* Is it possible to call a C function in transfer_to_handler(arch/ppc/kernel/entry.S)? [not found] <200705281730.39257.wangbj@lzu.edu.cn> @ 2007-05-28 9:30 ` Wang, Baojun 2007-05-28 11:28 ` Paul Mackerras 2007-05-28 15:25 ` Nicholas Mc Guire 0 siblings, 2 replies; 3+ messages in thread From: Wang, Baojun @ 2007-05-28 9:30 UTC (permalink / raw) To: ppc-dev; +Cc: Nicholas McGuire [-- Attachment #1: Type: text/plain, Size: 1885 bytes --] hi, list I'm sorry to ask this topic in this mailling list. I've spend more than 2 days try to add a C function call in transfer_to_handler(in arch/ppc/kernel/entry.S) like this: /* cut from arch/ppc/kernel/entry.S */ transfer_to_handler: stw r2,GPR2(r11) stw r12,_NIP(r11) stw r9,_MSR(r11) andi. r2,r9,MSR_PR mfctr r12 mfspr r2,SPRN_XER stw r12,_CTR(r11) stw r2,_XER(r11) mfspr r12,SPRN_SPRG3 addi r2,r12,-THREAD tovirt(r2,r2) /* set r2 to current */ beq 2f /* if from user, fix up THREAD.regs */ #if 1 /* this is add by me */ stwu r1, -16(r1) mflr r0 stw r0, 20(r1) bl emulate_iret lwz r0, 20(r1) mtlr r0 addi r1, r1, 16 #endif addi r11,r1,STACK_FRAME_OVERHEAD stw r11,PT_REGS(r12) The function prolog is taken from a userspace program. this code freeze the system after prints out `emulate_iret' (The only thing function emulate_iret do is print that message). I read the source code from head_44x.S to entry.S, sounds like all registers (r0-r32, and even more such as _LINK, _CTR, etc..) are being saved, does that mean I shouldn't call any C function in transfer_to_handler()? Is there something tricky (or is it possible) to add a C function call? Thanks in advance! regards -- Wang, Baojun Lanzhou University Distributed & Embedded System Lab http://dslab.lzu.edu.cn School of Information Science and Engeneering wangbj@lzu•edu.cn Tianshui South Road 222. Lanzhou 730000 .P.R.China Tel:+86-931-8912025 Fax:+86-931-8912022 [-- Attachment #2: Type: application/pgp-signature, Size: 189 bytes --] ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Is it possible to call a C function in transfer_to_handler(arch/ppc/kernel/entry.S)? 2007-05-28 9:30 ` Is it possible to call a C function in transfer_to_handler(arch/ppc/kernel/entry.S)? Wang, Baojun @ 2007-05-28 11:28 ` Paul Mackerras 2007-05-28 15:25 ` Nicholas Mc Guire 1 sibling, 0 replies; 3+ messages in thread From: Paul Mackerras @ 2007-05-28 11:28 UTC (permalink / raw) To: Wang, Baojun; +Cc: ppc-dev, Nicholas McGuire Wang, Baojun writes: > I'm sorry to ask this topic in this mailling list. I've spend more than 2 > days try to add a C function call in transfer_to_handler(in > arch/ppc/kernel/entry.S) like this: It's not going to work, because the MMU is off at this point. It will explode as soon as the C code tries to touch any external variable. Paul. ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Is it possible to call a C function in transfer_to_handler(arch/ppc/kernel/entry.S)? 2007-05-28 9:30 ` Is it possible to call a C function in transfer_to_handler(arch/ppc/kernel/entry.S)? Wang, Baojun 2007-05-28 11:28 ` Paul Mackerras @ 2007-05-28 15:25 ` Nicholas Mc Guire 1 sibling, 0 replies; 3+ messages in thread From: Nicholas Mc Guire @ 2007-05-28 15:25 UTC (permalink / raw) To: Wang, Baojun; +Cc: ppc-dev, Nicholas McGuire -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 > > I'm sorry to ask this topic in this mailling list. I've spend more than 2 > days try to add a C function call in transfer_to_handler(in > arch/ppc/kernel/entry.S) like this: > Why are you sorry ? This is what this list is for - and if nobody can answer it then its good you sent it - thanks ! <snip...> > #if 1 /* this is add by me */ could you change this to use onle R3-R13 as these are caller safe - My suspicion i sthat you are using R0/1/2 and that is not healthy here. > stwu r1, -16(r1) > mflr r0 > stw r0, 20(r1) > bl emulate_iret > lwz r0, 20(r1) > mtlr r0 > addi r1, r1, 16 > #endif > addi r11,r1,STACK_FRAME_OVERHEAD > stw r11,PT_REGS(r12) > out of PPC too long - but will see if I can find something. hofrat -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.4 (GNU/Linux) iD8DBQFGWvR4nU7rXZKfY2oRArQDAJ99xJOrUlqYpPPuJtoqH27lGeDJ9ACeIj97 1bPlGITc1bVMw1V5YmXnG34= =hvub -----END PGP SIGNATURE----- ^ permalink raw reply [flat|nested] 3+ messages in thread
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2007-05-28 9:30 ` Is it possible to call a C function in transfer_to_handler(arch/ppc/kernel/entry.S)? Wang, Baojun
2007-05-28 11:28 ` Paul Mackerras
2007-05-28 15:25 ` Nicholas Mc Guire
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