On Fri, 13 Jun 2014 08:56:50 -0700 Josh Triplett <josh@xxxxxxxxxxxxxxxx> wrote: > On Fri, Jun 13, 2014 at 08:05:37AM -0400, Jeff Layton wrote: > > On Thu, 12 Jun 2014 18:06:25 +1000 > > Vitaly Osipov <vitaly.osipov@xxxxxxxxx> wrote: > > > > > Nothing shows up for me on x86_64, allmodconfig, linux-next from 10 of > > > June. My sparse has been compiled from sources. > > > > > > $ make fs/locks.o C=2 CHECK="/home/vosipov/bin/sparse" > > > CHK include/config/kernel.release > > > CHK include/generated/uapi/linux/version.h > > > CHK include/generated/utsrelease.h > > > CALL scripts/checksyscalls.sh > > > CHECK scripts/mod/empty.c > > > CHECK fs/locks.c > > > > > > $ sparse —version > > > v0.5.0 > > > > > > $ which sparse > > > /home/vosipov/bin/sparse > > > > > > Regards, > > > Vitaly > > > > > > > > > On Wed, Jun 11, 2014 at 11:51 PM, Jeff Layton <jlayton@xxxxxxxxxxxxxxx> wrote: > > > > On Wed, 11 Jun 2014 16:11:46 +0300 > > > > Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote: > > > > > > > >> On Wed, Jun 11, 2014 at 07:06:32AM -0400, Jeff Layton wrote: > > > >> > $ rpm -q sparse > > > >> > sparse-0.5.0-1.fc20.x86_64 > > > >> > > > > >> > I see it all over the tree, but an easy example is fs/locks.c: > > > >> > > > > >> > $ make fs/locks.o C=1 > > > >> > make[1]: Nothing to be done for `all'. > > > >> > make[1]: Nothing to be done for `relocs'. > > > >> > CHK include/config/kernel.release > > > >> > CHK include/generated/uapi/linux/version.h > > > >> > CHK include/generated/utsrelease.h > > > >> > CALL scripts/checksyscalls.sh > > > >> > CHECK fs/locks.c > > > >> > include/linux/err.h:35:16: warning: dereference of noderef expression > > > >> > include/linux/err.h:30:23: warning: dereference of noderef expression > > > >> > include/linux/err.h:35:16: warning: dereference of noderef expression > > > >> > include/linux/err.h:30:23: warning: dereference of noderef expression > > > >> > CC fs/locks.o > > > >> > > > > >> > It has two IS_ERR calls and two PTR_ERR calls, and each generates the > > > >> > warning. > > > >> > > > > >> > > > >> I downloaded the Fedora SRPM and built the binary but I still wasn't > > > >> able to reproduce the bug. > > > >> > > > >> dcarpenter@speke:~/progs/kernel/devel$ /tmp/sparse/sparse-0.5.0/sparse --version > > > >> 0.5.0 > > > >> dcarpenter@speke:~/progs/kernel/devel$ make C=2 CHECK=/tmp/sparse/sparse-0.5.0/sparse fs/locks.o > > > >> CHK include/config/kernel.release > > > >> CHK include/generated/uapi/linux/version.h > > > >> CHK include/generated/utsrelease.h > > > >> CALL scripts/checksyscalls.sh > > > >> <stdin>:1226:2: warning: #warning syscall finit_module not implemented [-Wcpp] > > > >> <stdin>:1229:2: warning: #warning syscall sched_setattr not implemented [-Wcpp] > > > >> <stdin>:1232:2: warning: #warning syscall sched_getattr not implemented [-Wcpp] > > > >> <stdin>:1235:2: warning: #warning syscall renameat2 not implemented [-Wcpp] > > > >> CHECK scripts/mod/empty.c > > > >> CHECK fs/locks.c > > > >> dcarpenter@speke:~/progs/kernel/devel$ > > > >> > > > >> I'm on today's linux-next. I can't think of a kernel configuration > > > >> issue which would cause this... > > > >> > > > >> regards, > > > >> dan carpenter > > > > > > > > Could it be arch-specific then? What arch are you using? I'm on x86_64. > > > > I know that quite a few other people have mentioned seeing these > > > > warnings as well, so I'm pretty sure it's not just me. > > > > > > > > Ha! It turns out that my hand-built sparse also works fine, so the > > problem seems to be in the Fedora package. > > > > With a little trial-and-error, I figured out what's causing the > > problem, but I'm a little baffled as to why it's occurring. > > > > The Fedora SRPM builds the program with -fpic. When I remove that flag, > > this problem goes away. I'd appreciate any insight into why that would > > break things. I doubt PIC really makes much difference security-wise in > > sparse, so removing it shouldn't matter much, but I wonder if this > > indicates an underlying bug in sparse itself? > > Wow, that's horrifying. I wonder if it might indicate a miscompilation > by GCC. Does the problem persist if you build with -fpic -g? If so, > you could set a few breakpoints and try to determine at what point the > behavior of the two sparse binaries diverges. > Yeah, this is a bit disturbing. Fedora already builds with -g, so yes, the problem does persist. I made a very small, simple C file that just calls IS_ERR to test with. Broken sparse (built with -fpic): Breakpoint 1, expand_dereference (expr=0x7ffff6f12210) at expand.c:629 629 if (expr->ctype->ctype.modifiers & MOD_NODEREF) (gdb) p expr->ctype->ctype.modifiers $3 = 0x65686374616d6e75 Built w/o -fpic at the same breakpoint: Breakpoint 1, expand_dereference (expr=0x7ffff5e61bd0) at expand.c:629 629 if (expr->ctype->ctype.modifiers & MOD_NODEREF) (gdb) p expr->ctype->ctype.modifiers $2 = 0x0 The stack at that point is: (gdb) bt #0 expand_dereference (expr=0x7ffff5e61bd0) at expand.c:629 #1 expand_preop (expr=0x7ffff5e61bd0) at expand.c:736 #2 expand_expression (expr=expr@entry=0x7ffff5e61bd0) at expand.c:984 #3 0x000000000041217a in expand_cast (expr=0x7ffff5e61c50) at expand.c:777 #4 expand_expression (expr=expr@entry=0x7ffff5e61c50) at expand.c:992 #5 0x00000000004123e2 in expand_compare (expr=0x7ffff5e61cd0) at expand.c:514 #6 expand_expression (expr=<optimized out>) at expand.c:978 #7 0x00000000004127ba in expand_preop (expr=0x7ffff5e61d10) at expand.c:752 #8 expand_expression (expr=<optimized out>) at expand.c:984 #9 0x00000000004127ba in expand_preop (expr=0x7ffff5e61d50) at expand.c:752 #10 expand_expression (expr=<optimized out>) at expand.c:984 #11 0x0000000000412364 in expand_arguments (head=0x7ffff5e39810) at expand.c:767 #12 expand_call (expr=0x7ffff5e61b90) at expand.c:832 #13 expand_expression (expr=expr@entry=0x7ffff5e61b90) at expand.c:995 #14 0x000000000041217a in expand_cast (expr=0x7ffff5e61e10) at expand.c:777 #15 expand_expression (expr=<optimized out>) at expand.c:992 #16 0x0000000000411c75 in expand_statement (stmt=stmt@entry=0x7ffff5fe3920) at expand.c:1202 #17 0x0000000000411e13 in expand_compound (stmt=0x7ffff5fe38d0) at expand.c:1133 #18 expand_statement (stmt=stmt@entry=0x7ffff5fe38d0) at expand.c:1164 #19 0x00000000004124ec in expand_expression (expr=<optimized out>) at expand.c:1007 #20 0x0000000000411dad in expand_statement (stmt=stmt@entry=0x7ffff5fe3880) at expand.c:1161 #21 0x0000000000411e13 in expand_compound (stmt=0x7ffff5fe3830) at expand.c:1133 #22 expand_statement (stmt=0x7ffff5fe3830) at expand.c:1164 #23 0x0000000000411c21 in expand_symbol (sym=sym@entry=0x7ffff5e312d0) at expand.c:1068 #24 0x0000000000401675 in check_symbols (list=0x7ffff6a63610) at sparse.c:281 #25 0x0000000000401208 in main (argc=<optimized out>, argv=<optimized out>) at sparse.c:300 ...so something is corrupting the modifiers field at least and maybe the whole ctype itself? I don't know the sparse code that well, so I'll need to do some more digging to determine the root cause. -- Jeff Layton <jlayton@xxxxxxxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-sparse" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
