Messages in this thread | | | Subject | Re: [PATCH] 2.4 force_successful_syscall() | From | "Aneesh Kumar K.V" <> | Date | 18 Sep 2003 11:31:39 +0530 |
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On Thu, 2003-09-18 at 11:12, Kumar, Aneesh wrote: > On Thu, 2003-09-18 at 01:30, Marcelo Tosatti wrote: > > On Wed, 10 Sep 2003, Bjorn Helgaas wrote: > > > > > Here's a 2.4 backport of this change to 2.5: > > > > > > > > > http://linux.bkbits.net:8080/linux-2.5/cset@1.1046.238.7?nav=index.html > > > > > > Alpha, ppc, and sparc64 define force_successful_syscall_return() in > > 2.5, > > > but since it's not obvious to me how to do it correctly in 2.4, I > left > > > them unchanged. > > > > Whats the reasoning behing this patch? > > IIRC those changes were added to 2.5 by David. Architecture like Ia64 > and Alpha support error return via a different register set ( $19 for > Alpha ). But syscalls like ptrace can have negative return value for > successful returns. So in that particular case $19 is forced to be zero > to indicate it is a successful return. IIUC > force_successful_syscall_return is a wrapper around doing that. On > alpha actually r0 in the stack (regs.r0 ) is made zero which is read in > entry.S and put in $19.
For IA64 I guess it is r10 and regs.r8. May be other can correct me if i am wrong.
-aneesh
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