builtin_unreachable(); } |