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Message-ID: <trinity-8342f794-8d6e-4046-bd20-2afef4490861-1593261380184@3c-app-gmx-bs50> Date: Sat, 27 Jun 2020 14:36:20 +0200 From: erny hombre <hombre67@....at> To: musl@...ts.openwall.com Subject: clone(),sys_clone() arguments Hello, I am writing an operating system for an ARM processor (Cortex-A9). For the user programs I want to use musl libc. I am adding a layer between musl and my os to translate linux system calls into native system calls. For pthread_create the syscall sys_clone is used. This syscall is not called directly. The library function clone() is used instead. The arguments of clone() and the raw system call sys_clone differ: int clone(int (*fn)(void *), void *child_stack, int flags, void *arg, ... /* pid_t *ptid, struct user_desc *tls, pid_t *ctid */ ); long sys_clone(unsigned long flags, void *child_stack, void *ptid, void *ctid, struct pt_regs *regs); Musl uses __clone to reorder clone() arguments to the arguments expected by sys_clone: /musl-1.2.0/src/thread/arm/clone.s: __clone: stmfd sp!,{r4,r5,r6,r7} mov r7,#120 mov r6,r3 mov r5,r0 mov r0,r2 and r1,r1,#-16 ldr r2,[sp,#16] ldr r3,[sp,#20] ldr r4,[sp,#24] svc 0 ; sys_clone system call ... I think that the last two arguments for sys_clone (r3..ctid, r4..regs) are taken in the wrong order from the clone parameters ([sp,#20]..tls, [sp,#24]..ctid). Do I miss something or is this a bug ?
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