On Wed, Feb 14, 2024 at 11:26:39PM +1000, Ronald Monthero wrote: > Hello, > Below is in relation to architecture calling standards table for man > syscall, for the indicated at [1] , [2] and [3] need to be changed > perhaps. ( arg4 of x86-64 architecture needs to be rcx instead of r10 > and the x32 arch table values needs replacement with exx register > naming respectively. And also the return value register table for x32 > needs to be eax and edx for return val and return val2 respectively ) > ------------ > > Arch/ABI arg1 arg2 arg3 arg4 arg5 arg6 arg7 Notes > ───────────────────────────── > ──────── > alpha a0 a1 a2 a3 a4 a5 - > arc r0 r1 r2 r3 r4 r5 - > arm/OABI r0 r1 r2 r3 r4 r5 r6 > arm/EABI r0 r1 r2 r3 r4 r5 r6 > arm64 x0 x1 x2 x3 x4 x5 - > blackfin R0 R1 R2 R3 R4 R5 - > i386 ebx ecx edx esi edi ebp - > ia64 out0 out1 out2 out3 out4 out5 - > m68k d1 d2 d3 d4 d5 a0 - > microblaze r5 r6 r7 r8 r9 r10 - > mips/o32 a0 a1 a2 a3 - - - 1 > mips/n32,64 a0 a1 a2 a3 a4 a5 - > nios2 r4 r5 r6 r7 r8 r9 - > parisc r26 r25 r24 r23 r22 r21 - > powerpc r3 r4 r5 r6 r7 r8 r9 > powerpc64 r3 r4 r5 r6 r7 r8 - > riscv a0 a1 a2 a3 a4 a5 - > s390 r2 r3 r4 r5 r6 r7 - > s390x r2 r3 r4 r5 r6 r7 - > superh r4 r5 r6 r7 r0 r1 r2 > sparc/32 o0 o1 o2 o3 o4 o5 - > sparc/64 o0 o1 o2 o3 o4 o5 - > tile R00 R01 R02 R03 R04 R05 - > x86-64 rdi rsi rdx r10 r8 r9 - > ^^----- ==> need to > be rcx ? << [1] > x32 rdi rsi rdx r10 r8 r9 - ==> to be > exx regs << [2] > > > => For x86-64 architecture the function calling standards > the arg4 register should be rcx On what basis are you suggesting that? [1] says otherwise, and [2] concurs. > > => And for x32 it needs to be replaced with x86 32 bit register variants > as arg1 = edi , arg2 = esi , arg3 = edx, arg4 = ecx I'm pretty sure that x32 ABI uses the same registers as x86_64. strace's src/linux/x32/get_syscall_args.c[3] corroborates that. > 2) Also noticed the return value register table needs similar > change for x86-32 bit > it needs to be eax instead of rax and edx instead of rdx. > > Arch/ABI Instruction System Ret Ret Error Notes > call # val val2 > ───────────────────────────── > > < snipped > > > sparc/32 t 0x10 g1 o0 o1 psr/csr 1, 6 > sparc/64 t 0x6d g1 o0 o1 psr/csr 1, 6 > tile swint1 R10 R00 - R01 1 > x86-64 syscall rax rax rdx - 5 > x32 syscall rax rax rdx - 5 > > ^^^-----^^^--^^^-------------------> << [3] > > => for x32 return register has to be changed as > rax => eax and rdx => edx > Same, x32 ABI is identical to x86_64 in that regard. [1] https://www.uclibc.org/docs/psABI-x86_64.pdf#page=125 [2] https://gitlab.com/strace/strace/-/blob/8fa8a8886966fb873a67074c67eabf6be63535c0/src/linux/x86_64/get_syscall_args.c#L31 [3] https://gitlab.com/strace/strace/-/blob/8fa8a8886966fb873a67074c67eabf6be63535c0/src/linux/x32/get_syscall_args.c#L31
