# git rev-parse -q --verify d9da4b51c27d706592a967c45c8525ed4e19bc6a^{commit} d9da4b51c27d706592a967c45c8525ed4e19bc6a already have revision, skipping fetch # git checkout -q -f -B kisskb d9da4b51c27d706592a967c45c8525ed4e19bc6a # git clean -qxdf # < git log -1 # commit d9da4b51c27d706592a967c45c8525ed4e19bc6a # Author: Michael Ellerman # Date: Thu Feb 14 15:00:36 2019 +1100 # # powerpc/64s: Fix possible corruption on big endian due to pgd/pud_present() # # In v4.20 we changed our pgd/pud_present() to check for _PAGE_PRESENT # rather than just checking that the value is non-zero, e.g.: # # static inline int pgd_present(pgd_t pgd) # { # - return !pgd_none(pgd); # + return (pgd_raw(pgd) & cpu_to_be64(_PAGE_PRESENT)); # } # # Unfortunately this is broken on big endian, as the result of the # bitwise && is truncated to int, which is always zero because # _PAGE_PRESENT is 0x8000000000000000ul. This means pgd_present() and # pud_present() are always false at compile time, and the compiler # elides the subsequent code. # # Remarkably with that bug present we are still able to boot and run # with few noticeable effects. However under some work loads we are able # to trigger a warning in the ext4 code: # # WARNING: CPU: 11 PID: 29593 at fs/ext4/inode.c:3927 .ext4_set_page_dirty+0x70/0xb0 # CPU: 11 PID: 29593 Comm: debugedit Not tainted 4.20.0-rc1 #1 # ... # NIP .ext4_set_page_dirty+0x70/0xb0 # LR .set_page_dirty+0xa0/0x150 # Call Trace: # .set_page_dirty+0xa0/0x150 # .unmap_page_range+0xbf0/0xe10 # .unmap_vmas+0x84/0x130 # .unmap_region+0xe8/0x190 # .__do_munmap+0x2f0/0x510 # .__vm_munmap+0x80/0x110 # .__se_sys_munmap+0x14/0x30 # system_call+0x5c/0x70 # # The fix is simple, we need to convert the result of the bitwise && to # an int before returning it. # # Thanks to Erhard, Jan Kara and Aneesh for help with debugging. # # Fixes: da7ad366b497 ("powerpc/mm/book3s: Update pmd_present to look at _PAGE_PRESENT bit") # Cc: stable@vger.kernel.org # v4.20+ # Reported-by: Erhard F. # Reviewed-by: Aneesh Kumar K.V # Signed-off-by: Michael Ellerman # < /opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-gcc --version # < /opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-ld --version # < git log --format=%s --max-count=1 d9da4b51c27d706592a967c45c8525ed4e19bc6a # < make -s -j 120 ARCH=powerpc O=/kisskb/build/powerpc-fixes_85xx_mpc85xx_cds_defconfig_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux- 85xx/mpc85xx_cds_defconfig # make -s -j 120 ARCH=powerpc O=/kisskb/build/powerpc-fixes_85xx_mpc85xx_cds_defconfig_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux- /kisskb/src/arch/powerpc/boot/dts/fsl/mpc8541cds.dts:334.3-21: Warning (pci_device_bus_num): /pci@e0008000/i8259@19000:bus-range: PCI bus number 1 out of range, expected (0 - 0) /kisskb/src/arch/powerpc/boot/dts/fsl/mpc8555cds.dts:334.3-21: Warning (pci_device_bus_num): /pci@e0008000/i8259@19000:bus-range: PCI bus number 1 out of range, expected (0 - 0) INFO: Uncompressed kernel (size 0x4fa394) overlaps the address of the wrapper(0x400000) INFO: Fixing the link_address of wrapper to (0x500000) INFO: Uncompressed kernel (size 0x4fa394) overlaps the address of the wrapper(0x400000) INFO: Fixing the link_address of wrapper to (0x500000) INFO: Uncompressed kernel (size 0x4fa394) overlaps the address of the wrapper(0x400000) INFO: Fixing the link_address of wrapper to (0x500000) Image Name: Linux-5.0.0-rc1-gd9da4b51c27d Created: Sat Feb 16 22:22:36 2019 Image Type: PowerPC Linux Kernel Image (gzip compressed) Data Size: 2607173 Bytes = 2546.07 KiB = 2.49 MiB Load Address: 00500000 Entry Point: 005002a4 INFO: Uncompressed kernel (size 0x4e9c6c) overlaps the address of the wrapper(0x400000) INFO: Fixing the link_address of wrapper to (0x500000) Image Name: Linux-5.0.0-rc1-gd9da4b51c27d Created: Sat Feb 16 22:22:36 2019 Image Type: PowerPC Linux Kernel Image (gzip compressed) Data Size: 2607176 Bytes = 2546.07 KiB = 2.49 MiB Load Address: 00500000 Entry Point: 005002a4 Image Name: Linux-5.0.0-rc1-gd9da4b51c27d Created: Sat Feb 16 22:22:36 2019 Image Type: PowerPC Linux Kernel Image (gzip compressed) Data Size: 2577717 Bytes = 2517.30 KiB = 2.46 MiB Load Address: 00000000 Entry Point: 00000000 Image Name: Linux-5.0.0-rc1-gd9da4b51c27d Created: Sat Feb 16 22:22:36 2019 Image Type: PowerPC Linux Kernel Image (gzip compressed) Data Size: 2607976 Bytes = 2546.85 KiB = 2.49 MiB Load Address: 00500000 Entry Point: 005002a4 Completed OK # rm -rf /kisskb/build/powerpc-fixes_85xx_mpc85xx_cds_defconfig_powerpc-gcc5 # Build took: 0:00:23.807480