Messages in this thread |  | | Date | Mon, 3 Mar 2008 15:53:33 -0500 | | From | Mathieu Desnoyers <> | | Subject | Re: bad paravirt/Xen interaction in "x86 - Enhance DEBUG_RODATA support - alternatives" |
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* Jeremy Fitzhardinge (jeremy@goop.org) wrote: > Andi Kleen wrote: >> On Monday 03 March 2008 18:58:03 Jeremy Fitzhardinge wrote: >> >> >>> Perhaps, though that's uncached by default. >>> >> >> ioremap_cached() > > Sure. But given that from the perspective of this problem ioremap* is just > a wrapper for vmap, we may as well use it directly and avoid getting > tangled up in any current or future io-related stuff that ioremap may want > to do. > > J
Would you have a quick hint on why I get a page fault with the following implementation ? There is probably a fundamental detail I missed.
void *__kprobes text_poke(void *addr, const void *opcode, size_t len) { char *vaddr; struct page *pages[1];
BUG_ON(len > sizeof(long)); BUG_ON((((long)addr + len - 1) & ~(sizeof(long) - 1)) - ((long)addr & ~(sizeof(long) - 1))); if (kernel_text_address((unsigned long)addr)) pages[0] = virt_to_page(addr); else vaddr = addr; vaddr = vmap(pages, 1, VM_MAP, PAGE_KERNEL); memcpy(&vaddr[(unsigned long)addr & PAGE_MASK], opcode, len); if (kernel_text_address((unsigned long)addr)) vunmap(vaddr); sync_core(); /* Could also do a CLFLUSH here to speed up CPU recovery; but that causes hangs on some VIA CPUs. */ return addr; }
[ 0.149856] SMP alternatives: switching to UP code [ 0.152009] BUG: unable to handle kernel paging request at b8902000 [ 0.152009] IP: [<c03acfa1>] text_poke+0x85/0xb4 [ 0.152009] *pde = 00000000 [ 0.152009] Oops: 0002 [#1] SMP [ 0.152009] LTT NESTING LEVEL : 0 <0> [ 0.152009] Modules linked in: [ 0.152009] [ 0.152009] Pid: 0, comm: swapper Not tainted (2.6.25-rc3-testssmp #744) [ 0.152009] EIP: 0060:[<c03acfa1>] EFLAGS: 00010002 CPU: 0 [ 0.152009] EIP is at text_poke+0x85/0xb4 [ 0.152009] EAX: f8800000 EBX: 00000001 ECX: 00000001 EDX: f8800000 [ 0.152009] ESI: c04a3fab EDI: b8902000 EBP: c0102114 ESP: c04a3f88 [ 0.152009] DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068 [ 0.152009] Process swapper (pid: 0, ti=c04a2000 task=c04703a0 task.ti=c04a2) [ 0.152009] Stack: 00000163 f8800000 c1002040 c04a400c c04a7cac c0100000 c03 [ 0.152009] 90411244 00000206 c04e072c c17fb72c 0000672c c04aaefe c03 [ 0.152009] c04ab76a c17f5000 c04a896a 00000092 c04a80d7 00000008 000 [ 0.152009] Call Trace: [ 0.152009] [<c03b0139>] _etext+0x0/0xf7ec7 [ 0.152009] [<c0107814>] alternatives_smp_unlock+0x57/0x59 [ 0.152009] [<c04aaefe>] alternative_instructions+0x152/0x157 [ 0.152009] [<c03b0139>] _etext+0x0/0xf7ec7 [ 0.152009] [<c04ab76a>] check_bugs+0x131/0x14e [ 0.152009] [<c04a896a>] start_kernel+0x2d1/0x327 [ 0.152009] [<c04a80d7>] unknown_bootoption+0x0/0x1e3 [ 0.152009] ======================= [ 0.152009] Code: b9 04 00 00 00 ba 01 00 00 00 e8 a6 87 db ff 89 44 24 04 8 [ 0.152009] EIP: [<c03acfa1>] text_poke+0x85/0xb4 SS:ESP 0068:c04a3f88 [ 0.152009] ---[ end trace ca143223eefdc828 ]--- [ 0.152009] Kernel panic - not syncing: Attempted to kill the idle task!
Mathieu
-- Mathieu Desnoyers Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
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