# git rev-parse -q --verify aee101d7b95a03078945681dd7f7ea5e4a1e7686^{commit}
aee101d7b95a03078945681dd7f7ea5e4a1e7686
already have revision, skipping fetch
# git checkout -q -f -B kisskb aee101d7b95a03078945681dd7f7ea5e4a1e7686
# git clean -qxdf
# < git log -1
# commit aee101d7b95a03078945681dd7f7ea5e4a1e7686
# Author: Nicholas Piggin <npiggin@gmail.com>
# Date:   Mon Jan 17 23:44:03 2022 +1000
# 
#     powerpc/64s: Mask SRR0 before checking against the masked NIP
#     
#     Commit 314f6c23dd8d ("powerpc/64s: Mask NIP before checking against
#     SRR0") masked off the low 2 bits of the NIP value in the interrupt
#     stack frame in case they are non-zero and mis-compare against a SRR0
#     register value of a CPU which always reads back 0 from the 2 low bits
#     which are reserved.
#     
#     This now causes the opposite problem that an implementation which does
#     implement those bits in SRR0 will mis-compare against the masked NIP
#     value in which they have been cleared. QEMU is one such implementation,
#     and this is allowed by the architecture.
#     
#     This can be triggered by sigfuz by setting low bits of PT_NIP in the
#     signal context.
#     
#     Fix this for now by masking the SRR0 bits as well. Cleaner is probably
#     to sanitise these values before putting them in registers or stack, but
#     this is the quick and backportable fix.
#     
#     Fixes: 314f6c23dd8d ("powerpc/64s: Mask NIP before checking against SRR0")
#     Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
#     Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
#     Link: https://lore.kernel.org/r/20220117134403.2995059-1-npiggin@gmail.com
# < /opt/cross/kisskb/korg/gcc-11.1.0-nolibc/x86_64-linux/bin/x86_64-linux-gcc --version
# < /opt/cross/kisskb/korg/gcc-11.1.0-nolibc/x86_64-linux/bin/x86_64-linux-ld --version
# < git log --format=%s --max-count=1 aee101d7b95a03078945681dd7f7ea5e4a1e7686
# < make -s -j 48 ARCH=x86 O=/kisskb/build/powerpc-fixes_x86-allmodconfig_x86_64-gcc11 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-11.1.0-nolibc/x86_64-linux/bin/x86_64-linux-  allmodconfig
# Added to kconfig CONFIG_BUILD_DOCSRC=n
# Added to kconfig CONFIG_MODULE_SIG=n
# Added to kconfig CONFIG_SAMPLES=n
# < make -s -j 48 ARCH=x86 O=/kisskb/build/powerpc-fixes_x86-allmodconfig_x86_64-gcc11 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-11.1.0-nolibc/x86_64-linux/bin/x86_64-linux-  help
# make -s -j 48 ARCH=x86 O=/kisskb/build/powerpc-fixes_x86-allmodconfig_x86_64-gcc11 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-11.1.0-nolibc/x86_64-linux/bin/x86_64-linux-  olddefconfig
# make -s -j 48 ARCH=x86 O=/kisskb/build/powerpc-fixes_x86-allmodconfig_x86_64-gcc11 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-11.1.0-nolibc/x86_64-linux/bin/x86_64-linux-  
vmlinux.o: warning: objtool: __do_fast_syscall_32()+0xa: call to stackleak_track_stack() leaves .noinstr.text section
vmlinux.o: warning: objtool: do_syscall_64()+0x9: call to stackleak_track_stack() leaves .noinstr.text section
vmlinux.o: warning: objtool: do_int80_syscall_32()+0x9: call to stackleak_track_stack() leaves .noinstr.text section
vmlinux.o: warning: objtool: exc_general_protection()+0x22: call to stackleak_track_stack() leaves .noinstr.text section
vmlinux.o: warning: objtool: fixup_bad_iret()+0x20: call to stackleak_track_stack() leaves .noinstr.text section
vmlinux.o: warning: objtool: mce_start()+0x5c: call to __kasan_check_write() leaves .noinstr.text section
vmlinux.o: warning: objtool: mce_gather_info()+0x5f: call to v8086_mode.constprop.0() leaves .noinstr.text section
vmlinux.o: warning: objtool: mce_read_aux()+0x8a: call to mca_msr_reg() leaves .noinstr.text section
vmlinux.o: warning: objtool: do_machine_check()+0x27: call to stackleak_track_stack() leaves .noinstr.text section
vmlinux.o: warning: objtool: mce_severity_amd.constprop.0()+0xca: call to mce_severity_amd_smca() leaves .noinstr.text section
vmlinux.o: warning: objtool: .text+0x5332e: call to stackleak_erase() leaves .noinstr.text section
vmlinux.o: warning: objtool: .entry.text+0x143: call to stackleak_erase() leaves .noinstr.text section
vmlinux.o: warning: objtool: .entry.text+0x10eb: call to stackleak_erase() leaves .noinstr.text section
vmlinux.o: warning: objtool: .entry.text+0x17f9: call to stackleak_erase() leaves .noinstr.text section
Completed OK
# rm -rf /kisskb/build/powerpc-fixes_x86-allmodconfig_x86_64-gcc11
# Build took: 0:33:12.633818