| Message ID | 5089ddd75a7cb01486f664c025876c803fe26d5b.1687957589.git.falcon@tinylab.org |
|---|---|
| State | New |
| Headers | show |
| Series | [v5,01/14] tools/nolibc: sys.h: add a syscall return helper | expand |
Hi Zhangjin, On Wed, Jun 28, 2023 at 09:37:29PM +0800, Zhangjin Wu wrote: > It is able to pass the 6th argument like the 5th argument via the stack > for mips, let's add a new my_syscall6() now, see [1] for details: > > The mips/o32 system call convention passes arguments 5 through 8 on > the user stack. > > Both mmap() and pselect6() require my_syscall6(). Very interesting, I didn't manage to make it work previously. Did you test it to confirm that it works ? I guess so but since you didn't mention, I preferred to ask. Thanks! Willy
Hi, Willy > Hi Zhangjin, > > On Wed, Jun 28, 2023 at 09:37:29PM +0800, Zhangjin Wu wrote: > > It is able to pass the 6th argument like the 5th argument via the stack > > for mips, let's add a new my_syscall6() now, see [1] for details: > > > > The mips/o32 system call convention passes arguments 5 through 8 on > > the user stack. > > > > Both mmap() and pselect6() require my_syscall6(). > > Very interesting, I didn't manage to make it work previously. Did you > test it to confirm that it works ? I guess so but since you didn't > mention, I preferred to ask. > Yes, I'm curious too ;-) we did add the mmap test cases and run it for mips, as Thomas suggested, we pass a none-zero pa_offset to mmap() to make sure the 6th argument is used. I just re-tested it for mips and printed something like this: 44 mmap_bad = <0xffffffff> EINVAL [OK] 45 munmap_bad = -1 EINVAL [OK] 46 mmap_munmap_good pa_offset: 8192 length: 1 file_size: 12287 = 0 [OK] 47 open_tty = 3 [OK] 48 open_blah = -1 ENOENT [OK] And I also checked the mips support of musl, it evan provide a __syscall7, so, it should be ok ;-) The only difference is, musl provide a different clobber list for '__mips_isa_rev >= 6', I didn't look into the details yet: https://elixir.bootlin.com/musl/latest/source/arch/mips/syscall_arch.h Best regards, Zhangjin > Thanks! > Willy
diff --git a/tools/include/nolibc/arch-mips.h b/tools/include/nolibc/arch-mips.h index 55a9f01825e0..a8b33d6914a4 100644 --- a/tools/include/nolibc/arch-mips.h +++ b/tools/include/nolibc/arch-mips.h @@ -176,6 +176,31 @@ struct sys_stat_struct { _arg4 ? -_num : _num; \ }) +#define my_syscall6(num, arg1, arg2, arg3, arg4, arg5, arg6) \ +({ \ + register long _num __asm__ ("v0") = (num); \ + register long _arg1 __asm__ ("a0") = (long)(arg1); \ + register long _arg2 __asm__ ("a1") = (long)(arg2); \ + register long _arg3 __asm__ ("a2") = (long)(arg3); \ + register long _arg4 __asm__ ("a3") = (long)(arg4); \ + register long _arg5 = (long)(arg5); \ + register long _arg6 = (long)(arg6); \ + \ + __asm__ volatile ( \ + "addiu $sp, $sp, -32\n" \ + "sw %7, 16($sp)\n" \ + "sw %8, 20($sp)\n" \ + "syscall\n " \ + "addiu $sp, $sp, 32\n" \ + : "=r" (_num), "=r"(_arg4) \ + : "0"(_num), \ + "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4), "r"(_arg5), \ + "r"(_arg6) \ + : SYSCALL_CLOBBERLIST \ + ); \ + _arg4 ? -_num : _num; \ +}) + char **environ __attribute__((weak)); const unsigned long *_auxv __attribute__((weak)); diff --git a/tools/include/nolibc/nolibc.h b/tools/include/nolibc/nolibc.h index 05a228a6ee78..1f8d821000ac 100644 --- a/tools/include/nolibc/nolibc.h +++ b/tools/include/nolibc/nolibc.h @@ -13,11 +13,10 @@ * Syscalls are split into 3 levels: * - The lower level is the arch-specific syscall() definition, consisting in * assembly code in compound expressions. These are called my_syscall0() to - * my_syscall6() depending on the number of arguments. The MIPS - * implementation is limited to 5 arguments. All input arguments are cast - * to a long stored in a register. These expressions always return the - * syscall's return value as a signed long value which is often either a - * pointer or the negated errno value. + * my_syscall6() depending on the number of arguments. All input arguments + * are castto a long stored in a register. These expressions always return + * the syscall's return value as a signed long value which is often either + * a pointer or the negated errno value. * * - The second level is mostly architecture-independent. It is made of * static functions called sys_<name>() which rely on my_syscallN()
It is able to pass the 6th argument like the 5th argument via the stack for mips, let's add a new my_syscall6() now, see [1] for details: The mips/o32 system call convention passes arguments 5 through 8 on the user stack. Both mmap() and pselect6() require my_syscall6(). [1]: https://man7.org/linux/man-pages/man2/syscall.2.html Signed-off-by: Zhangjin Wu <falcon@tinylab.org> --- tools/include/nolibc/arch-mips.h | 25 +++++++++++++++++++++++++ tools/include/nolibc/nolibc.h | 9 ++++----- 2 files changed, 29 insertions(+), 5 deletions(-)