Date: Thu, 29 Oct 2015 13:53:25 -0500 From: Alan Cox <alc@rice.edu> To: John Baldwin <jhb@freebsd.org>, Steven Wahl <Steve_Wahl@dell.com> Cc: "svn-src-all@freebsd.org" <svn-src-all@freebsd.org>, "kib@freebsd.org" <kib@freebsd.org>, "cem@freebsd.org" <cem@freebsd.org>, Eric Van Gyzen <Eric.VanGyzen@compellent.com>, "?Alan L. Cox" <alc@freebsd.org> Subject: Re: svn commit: r290130 - head/sys/dev/ntb/ntb_hw Message-ID: <56326B25.8000102@rice.edu> In-Reply-To: <1968754.iCngWsIWpR@ralph.baldwin.cx> References: <bbf3208d2a4d40998c2154402208c016@mspexmb1.Beer.Town> <1968754.iCngWsIWpR@ralph.baldwin.cx>
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On 10/29/2015 12:02, John Baldwin wrote: > On Thursday, October 29, 2015 04:42:20 PM Steven Wahl wrote: >> We ran into this exact problem, pmap_change_attr not working right with large bars. I had been working up to seeing if this compiles on the current head, introducing myself to the community, seeing if this would be accepted. >> >> But looks like it's needed sooner, so in case it might save you some time, here's the patch we developed for this problem. >> >> --> Steve Wahl, Dell Compellent, Eden Prairie, MN > Adding alc@, but on first blush this looks correct to me. I agree. Commit it. >> commit 7d112aa8767390cb9dd020325a9f23aaac7fe5a0 >> Author: swahl <steve_wahl@dell.com> >> Date: Thu Oct 1 14:36:48 2015 -0500 >> >> CQ00492954: FreeBSD traps on call to pmap_change_attr() with large PLX BAR >> >> If an address passed to pmap_change_attr() refers to a virtual address, >> the function must also change the direct mapping of this same >> region (if any) to match, or intel says the result is undefined. >> >> But the original code did not check if the virtual address actually fell >> within the direct mapped region before attempting to make this change. >> The attempt to look up the direct mapped page entries returned NULL, and >> this was dereferenced causing a panic. >> >> This is fixed by checking whether the address is outside of the direct >> mapped range before trying to change the direct mapped entries. >> >> diff --git a/src/sys/amd64/amd64/pmap.c b/src/sys/amd64/amd64/pmap.c >> index fe09ace..dee22de 100644 >> --- a/src/sys/amd64/amd64/pmap.c >> +++ b/src/sys/amd64/amd64/pmap.c >> @@ -6268,7 +6268,7 @@ pmap_change_attr_locked(vm_offset_t va, vm_size_t size, int mode) >> */ >> for (tmpva = base; tmpva < base + size; ) { >> pdpe = pmap_pdpe(kernel_pmap, tmpva); >> - if (*pdpe == 0) >> + if (pdpe == NULL || *pdpe == 0) >> return (EINVAL); >> if (*pdpe & PG_PS) { >> /* >> @@ -6341,7 +6341,8 @@ pmap_change_attr_locked(vm_offset_t va, vm_size_t size, int mode) >> X86_PG_PDE_CACHE); >> changed = TRUE; >> } >> - if (tmpva >= VM_MIN_KERNEL_ADDRESS) { >> + if (tmpva >= VM_MIN_KERNEL_ADDRESS && >> + (*pdpe & PG_PS_FRAME) < dmaplimit) { >> if (pa_start == pa_end) { >> /* Start physical address run. */ >> pa_start = *pdpe & PG_PS_FRAME; >> @@ -6370,7 +6371,8 @@ pmap_change_attr_locked(vm_offset_t va, vm_size_t size, int mode) >> X86_PG_PDE_CACHE); >> changed = TRUE; >> } >> - if (tmpva >= VM_MIN_KERNEL_ADDRESS) { >> + if (tmpva >= VM_MIN_KERNEL_ADDRESS && >> + (*pde & PG_PS_FRAME) < dmaplimit) { >> if (pa_start == pa_end) { >> /* Start physical address run. */ >> pa_start = *pde & PG_PS_FRAME; >> @@ -6397,7 +6399,8 @@ pmap_change_attr_locked(vm_offset_t va, vm_size_t size, int mode) >> X86_PG_PTE_CACHE); >> changed = TRUE; >> } >> - if (tmpva >= VM_MIN_KERNEL_ADDRESS) { >> + if (tmpva >= VM_MIN_KERNEL_ADDRESS && >> + (*pte & PG_FRAME) < dmaplimit) { >> if (pa_start == pa_end) { >> /* Start physical address run. */ >> pa_start = *pte & PG_FRAME; >> >
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