# git rev-parse -q --verify e376ca093587eafd840bb0f9df04090e2a54249c^{commit}
# git fetch -q -n -f git://gitlab.ozlabs.ibm.com/linuxppc/linux.git next-test
warning: The last gc run reported the following. Please correct the root cause
and remove .git/gc.log.
Automatic cleanup will not be performed until the file is removed.

warning: There are too many unreachable loose objects; run 'git prune' to remove them.

# git rev-parse -q --verify e376ca093587eafd840bb0f9df04090e2a54249c^{commit}
e376ca093587eafd840bb0f9df04090e2a54249c
# git checkout -q -f -B kisskb e376ca093587eafd840bb0f9df04090e2a54249c
# git clean -qxdf
# < git log -1
# commit e376ca093587eafd840bb0f9df04090e2a54249c
# Author: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
# Date:   Tue Apr 21 23:05:45 2020 +0530
# 
#     powerpc/module_64: Use special stub for _mcount() with -mprofile-kernel
#     
#     Since commit c55d7b5e64265f ("powerpc: Remove STRICT_KERNEL_RWX
#     incompatibility with RELOCATABLE"), powerpc kernels with
#     -mprofile-kernel can crash in certain scenarios with a trace like below:
#     
#         BUG: Unable to handle kernel instruction fetch (NULL pointer?)
#         Faulting instruction address: 0x00000000
#         Oops: Kernel access of bad area, sig: 11 [#1]
#         LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=256 DEBUG_PAGEALLOC NUMA PowerNV
#         <snip>
#         NIP [0000000000000000] 0x0
#         LR [c0080000102c0048] ext4_iomap_end+0x8/0x30 [ext4]
#         Call Trace:
#          iomap_apply+0x20c/0x920 (unreliable)
#          iomap_bmap+0xfc/0x160
#          ext4_bmap+0xa4/0x180 [ext4]
#          bmap+0x4c/0x80
#          jbd2_journal_init_inode+0x44/0x1a0 [jbd2]
#          ext4_load_journal+0x440/0x860 [ext4]
#          ext4_fill_super+0x342c/0x3ab0 [ext4]
#          mount_bdev+0x25c/0x290
#          ext4_mount+0x28/0x50 [ext4]
#          legacy_get_tree+0x4c/0xb0
#          vfs_get_tree+0x4c/0x130
#          do_mount+0xa18/0xc50
#          sys_mount+0x158/0x180
#          system_call+0x5c/0x68
#     
#     The NIP points to NULL, or a random location (data even), while the LR
#     always points to the LEP of a function (with an offset of 8), indicating
#     that something went wrong with ftrace. However, ftrace is not
#     necessarily active when such crashes occur.
#     
#     The kernel OOPS sometimes follows a warning from ftrace indicating that
#     some module functions could not be patched with a nop. Other times, if a
#     module is loaded early during boot, instruction patching can fail due to
#     a separate bug, but the error is not reported due to missing error
#     reporting.
#     
#     In all the above cases when instruction patching fails, ftrace will be
#     disabled but certain kernel module functions will be left with default
#     calls to _mcount(). This is not a problem with ELFv1. However, with
#     -mprofile-kernel, the default stub is problematic since it depends on a
#     valid module TOC in r2. If the kernel (or a different module) calls into
#     a function that does not use the TOC, the function won't have a prologue
#     to setup the module TOC. When that function calls into _mcount(), we
#     will end up in the relocation stub that will use the previous TOC, and
#     end up trying to jump into a random location. From the above trace:
#     
#             iomap_apply+0x20c/0x920 [kernel TOC]
#                             |
#                             V
#             ext4_iomap_end+0x8/0x30 [no GEP == kernel TOC]
#                             |
#                             V
#                     _mcount() stub
#             [uses kernel TOC -> random entry]
#     
#     To address this, let's change over to using the special stub that is
#     used for ftrace_[regs_]caller() for _mcount(). This ensures that we are
#     not dependent on a valid module TOC in r2 for default _mcount()
#     handling.
#     
#     Reported-by: Qian Cai <cai@lca.pw>
#     Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
#     Tested-by: Qian Cai <cai@lca.pw>
#     Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
#     Link: https://lore.kernel.org/r/8affd4298d22099bbd82544fab8185700a6222b1.1587488954.git.naveen.n.rao@linux.vnet.ibm.com
# < /opt/cross/kisskb/korg/gcc-8.1.0-nolibc/m68k-linux/bin/m68k-linux-gcc --version
# < /opt/cross/kisskb/korg/gcc-8.1.0-nolibc/m68k-linux/bin/m68k-linux-ld --version
# < git log --format=%s --max-count=1 e376ca093587eafd840bb0f9df04090e2a54249c
# < make -s -j 48 ARCH=m68k O=/kisskb/build/powerpc-next_m68k-defconfig_m68k-gcc8 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.1.0-nolibc/m68k-linux/bin/m68k-linux-  defconfig
# < make -s -j 48 ARCH=m68k O=/kisskb/build/powerpc-next_m68k-defconfig_m68k-gcc8 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.1.0-nolibc/m68k-linux/bin/m68k-linux-  help
# make -s -j 48 ARCH=m68k O=/kisskb/build/powerpc-next_m68k-defconfig_m68k-gcc8 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.1.0-nolibc/m68k-linux/bin/m68k-linux-  olddefconfig
# make -s -j 48 ARCH=m68k O=/kisskb/build/powerpc-next_m68k-defconfig_m68k-gcc8 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.1.0-nolibc/m68k-linux/bin/m68k-linux-  
In file included from /kisskb/src/arch/m68k/include/asm/amigayle.h:21,
                 from /kisskb/src/arch/m68k/include/asm/io_mm.h:59,
                 from /kisskb/src/arch/m68k/include/asm/io.h:8,
                 from /kisskb/src/include/linux/clocksource.h:21,
                 from /kisskb/src/arch/m68k/amiga/config.c:20:
/kisskb/src/arch/m68k/amiga/config.c: In function 'amiga_identify':
/kisskb/src/arch/m68k/include/asm/amigahw.h:42:50: warning: this statement may fall through [-Wimplicit-fallthrough=]
 #define AMIGAHW_SET(name) (amiga_hw_present.name = 1)
                           ~~~~~~~~~~~~~~~~~~~~~~~^~~~
/kisskb/src/arch/m68k/amiga/config.c:223:3: note: in expansion of macro 'AMIGAHW_SET'
   AMIGAHW_SET(PCMCIA);
   ^~~~~~~~~~~
/kisskb/src/arch/m68k/amiga/config.c:224:2: note: here
  case AMI_500:
  ^~~~
/kisskb/src/arch/m68k/mvme147/config.c: In function 'mvme147_hwclk':
/kisskb/src/arch/m68k/mvme147/config.c:175:2: warning: #warning check me! [-Wcpp]
 #warning check me!
  ^~~~~~~
/kisskb/src/arch/m68k/mvme16x/config.c: In function 'mvme16x_hwclk':
/kisskb/src/arch/m68k/mvme16x/config.c:440:2: warning: #warning check me! [-Wcpp]
 #warning check me!
  ^~~~~~~
In file included from /kisskb/src/arch/m68k/include/asm/atomic.h:7,
                 from /kisskb/src/include/linux/atomic.h:7,
                 from /kisskb/src/include/linux/spinlock.h:460,
                 from /kisskb/src/include/linux/seqlock.h:36,
                 from /kisskb/src/include/linux/time.h:6,
                 from /kisskb/src/include/linux/stat.h:19,
                 from /kisskb/src/include/linux/module.h:13,
                 from /kisskb/src/net/core/filter.c:20:
/kisskb/src/net/core/filter.c: In function 'bpf_clear_redirect_map':
/kisskb/src/arch/m68k/include/asm/cmpxchg.h:137:3: warning: value computed is not used [-Wunused-value]
  ((__typeof__(*(ptr)))__cmpxchg_local_generic((ptr), (unsigned long)(o),\
  ~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    (unsigned long)(n), sizeof(*(ptr))))
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/kisskb/src/include/asm-generic/cmpxchg.h:106:28: note: in expansion of macro 'cmpxchg_local'
 #define cmpxchg(ptr, o, n) cmpxchg_local((ptr), (o), (n))
                            ^~~~~~~~~~~~~
/kisskb/src/net/core/filter.c:3529:4: note: in expansion of macro 'cmpxchg'
    cmpxchg(&ri->map, map, NULL);
    ^~~~~~~
In file included from /kisskb/src/arch/m68k/include/asm/atomic.h:7,
                 from /kisskb/src/include/linux/atomic.h:7,
                 from /kisskb/src/include/linux/spinlock.h:460,
                 from /kisskb/src/include/linux/mmzone.h:8,
                 from /kisskb/src/include/linux/gfp.h:6,
                 from /kisskb/src/include/linux/mm.h:10,
                 from /kisskb/src/kernel/acct.c:47:
/kisskb/src/kernel/acct.c: In function 'acct_pin_kill':
/kisskb/src/arch/m68k/include/asm/cmpxchg.h:137:3: warning: value computed is not used [-Wunused-value]
  ((__typeof__(*(ptr)))__cmpxchg_local_generic((ptr), (unsigned long)(o),\
  ~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    (unsigned long)(n), sizeof(*(ptr))))
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/kisskb/src/include/asm-generic/cmpxchg.h:106:28: note: in expansion of macro 'cmpxchg_local'
 #define cmpxchg(ptr, o, n) cmpxchg_local((ptr), (o), (n))
                            ^~~~~~~~~~~~~
/kisskb/src/kernel/acct.c:177:2: note: in expansion of macro 'cmpxchg'
  cmpxchg(&acct->ns->bacct, pin, NULL);
  ^~~~~~~
In file included from /kisskb/src/drivers/net/ethernet/8390/xsurf100.c:48:
/kisskb/src/drivers/net/ethernet/8390/lib8390.c:988:27: warning: '____alloc_ei_netdev' defined but not used [-Wunused-function]
 static struct net_device *____alloc_ei_netdev(int size)
                           ^~~~~~~~~~~~~~~~~~~
/kisskb/src/drivers/net/ethernet/8390/lib8390.c:950:13: warning: '__ei_set_multicast_list' defined but not used [-Wunused-function]
 static void __ei_set_multicast_list(struct net_device *dev)
             ^~~~~~~~~~~~~~~~~~~~~~~
/kisskb/src/drivers/net/ethernet/8390/lib8390.c:850:33: warning: '__ei_get_stats' defined but not used [-Wunused-function]
 static struct net_device_stats *__ei_get_stats(struct net_device *dev)
                                 ^~~~~~~~~~~~~~
/kisskb/src/drivers/net/ethernet/8390/lib8390.c:509:13: warning: '__ei_poll' defined but not used [-Wunused-function]
 static void __ei_poll(struct net_device *dev)
             ^~~~~~~~~
/kisskb/src/drivers/net/ethernet/8390/lib8390.c:300:20: warning: '__ei_start_xmit' defined but not used [-Wunused-function]
 static netdev_tx_t __ei_start_xmit(struct sk_buff *skb,
                    ^~~~~~~~~~~~~~~
/kisskb/src/drivers/net/ethernet/8390/lib8390.c:254:13: warning: '__ei_tx_timeout' defined but not used [-Wunused-function]
 static void __ei_tx_timeout(struct net_device *dev, unsigned int txqueue)
             ^~~~~~~~~~~~~~~
/kisskb/src/drivers/net/ethernet/8390/lib8390.c:230:12: warning: '__ei_close' defined but not used [-Wunused-function]
 static int __ei_close(struct net_device *dev)
            ^~~~~~~~~~
/kisskb/src/drivers/net/ethernet/8390/lib8390.c:201:12: warning: '__ei_open' defined but not used [-Wunused-function]
 static int __ei_open(struct net_device *dev)
            ^~~~~~~~~
In file included from /kisskb/src/arch/m68k/include/asm/atomic.h:7,
                 from /kisskb/src/include/linux/atomic.h:7,
                 from /kisskb/src/include/linux/spinlock.h:460,
                 from /kisskb/src/include/linux/wait.h:9,
                 from /kisskb/src/include/linux/wait_bit.h:8,
                 from /kisskb/src/include/linux/fs.h:6,
                 from /kisskb/src/fs/ocfs2/file.c:13:
/kisskb/src/fs/ocfs2/file.c: In function 'ocfs2_file_write_iter':
/kisskb/src/arch/m68k/include/asm/cmpxchg.h:79:22: warning: value computed is not used [-Wunused-value]
 #define xchg(ptr,x) ((__typeof__(*(ptr)))__xchg((unsigned long)(x),(ptr),sizeof(*(ptr))))
                     ~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/kisskb/src/fs/ocfs2/file.c:2419:3: note: in expansion of macro 'xchg'
   xchg(&iocb->ki_complete, saved_ki_complete);
   ^~~~
In file included from /kisskb/src/arch/m68k/include/asm/atomic.h:7,
                 from /kisskb/src/include/linux/atomic.h:7,
                 from /kisskb/src/include/linux/spinlock.h:460,
                 from /kisskb/src/include/linux/mmzone.h:8,
                 from /kisskb/src/include/linux/gfp.h:6,
                 from /kisskb/src/include/linux/slab.h:15,
                 from /kisskb/src/fs/posix_acl.c:15:
/kisskb/src/fs/posix_acl.c: In function 'get_acl':
/kisskb/src/arch/m68k/include/asm/cmpxchg.h:137:3: warning: value computed is not used [-Wunused-value]
  ((__typeof__(*(ptr)))__cmpxchg_local_generic((ptr), (unsigned long)(o),\
  ~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    (unsigned long)(n), sizeof(*(ptr))))
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/kisskb/src/include/asm-generic/cmpxchg.h:106:28: note: in expansion of macro 'cmpxchg_local'
 #define cmpxchg(ptr, o, n) cmpxchg_local((ptr), (o), (n))
                            ^~~~~~~~~~~~~
/kisskb/src/fs/posix_acl.c:148:3: note: in expansion of macro 'cmpxchg'
   cmpxchg(p, sentinel, ACL_NOT_CACHED);
   ^~~~~~~
Completed OK
# rm -rf /kisskb/build/powerpc-next_m68k-defconfig_m68k-gcc8
# Build took: 0:02:09.786651