Buildresult: powerpc-fixes/arm64-defconfig/arm64-gcc5 built on Jan 24 2020, 00:31

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Status:	OK
Date/Time:	Jan 24 2020, 00:31
Duration:	0:04:34.376735
Builder:	ka2
Revision:	powerpc/mm/hash: Fix sharing context ids between kernel & userspace (`5d2e5dd5849b4ef5e8ec35e812cdb732c13cd27e)`
Target:	powerpc-fixes/arm64-defconfig/arm64-gcc5
Branch:	powerpc-fixes
Compiler:	arm64-gcc5 (aarch64-linux-gcc.br_real (Buildroot 2016.11-git-00613-ge98b4dd) 5.4.0 / GNU ld (GNU Binutils) 2.25.1)
Config:	defconfig (download)
Log:	Download original Possible warnings (2) drivers/i2c/busses/i2c-sh_mobile.c:399:26: warning: 'data' may be used uninitialized in this function [-Wmaybe-uninitialized] include/linux/spinlock.h:288:3: warning: 'flags' may be used uninitialized in this function [-Wmaybe-uninitialized] Full Log # git rev-parse -q --verify 5d2e5dd5849b4ef5e8ec35e812cdb732c13cd27e^{commit} 5d2e5dd5849b4ef5e8ec35e812cdb732c13cd27e already have revision, skipping fetch # git checkout -q -f -B kisskb 5d2e5dd5849b4ef5e8ec35e812cdb732c13cd27e # git clean -qxdf # < git log -1 # commit 5d2e5dd5849b4ef5e8ec35e812cdb732c13cd27e # Author: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> # Date: Wed Jan 8 11:14:22 2020 +0530 # # powerpc/mm/hash: Fix sharing context ids between kernel & userspace # # Commit 0034d395f89d ("powerpc/mm/hash64: Map all the kernel regions in # the same 0xc range") has a bug in the definition of MIN_USER_CONTEXT. # # The result is that the context id used for the vmemmap and the lowest # context id handed out to userspace are the same. The context id is # essentially the process identifier as far as the first stage of the # MMU translation is concerned. # # This can result in multiple SLB entries with the same VSID (Virtual # Segment ID), accessible to the kernel and some random userspace # process that happens to get the overlapping id, which is not expected # eg: # # 07 c00c000008000000 40066bdea7000500 1T ESID= c00c00 VSID= 66bdea7 LLP:100 # 12 0002000008000000 40066bdea7000d80 1T ESID= 200 VSID= 66bdea7 LLP:100 # # Even though the user process and the kernel use the same VSID, the # permissions in the hash page table prevent the user process from # reading or writing to any kernel mappings. # # It can also lead to SLB entries with different base page size # encodings (LLP), eg: # # 05 c00c000008000000 00006bde0053b500 256M ESID=c00c00000 VSID= 6bde0053b LLP:100 # 09 0000000008000000 00006bde0053bc80 256M ESID= 0 VSID= 6bde0053b LLP: 0 # # Such SLB entries can result in machine checks, eg. as seen on a G5: # # Oops: Machine check, sig: 7 [#1] # BE PAGE SIZE=64K MU-Hash SMP NR_CPUS=4 NUMA Power Mac # NIP: c00000000026f248 LR: c000000000295e58 CTR: 0000000000000000 # REGS: c0000000erfd3d70 TRAP: 0200 Tainted: G M (5.5.0-rcl-gcc-8.2.0-00010-g228b667d8ea1) # MSR: 9000000000109032 <SF,HV,EE,ME,IR,DR,RI> CR: 24282048 XER: 00000000 # DAR: c00c000000612c80 DSISR: 00000400 IRQMASK: 0 # ... # NIP [c00000000026f248] .kmem_cache_free+0x58/0x140 # LR [c088000008295e58] .putname 8x88/0xa # Call Trace: # .putname+0xB8/0xa # .filename_lookup.part.76+0xbe/0x160 # .do_faccessat+0xe0/0x380 # system_call+0x5c/ex68 # # This happens with 256MB segments and 64K pages, as the duplicate VSID # is hit with the first vmemmap segment and the first user segment, and # older 32-bit userspace maps things in the first user segment. # # On other CPUs a machine check is not seen. Instead the userspace # process can get stuck continuously faulting, with the fault never # properly serviced, due to the kernel not understanding that there is # already a HPTE for the address but with inaccessible permissions. # # On machines with 1T segments we've not seen the bug hit other than by # deliberately exercising it. That seems to be just a matter of luck # though, due to the typical layout of the user virtual address space # and the ranges of vmemmap that are typically populated. # # To fix it we add 2 to MIN_USER_CONTEXT. This ensures the lowest # context given to userspace doesn't overlap with the VMEMMAP context, # or with the context for INVALID_REGION_ID. # # Fixes: 0034d395f89d ("powerpc/mm/hash64: Map all the kernel regions in the same 0xc range") # Cc: stable@vger.kernel.org # v5.2+ # Reported-by: Christian Marillat <marillat@debian.org> # Reported-by: Romain Dolbeau <romain@dolbeau.org> # Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> # [mpe: Account for INVALID_REGION_ID, mostly rewrite change log] # Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> # Link: https://lore.kernel.org/r/20200123102547.11623-1-mpe@ellerman.id.au # < /opt/cross/kisskb/br-aarch64-glibc-2016.08-613-ge98b4dd/bin/aarch64-linux-gcc --version # < /opt/cross/kisskb/br-aarch64-glibc-2016.08-613-ge98b4dd/bin/aarch64-linux-ld --version # < git log --format=%s --max-count=1 5d2e5dd5849b4ef5e8ec35e812cdb732c13cd27e # < make -s -j 48 ARCH=arm64 O=/kisskb/build/powerpc-fixes_arm64-defconfig_arm64-gcc5.4 CROSS_COMPILE=/opt/cross/kisskb/br-aarch64-glibc-2016.08-613-ge98b4dd/bin/aarch64-linux- defconfig # make -s -j 48 ARCH=arm64 O=/kisskb/build/powerpc-fixes_arm64-defconfig_arm64-gcc5.4 CROSS_COMPILE=/opt/cross/kisskb/br-aarch64-glibc-2016.08-613-ge98b4dd/bin/aarch64-linux- arch/arm64/Makefile:27: ld does not support --fix-cortex-a53-843419; kernel may be susceptible to erratum arch/arm64/Makefile:38: LSE atomics not supported by binutils /kisskb/src/drivers/i2c/busses/i2c-sh_mobile.c: In function 'sh_mobile_i2c_isr': /kisskb/src/drivers/i2c/busses/i2c-sh_mobile.c:399:26: warning: 'data' may be used uninitialized in this function [-Wmaybe-uninitialized] pd->msg->buf[real_pos] = data; ^ /kisskb/src/drivers/i2c/busses/i2c-sh_mobile.c:372:16: note: 'data' was declared here unsigned char data; ^ In file included from /kisskb/src/include/linux/rwsem.h:16:0, from /kisskb/src/include/linux/notifier.h:15, from /kisskb/src/include/linux/clk.h:14, from /kisskb/src/drivers/tty/serial/sh-sci.c:24: /kisskb/src/drivers/tty/serial/sh-sci.c: In function 'sci_dma_rx_submit': /kisskb/src/include/linux/spinlock.h:288:3: warning: 'flags' may be used uninitialized in this function [-Wmaybe-uninitialized] _raw_spin_unlock_irqrestore(lock, flags); \ ^ /kisskb/src/drivers/tty/serial/sh-sci.c:1352:16: note: 'flags' was declared here unsigned long flags; ^ Completed OK # rm -rf /kisskb/build/powerpc-fixes_arm64-defconfig_arm64-gcc5.4 # Build took: 0:04:34.376735

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