Re: Toybox make root no longer works as expected

On 7/14/26 03:14, John Paul Adrian Glaubitz wrote:
> Hi Florian,
> 
> On Tue, 2026-07-14 at 09:47 +0200, Florian Fuchs wrote:
>>> OK, for some reason it works now. Unfortunately, the toolchain doesn't like the current kernel:
>>>
>>>    CC      net/ipv4/inetpeer.o
>>> during RTL pass: final
>>> In file included from kernel/nstree.c:8:
>>> kernel/nstree.c: In function '__se_sys_listns':
>>> ./include/linux/syscalls.h:261:9: internal compiler error: in change_address_1, at emit-rtl.c:2275
>>>    261 |         }                                                               \
>>>        |         ^
>>> ./include/linux/syscalls.h:236:9: note: in expansion of macro '__SYSCALL_DEFINEx'
>>>    236 |         __SYSCALL_DEFINEx(x, sname, __VA_ARGS__)
>>>        |         ^~~~~~~~~~~~~~~~~
>>> ./include/linux/syscalls.h:228:36: note: in expansion of macro 'SYSCALL_DEFINEx'
>>>    228 | #define SYSCALL_DEFINE4(name, ...) SYSCALL_DEFINEx(4, _##name, __VA_ARGS__)
>>>        |                                    ^~~~~~~~~~~~~~~
>>> kernel/nstree.c:763:1: note: in expansion of macro 'SYSCALL_DEFINE4'
>>>    763 | SYSCALL_DEFINE4(listns, const struct ns_id_req __user *, req,
>>>        | ^~~~~~~~~~~~~~~
>>> Please submit a full bug report,
>>> with preprocessed source if appropriate.
>>> See <https://gcc.gnu.org/bugs/> for instructions.
>>> {standard input}: Assembler messages:
>>> {standard input}: Warning: end of file not at end of a line; newline inserted
>>> {standard input}:1592: Error: missing operand
>>> {standard input}:1592: Error: invalid operands for opcode
>>> {standard input}:976: Error: displacement to undefined symbol .L339 overflows 12-bit field
>>> {standard input}:1014: Error: displacement to undefined symbol .L459 overflows 12-bit field
>>> {standard input}:1028: Error: displacement to undefined symbol .L340 overflows 12-bit field
>>> {standard input}:1040: Error: displacement to undefined symbol .L461 overflows 12-bit field
>>> {standard input}:1060: Error: displacement to undefined symbol .L462 overflows 12-bit field
>>> {standard input}:1082: Error: displacement to undefined symbol .L463 overflows 12-bit field
>>> {standard input}:1100: Error: displacement to undefined symbol .L252 overflows 12-bit field
>>> {standard input}:1201: Error: displacement to undefined symbol .L286 overflows 12-bit field
>>> {standard input}:1211: Error: displacement to undefined symbol .L468 overflows 12-bit field
>>> {standard input}:1221: Error: displacement to undefined symbol .L298 overflows 12-bit field
>>> {standard input}:1234: Error: displacement to undefined symbol .L469 overflows 12-bit field
>>> {standard input}:1256: Error: displacement to undefined symbol .L349 overflows 12-bit field
>>> {standard input}:1341: Error: displacement to undefined symbol .L314 overflows 12-bit field
>>> {standard input}:1488: Error: displacement to undefined symbol .L454 overflows 8-bit field
>>> {standard input}:1498: Error: displacement to undefined symbol .L471 overflows 8-bit field
>>> make[3]: *** [scripts/Makefile.build:289: kernel/nstree.o] Error 1
>>> make[3]: *** Waiting for unfinished jobs....
>>>
>>> Adrian
>>
>> I also crafted a bit with gcc-17, and my first issue was a duplicate
>> symbols (LPCS0) compiling libgcc like in
>> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89012 I could only work
>> around with explicitly using O1 instead of O2 in INTERNAL_CFLAGS of gcc.
>>
>> And errors with libbacktrace, I worked around by --enable-languages=c
>>
>> I got gcc to not ICE, but it then fails with invalid assembler thats why
>> I became suspicious about the asm in question. turns out, delcaring the
>> adresses as offsetable, seems to "fix" the ICE and compile and work for
>> fdpic, means it is maybe not necessarily only a GCC issue.
>>
>> diff --git a/arch/sh/include/asm/uaccess_32.h b/arch/sh/include/asm/uaccess_32.h
>> index 5d7ddc092afd..cef40414bfb1 100644
>> --- a/arch/sh/include/asm/uaccess_32.h
>> +++ b/arch/sh/include/asm/uaccess_32.h
>> @@ -92,7 +92,7 @@ __asm__ __volatile__( \
>>   	".long	1b + 2, 3b\n\t" \
>>   	".previous" \
>>   	:"=&r" (err), "=&r" (x) \
>> -	:"m" (__m(addr)), "i" (-EFAULT), "0" (err)); })
>> +	:"o" (__m(addr)), "i" (-EFAULT), "0" (err)); })
>>   #else
>>   #define __get_user_u64(x, addr, err) \
>>   ({ \
>> @@ -116,7 +116,7 @@ __asm__ __volatile__( \
>>   	".long	1b + 2, 3b\n\t" \
>>   	".previous" \
>>   	:"=&r" (err), "=&r" (x) \
>> -	:"m" (__m(addr)), "i" (-EFAULT), "0" (err)); })
>> +	:"o" (__m(addr)), "i" (-EFAULT), "0" (err)); })
>>   #endif
>>   
>>   #define __put_user_size(x,ptr,size,retval)		\
>> @@ -196,7 +196,7 @@ __asm__ __volatile__( \
>>   	".long	1b, 3b\n\t" \
>>   	".previous" \
>>   	: "=r" (retval) \
>> -	: "r" (val), "m" (__m(addr)), "i" (-EFAULT), "0" (retval) \
>> +	: "r" (val), "o" (__m(addr)), "i" (-EFAULT), "0" (retval) \
>>           : "memory"); })
>>   #else
>>   #define __put_user_u64(val,addr,retval) \
>> @@ -218,7 +218,7 @@ __asm__ __volatile__( \
>>   	".long	1b, 3b\n\t" \
>>   	".previous" \
>>   	: "=r" (retval) \
>> -	: "r" (val), "m" (__m(addr)), "i" (-EFAULT), "0" (retval) \
>> +	: "r" (val), "o" (__m(addr)), "i" (-EFAULT), "0" (retval) \
>>           : "memory"); })
>>   #endif
>>   
> 
> Thanks a lot for looking into this, I appreciate the help!
> 
> Did you manage to build a J2 toolchain using GCC 17? I have not looked
> into it myself yet due to time constraints, but I would like to switch
> to a newer compiler to build test kernels for my J2.

In theory you can just build an sh2eb-unknown-muslfdpic toolchain 
_without_ specifying --with-cpu=mj2 since j2 is backwards compatible 
with sh2 and the j2 patches mostly just add things like the more 
efficient sh3 shift instruction.

In practice, the first j2 kernel patch we submitted didn't use the 
assembly mnemonic for the cmpxchg instruction (the cas.l stuff in 
arch/sh/include/asm) but instead hardwired in the machine code bytes to 
emit it so the existing gcc/binutils could build it. Alas the kernel 
guys didn't like that, so we started using the cas.l mnemonic the 
vanilla toolchains still doesn't understand, meaning you'll need at 
least the HARD_CAS parts of the patches. Plus I believe there are other 
fdpic bugs that the arm guys introduced, so here's Rich Felker's patch 
stack for gcc-15.1 and binutils-2.44:

https://github.com/richfelker/musl-cross-make/blob/master/patches/binutils-2.44/0001-j2.diff
https://github.com/richfelker/musl-cross-make/blob/master/patches/binutils-2.44/0002-sh-fdpic-pr31619.diff

https://github.com/richfelker/musl-cross-make/blob/master/patches/gcc-15.1.0/0003-j2.diff
https://github.com/richfelker/musl-cross-make/blob/master/patches/gcc-15.1.0/0007-fdpic-unwind.diff
https://github.com/richfelker/musl-cross-make/blob/master/patches/gcc-15.1.0/0008-fdpic-crtstuff-pr114158.diff
https://github.com/richfelker/musl-cross-make/blob/master/patches/gcc-15.1.0/0009-sh-fdpic-pr114641.diff

Rob