On Sun, Dec 20, 2015 at 12:47:54AM -0500, Mike Frysinger wrote: > i've been playing with ptrace on sparc and trying to use it to watch and > cancel specific syscalls. i have this working for other arches already. [...] > i'm having trouble with canceling of the syscall itself. seems like > no matter what i stuff into o0, the kernel executes the unlink. i've > tried tracing arch/sparc/kernel/syscalls.S and kernel/head_64.S, the > the entry is linux_sparc_syscall32 which calls linux_syscall_trace32, > but it seems like the o0 stuff doesn't seem to work for me. my sparc > asm foo isn't strong enough to figure out what's going wrong :/.
Yes, sparc is odd in this respect: whatever you write to u_regs[] on entering syscall, it doesn't affect syscall number or syscall arguments. -- ldv
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