On 2025-02-16 10:49:38+0100, Willy Tarreau wrote:
On Wed, Feb 12, 2025 at 07:49:53PM +0100, Thomas Weißschuh wrote:
+#if defined(_ABIO32)
#define _NOLIBC_SYSCALL_CLOBBERLIST \ "memory", "cc", "at", "v1", "hi", "lo", \ "t0", "t1", "t2", "t3", "t4", "t5", "t6", "t7", "t8", "t9" +#define _NOLIBC_SYSCALL_STACK_RESERVE "addiu $sp, $sp, -32\n" +#define _NOLIBC_SYSCALL_STACK_UNRESERVE "addiu $sp, $sp, 32\n"
+#elif defined(_ABIN32) || defined(_ABI64)
+/* binutils, GCC and clang disagree about register aliases, use numbers instead. */
Is this often encountered despite this ? I guess it can cause portability issues :-/
No idea. It's the first time I saw something like this.
+#if defined(_ABIO32)
#define my_syscall5(num, arg1, arg2, arg3, arg4, arg5) \ ({ \ register long _num __asm__ ("v0") = (num); \
(...)
@@ -178,6 +201,50 @@ _arg4 ? -_num : _num; \ }) +#else
Here you should indicate which ABI is covered by this #else, because one has to go up to previous definitions to figure it's _ABIN32 and _ABI64.
Ack.
+#define my_syscall5(num, arg1, arg2, arg3, arg4, arg5) \ +({ \
- register long _num __asm__ ("v0") = (num); \
- register long _arg1 __asm__ ("$4") = (long)(arg1); \
- register long _arg2 __asm__ ("$5") = (long)(arg2); \
- register long _arg3 __asm__ ("$6") = (long)(arg3); \
- register long _arg4 __asm__ ("$7") = (long)(arg4); \
- register long _arg5 __asm__ ("$8") = (long)(arg5); \
(...)
@@ -190,13 +257,33 @@ void __attribute__((weak, noreturn)) __nolibc_entrypoint __no_stack_protector __ "1:\n" ".cpload $ra\n" "move $a0, $sp\n" /* save stack pointer to $a0, as arg1 of _start_c */
+#if defined(_ABIO32) "addiu $sp, $sp, -4\n" /* space for .cprestore to store $gp */ ".cprestore 0\n" "li $t0, -8\n" "and $sp, $sp, $t0\n" /* $sp must be 8-byte aligned */ "addiu $sp, $sp, -16\n" /* the callee expects to save a0..a3 there */
"lui $t9, %hi(_start_c)\n" /* ABI requires current function address in $t9 */+#else
So same here. I think you should do it for all #else since you're generally grouping 2 ABIs vs one between a #if and a #else and it's not trivial to figure what a #else covers, like below.
Ack.
"daddiu $sp, $sp, -8\n" /* space for .cprestore to store $gp */".cpsetup $ra, 0, 1b\n""li $t0, -16\n""and $sp, $sp, $t0\n" /* $sp must be 16-byte aligned */+#endif
/* ABI requires current function address in $t9 */+#if defined(_ABIO32) || defined(_ABIN32)
"lui $t9, %hi(_start_c)\n"+#else
This one indeed covers only _ABI64
(That is intentional)
"lui $t9, %highest(_start_c)\n""ori $t9, %higher(_start_c)\n""dsll $t9, 0x10\n""ori $t9, %hi(_start_c)\n""dsll $t9, 0x10\n""ori $t9, %lo(_start_c)\n"+#endif
With the tiny details above, this looks fine. It's great that syscall numbers didn't change so that you can cover an extra arch with only a few ifdefs. I have not tested but I guess you did :-) So that's OK for me:
The syscall numbers are different, but the UAPI headers also detect the ABI in use and select the correct numbers.
Acked-by: Willy Tarreau w@1wt.eu
Thanks!