# Re: Crash on FSL Book3E due to pte\_pgprot()? (was Re: \[PATCH v3 12/24\] powerpc/mm: use pte helpers in generic code) - From: Christophe Leroy \ - Date: 2018-10-17 06:00:48 - List: linuxppc-dev - Page: https://ratatoskr.run/linuxppc-dev/2018/10/5410357 - Thread: https://ratatoskr.run/linux-arm-kernel/2018/10/5403454/t.md ```text On 10/17/2018 12:59 AM, Michael Ellerman wrote: > Christophe Leroy [ref] writes: > >> Get rid of platform specific _PAGE_XXXX in powerpc common code and >> use helpers instead. >> >> mm/dump_linuxpagetables.c will be handled separately >> >> Reviewed-by: Aneesh Kumar K.V >> Signed-off-by: Christophe Leroy >> --- >> arch/powerpc/include/asm/book3s/32/pgtable.h | 9 +++------ >> arch/powerpc/include/asm/nohash/32/pgtable.h | 12 ++++++++---- >> arch/powerpc/include/asm/nohash/pgtable.h | 3 +-- >> arch/powerpc/mm/pgtable.c | 21 +++++++-------------- >> arch/powerpc/mm/pgtable_32.c | 15 ++++++++------- >> arch/powerpc/mm/pgtable_64.c | 14 +++++++------- >> arch/powerpc/xmon/xmon.c | 12 +++++++----- >> 7 files changed, 41 insertions(+), 45 deletions(-) > > So turns out this patch *also* breaks my p5020ds :) > > Even with patch 4 merged, see next. > > It's the same crash: > > pcieport 2000:00:00.0: AER enabled with IRQ 480 > Unable to handle kernel paging request for data at address 0x8000080080080000 > Faulting instruction address: 0xc0000000000192cc > 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 4.19.0-rc3-gcc7x-g98c847323b3a #1 > NIP: c0000000000192cc LR: c0000000005d0f9c CTR: 0000000000100000 > REGS: c0000000f31bb400 TRAP: 0300 Not tainted (4.19.0-rc3-gcc7x-g98c847323b3a) > MSR: 0000000080029000 CR: 24000224 XER: 00000000 > DEAR: 8000080080080000 ESR: 0000000000800000 IRQMASK: 0 > GPR00: c0000000005d0f84 c0000000f31bb688 c00000000117dc00 8000080080080000 > GPR04: 0000000000000000 0000000000400000 00000ffbff241010 c0000000f31b8000 > GPR08: 0000000000000000 0000000000100000 0000000000000000 c0000000012d4710 > GPR12: 0000000084000422 c0000000012ff000 c000000000002774 0000000000000000 > GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 > GPR20: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 > GPR24: 0000000000000000 0000000000000000 8000080080080000 c0000000ffff89a8 > GPR28: c0000000f3576400 c0000000f3576410 0000000000400000 c0000000012ecc98 > NIP [c0000000000192cc] ._memset_io+0x6c/0x9c > LR [c0000000005d0f9c] .fsl_qman_probe+0x198/0x928 > Call Trace: > [c0000000f31bb688] [c0000000005d0f84] .fsl_qman_probe+0x180/0x928 (unreliable) > [c0000000f31bb728] [c0000000006432ec] .platform_drv_probe+0x60/0xb4 > [c0000000f31bb7a8] [c00000000064083c] .really_probe+0x294/0x35c > [c0000000f31bb848] [c000000000640d2c] .__driver_attach+0x148/0x14c > [c0000000f31bb8d8] [c00000000063d7dc] .bus_for_each_dev+0xb0/0x118 > [c0000000f31bb988] [c00000000063ff28] .driver_attach+0x34/0x4c > [c0000000f31bba08] [c00000000063f648] .bus_add_driver+0x174/0x2bc > [c0000000f31bbaa8] [c0000000006418bc] .driver_register+0x90/0x180 > [c0000000f31bbb28] [c000000000643270] .__platform_driver_register+0x60/0x7c > [c0000000f31bbba8] [c000000000ee2a70] .fsl_qman_driver_init+0x24/0x38 > [c0000000f31bbc18] [c0000000000023fc] .do_one_initcall+0x64/0x2b8 > [c0000000f31bbcf8] [c000000000e9f480] .kernel_init_freeable+0x3a8/0x494 > [c0000000f31bbda8] [c000000000002798] .kernel_init+0x24/0x148 > [c0000000f31bbe28] [c0000000000009e8] .ret_from_kernel_thread+0x58/0x70 > Instruction dump: > 4e800020 2ba50003 40dd003c 3925fffc 5488402e 7929f082 7d082378 39290001 > 550a801e 7d2903a6 7d4a4378 794a0020 <91430000> 38630004 4200fff8 70a50003 > > > Comparing a working vs broken kernel, it seems to boil down to the fact > that we're filtering out more PTE bits now that we use pte_pgprot() in > ioremap_prot(). > > With the old code we get: > ioremap_prot: addr 0xff800000 flags 0x241215 > ioremap_prot: addr 0xff800000 flags 0x241215 > map_kernel_page: ea 0x8000080080080000 pa 0xff800000 pte 0xff800241215 > > > And now we get: > ioremap_prot: addr 0xff800000 flags 0x241215 pte 0x241215 > ioremap_prot: addr 0xff800000 pte 0x241215 > ioremap_prot: addr 0xff800000 prot 0x241014 > map_kernel_page: ea 0x8000080080080000 pa 0xff800000 pte 0xff800241014 > > So we're losing 0x201, which for nohash book3e is: > > #define _PAGE_PRESENT 0x000001 /* software: pte contains a translation */ > #define _PAGE_PSIZE_4K 0x000200 > > > I haven't worked out if it's one or both of those that matter. At least missing _PAGE_PRESENT is an issue I believe. > > The question is what's the right way to fix it? Should pte_pgprot() not > be filtering those bits out on book3e? I think we should not use pte_pggrot() for that then. What about the below fix ? Christophe From: Christophe Leroy Date: Wed, 17 Oct 2018 05:56:25 +0000 Subject: [PATCH] powerpc/mm: don't use pte_pgprot() in ioremap_prot() pte_pgprot() filters out some required flags like _PAGE_PRESENT. This patch replaces pte_pgprot() by __pgprot(pte_val()) in ioremap_prot() Fixes: 26973fa5ac0e ("powerpc/mm: use pte helpers in generic code") Signed-off-by: Christophe Leroy --- arch/powerpc/mm/pgtable_32.c | 3 ++- arch/powerpc/mm/pgtable_64.c | 4 ++-- 2 files changed, 4 insertions(+), 3 deletions(-) diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c index 5877f5aa8f5d..a606e2f4937b 100644 --- a/arch/powerpc/mm/pgtable_32.c +++ b/arch/powerpc/mm/pgtable_32.c @@ -122,7 +122,8 @@ ioremap_prot(phys_addr_t addr, unsigned long size, unsigned long flags) pte = pte_exprotect(pte); pte = pte_mkprivileged(pte); - return __ioremap_caller(addr, size, pte_pgprot(pte), __builtin_return_address(0)); + return __ioremap_caller(addr, size, __pgprot(pte_val(pte)), + __builtin_return_address(0)); } EXPORT_SYMBOL(ioremap_prot); diff --git a/arch/powerpc/mm/pgtable_64.c b/arch/powerpc/mm/pgtable_64.c index fb1375c07e8c..836bf436cabb 100644 --- a/arch/powerpc/mm/pgtable_64.c +++ b/arch/powerpc/mm/pgtable_64.c @@ -245,8 +245,8 @@ void __iomem * ioremap_prot(phys_addr_t addr, unsigned long size, pte = pte_mkprivileged(pte); if (ppc_md.ioremap) - return ppc_md.ioremap(addr, size, pte_pgprot(pte), caller); - return __ioremap_caller(addr, size, pte_pgprot(pte), caller); + return ppc_md.ioremap(addr, size, __pgprot(pte_val(pte)), caller); + return __ioremap_caller(addr, size, __pgprot(pte_val(pte)), caller); } -- 2.13.3 ```