From: "Tjernlund" <tjernlund@tjernlund.se>
To: "Linuxppc-Dev" <linuxppc-dev@ozlabs.org>
Cc: uclibc@uclibc.org, 'Linh Dang' <linhd@nortel.com>
Subject: Linux process ABI broken in 2.6?
Date: Fri, 9 Dec 2005 00:07:22 +0100 [thread overview]
Message-ID: <000e01c5fc4c$25b17cb0$020120ac@Jocke> (raw)
Seems like ppc32 kernel pass the application entry point address
in r7 and MSR in r8 when starting the application. The source might be
ret_from_syscall, in entry.S:
...
lwz r7,_NIP(r1)
lwz r8,_MSR(r1)
FIX_SRR1(r8, r0)
lwz r2,GPR2(r1)
lwz r1,GPR1(r1)
mtspr SPRN_SRR0,r7
mtspr SPRN_SRR1,r8
SYNC
RFI
I am not convinced this is the source, but a non zero r7
breaks static apps in uClibc.
Is this on purpose and why?
Secion 8.4.1 in
http://refspecs.freestandards.org/LSB_3.1.0/LSB-Core-PPC32/LSB-Core-PPC32.html#PROCESSINITIALIZATION
says:
"Contrary to what is stated in the Registers part of chapter 3 of the System V Application Binary Interface PowerPC Processor
Supplement there are no values set in registers r3, r4, r5, r6 and r7. Instead the values specified to appear in all of those
registers except r7 are placed on the stack. The value to be placed into register r7, the termination function pointer is not passed
to the process."
How do one not pass a termination function in r7 other than setting
r7 to zero?
Jocke
next reply other threads:[~2005-12-08 23:38 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-12-08 23:07 Tjernlund [this message]
2005-12-09 2:05 ` Linux process ABI broken in 2.6? Benjamin Herrenschmidt
2005-12-09 3:16 ` Paul Mackerras
-- strict thread matches above, loose matches on Subject: below --
2005-12-09 11:05 Joakim Tjernlund
2005-12-12 2:28 ` Paul Mackerras
2005-12-11 15:11 Joakim Tjernlund
2005-12-12 8:09 Joakim Tjernlund
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