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SubjectRe: [PATCH v3] powerpc: implement CONFIG_DEBUG_VIRTUAL
Date
Michael Ellerman <mpe@ellerman.id.au> writes:
> Christophe Leroy <christophe.leroy@c-s.fr> writes:
>
>> This patch implements CONFIG_DEBUG_VIRTUAL to warn about
>> incorrect use of virt_to_phys() and page_to_phys()
>
> This commit is breaking my p5020ds booting a 32-bit kernel with:
>
> smp: Bringing up secondary CPUs ...
> __ioremap(): phys addr 0x7fef5000 is RAM lr ioremap_coherent
> Unable to handle kernel paging request for data at address 0x00000000
> Faulting instruction address: 0xc002e950
> Oops: Kernel access of bad area, sig: 11 [#1]
> BE SMP NR_CPUS=24 CoreNet Generic
> Modules linked in:
> CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.20.0-rc2-gcc-7.0.1-00138-g9a0380d299e9 #148
> NIP: c002e950 LR: c002eb20 CTR: 00000001
> REGS: e804bd20 TRAP: 0300 Not tainted (4.20.0-rc2-gcc-7.0.1-00138-g9a0380d299e9)
> MSR: 00021002 <CE,ME> CR: 28004222 XER: 00000000
> DEAR: 00000000 ESR: 00000000
> GPR00: c002eb20 e804bdd0 e8050000 00000000 00021002 00000000 00000050 00021002
> GPR08: 2d3f0000 00000001 00000000 00000004 24000842 00000000 c00026d0 00000000
> GPR16: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000001
> GPR24: 00029002 7fef5140 30000000 00000000 00000000 00000040 00000001 00000000
> NIP [c002e950] smp_85xx_kick_cpu+0x120/0x410
> LR [c002eb20] smp_85xx_kick_cpu+0x2f0/0x410
> Call Trace:
> [e804bdd0] [c002eb20] smp_85xx_kick_cpu+0x2f0/0x410 (unreliable)
> [e804be20] [c0012e38] __cpu_up+0xc8/0x230
> [e804be50] [c0040b34] bringup_cpu+0x34/0x110
> [e804be70] [c00418a8] cpu_up+0x128/0x250
> [e804beb0] [c0b84b14] smp_init+0xc4/0x10c
> [e804bee0] [c0b75c1c] kernel_init_freeable+0xc8/0x250
> [e804bf20] [c00026e8] kernel_init+0x18/0x120
> [e804bf40] [c0011298] ret_from_kernel_thread+0x14/0x1c
> Instruction dump:
> 7fb3e850 57bdd1be 2e1d0000 41d20250 57bd3032 393dffc0 7e6a9b78 5529d1be
> 39290001 7d2903a6 60000000 60000000 <7c0050ac> 394a0040 4200fff8 7c0004ac
> ---[ end trace edcab2a1dfd5b38c ]---
>
>
> Which is obviously this hunk:
>
>> diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c
>> index 4fc77a99c9bf..68d204a45cd0 100644
>> --- a/arch/powerpc/mm/pgtable_32.c
>> +++ b/arch/powerpc/mm/pgtable_32.c
>> @@ -143,7 +143,7 @@ __ioremap_caller(phys_addr_t addr, unsigned long size, pgprot_t prot, void *call
>> * Don't allow anybody to remap normal RAM that we're using.
>> * mem_init() sets high_memory so only do the check after that.
>> */
>> - if (slab_is_available() && (p < virt_to_phys(high_memory)) &&
>> + if (slab_is_available() && virt_addr_valid(p) &&
>> page_is_ram(__phys_to_pfn(p))) {
>> printk("__ioremap(): phys addr 0x%llx is RAM lr %ps\n",
>> (unsigned long long)p, __builtin_return_address(0));
>
>
> I'll try and come up with a fix tomorrow.

Actually I think that change is just wrong. virt_addr_valid() takes a
virtual address, but p is a physical address.

So I'll drop this hunk for now, which makes the patch a no-op when
DEBUG_VIRTUAL is n which is probably the way it should be.

cheers

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