Date: Wed, 24 Feb 2010 21:56:13 -0600 From: Nathan Whitehorn <nwhitehorn@freebsd.org> To: Nathan Whitehorn <nwhitehorn@FreeBSD.org> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r204297 - head/sys/powerpc/aim Message-ID: <4B85F4DD.7040400@freebsd.org> In-Reply-To: <201002250353.o1P3rLxX095091@svn.freebsd.org> References: <201002250353.o1P3rLxX095091@svn.freebsd.org>
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I can't seem to type the correct words tonight. This should have read: Move the OEA64 scratchpage to the end of KVA from the beginning, and set its PVO to map physical address 0 instead of kernelstart. This fixes a situation in which a user process could attempt to read this address via KVM, have it fault while being modified, and then panic the kernel because (a) it is supposed to map a valid address and (b) it lies in the no-fault region between VM_MIN_KERNEL_ADDRESS and virtual_avail. While here, move msgbuf and dpcpu back into regular KVA space for consistency with other implementations. -Nathan Nathan Whitehorn wrote: > Author: nwhitehorn > Date: Thu Feb 25 03:53:21 2010 > New Revision: 204297 > URL: http://svn.freebsd.org/changeset/base/204297 > > Log: > Move the OEA64 scratchpage to the end of KVA from the beginning, and set > its PVO to map physical address 0 instead of kernelstart. This fixes a > situation in which a user process could attempt to return this address > via KVM, have it fault while being modified, and then panic the kernel > because (a) it is supposed to map a valid address and (b) it lies in the > no-fault region between VM_MIN_KERNEL_ADDRESS and virtual_avail. > > While here, move msgbuf and dpcpu make into regular KVA space for > consistency with other implementations. > > Modified: > head/sys/powerpc/aim/mmu_oea64.c > > Modified: head/sys/powerpc/aim/mmu_oea64.c > ============================================================================== > --- head/sys/powerpc/aim/mmu_oea64.c Thu Feb 25 03:49:17 2010 (r204296) > +++ head/sys/powerpc/aim/mmu_oea64.c Thu Feb 25 03:53:21 2010 (r204297) > @@ -970,10 +970,10 @@ moea64_bridge_bootstrap(mmu_t mmup, vm_o > > mtx_init(&moea64_scratchpage_mtx, "pvo zero page", NULL, MTX_DEF); > for (i = 0; i < 2; i++) { > - moea64_scratchpage_va[i] = virtual_avail; > - virtual_avail += PAGE_SIZE; > + moea64_scratchpage_va[i] = (virtual_end+1) - PAGE_SIZE; > + virtual_end -= PAGE_SIZE; > > - moea64_kenter(mmup,moea64_scratchpage_va[i],kernelstart); > + moea64_kenter(mmup,moea64_scratchpage_va[i],0); > > LOCK_TABLE(); > moea64_scratchpage_pvo[i] = moea64_pvo_find_va(kernel_pmap, > @@ -1004,20 +1004,25 @@ moea64_bridge_bootstrap(mmu_t mmup, vm_o > * Allocate virtual address space for the message buffer. > */ > pa = msgbuf_phys = moea64_bootstrap_alloc(MSGBUF_SIZE, PAGE_SIZE); > - msgbufp = (struct msgbuf *)msgbuf_phys; > - while (pa - msgbuf_phys < MSGBUF_SIZE) { > - moea64_kenter(mmup, pa, pa); > + msgbufp = (struct msgbuf *)virtual_avail; > + va = virtual_avail; > + virtual_avail += round_page(MSGBUF_SIZE); > + while (va < virtual_avail) { > + moea64_kenter(mmup, va, pa); > pa += PAGE_SIZE; > + va += PAGE_SIZE; > } > > /* > * Allocate virtual address space for the dynamic percpu area. > */ > pa = moea64_bootstrap_alloc(DPCPU_SIZE, PAGE_SIZE); > - dpcpu = (void *)pa; > - while (pa - (vm_offset_t)dpcpu < DPCPU_SIZE) { > - moea64_kenter(mmup, pa, pa); > + dpcpu = (void *)virtual_avail; > + virtual_avail += DPCPU_SIZE; > + while (va < virtual_avail) { > + moea64_kenter(mmup, va, pa); > pa += PAGE_SIZE; > + va += PAGE_SIZE; > } > dpcpu_init(dpcpu, 0); > } >
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