Buildresult: powerpc-next/powerpc-allnoconfig/powerpc-gcc4.6 built on Feb 14 2019, 19:44

kisskb

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Status:	OK
Date/Time:	Feb 14 2019, 19:44
Duration:	0:00:11.024647
Builder:	ka1
Revision:	powerpc/ptrace: Simplify vr_get/set() to avoid GCC warning (`bc13f05ffaf016d42536571c2e9173f85cefd47a)`
Target:	powerpc-next/powerpc-allnoconfig/powerpc-gcc4.6
Branch:	powerpc-next
Compiler:	powerpc-gcc4.6 (powerpc-linux-gcc (GCC) 4.6.3 / GNU ld (GNU Binutils) 2.22)
Config:	allnoconfig (download)
Log:	Download original Possible warnings (1) kernel/printk/printk.c:186:16: warning: 'old' may be used uninitialized in this function [-Wuninitialized] Full Log # git rev-parse -q --verify bc13f05ffaf016d42536571c2e9173f85cefd47a^{commit} bc13f05ffaf016d42536571c2e9173f85cefd47a already have revision, skipping fetch # git checkout -q -f -B kisskb bc13f05ffaf016d42536571c2e9173f85cefd47a # git clean -qxdf # < git log -1 # commit bc13f05ffaf016d42536571c2e9173f85cefd47a # Author: Michael Ellerman <mpe@ellerman.id.au> # Date: Thu Feb 14 11:08:29 2019 +1100 # # powerpc/ptrace: Simplify vr_get/set() to avoid GCC warning # # GCC 8 warns about the logic in vr_get/set(), which with -Werror breaks # the build: # # In function ‘user_regset_copyin’, # inlined from ‘vr_set’ at arch/powerpc/kernel/ptrace.c:628:9: # include/linux/regset.h:295:4: error: ‘memcpy’ offset [-527, -529] is # out of the bounds [0, 16] of object ‘vrsave’ with type ‘union # <anonymous>’ [-Werror=array-bounds] # arch/powerpc/kernel/ptrace.c: In function ‘vr_set’: # arch/powerpc/kernel/ptrace.c:623:5: note: ‘vrsave’ declared here # } vrsave; # # This has been identified as a regression in GCC, see GCC bug 88273. # # However we can avoid the warning and also simplify the logic and make # it more robust. # # Currently we pass -1 as end_pos to user_regset_copyout(). This says # "copy up to the end of the regset". # # The definition of the regset is: # [REGSET_VMX] = { # .core_note_type = NT_PPC_VMX, .n = 34, # .size = sizeof(vector128), .align = sizeof(vector128), # .active = vr_active, .get = vr_get, .set = vr_set # }, # # The end is calculated as (n * size), ie. 34 * sizeof(vector128). # # In vr_get/set() we pass start_pos as 33 * sizeof(vector128), meaning # we can copy up to sizeof(vector128) into/out-of vrsave. # # The on-stack vrsave is defined as: # union { # elf_vrreg_t reg; # u32 word; # } vrsave; # # And elf_vrreg_t is: # typedef __vector128 elf_vrreg_t; # # So there is no bug, but we rely on all those sizes lining up, # otherwise we would have a kernel stack exposure/overwrite on our # hands. # # Rather than relying on that we can pass an explict end_pos based on # the sizeof(vrsave). The result should be exactly the same but it's # more obviously not over-reading/writing the stack and it avoids the # compiler warning. # # Reported-by: Meelis Roos <mroos@linux.ee> # Reported-by: Mathieu Malaterre <malat@debian.org> # Cc: stable@vger.kernel.org # Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> # < /opt/cross/kisskb/gcc-4.6.3-nolibc/powerpc-linux/bin/powerpc-linux-gcc --version # < /opt/cross/kisskb/gcc-4.6.3-nolibc/powerpc-linux/bin/powerpc-linux-ld --version # < git log --format=%s --max-count=1 bc13f05ffaf016d42536571c2e9173f85cefd47a # < make -s -j 24 ARCH=powerpc O=/kisskb/build/powerpc-next_powerpc-allnoconfig_powerpc-gcc4.6 CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/powerpc-linux/bin/powerpc-linux- allnoconfig # make -s -j 24 ARCH=powerpc O=/kisskb/build/powerpc-next_powerpc-allnoconfig_powerpc-gcc4.6 CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/powerpc-linux/bin/powerpc-linux- /kisskb/src/kernel/printk/printk.c: In function 'devkmsg_sysctl_set_loglvl': /kisskb/src/kernel/printk/printk.c:186:16: warning: 'old' may be used uninitialized in this function [-Wuninitialized] Completed OK # rm -rf /kisskb/build/powerpc-next_powerpc-allnoconfig_powerpc-gcc4.6 # Build took: 0:00:11.024647

© Michael Ellerman 2006-2018.