Date: Fri, 28 Oct 2016 16:02:26 -0700 From: Mark Millard <markmi@dsl-only.net> To: John Baldwin <jhb@freebsd.org> Cc: freebsd-current@freebsd.org, freebsd-arm <freebsd-arm@freebsd.org>, FreeBSD-STABLE Mailing List <freebsd-stable@freebsd.org>, FreeBSD Toolchain <freebsd-toolchain@freebsd.org> Subject: Re: stable/11 -r307797 on BPi-M3 (cortex-a7): truss gets segmentation fault for handling unknown system call Message-ID: <C3B549C5-AF5B-458C-961D-9C45C63218F5@dsl-only.net> In-Reply-To: <2661167.K5IN9JAPmQ@ralph.baldwin.cx> References: <0699F744-DEB3-4ED5-91A9-B77EA2ACED37@dsl-only.net> <2661167.K5IN9JAPmQ@ralph.baldwin.cx>
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On 2016-Oct-28, at 7:29 AM, John Baldwin <jhb at freebsd.org> wrote: > On Tuesday, October 25, 2016 11:40:38 AM Mark Millard wrote: >> [The following has been reported in: = https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D213778 .] >>=20 >> In trying to build lang/gcc6 xgcc's cc1 got some SIGSYS examples. In = trying to track things down I ran into truss getting a SIGSEGV when it = tries to handle the situation. . . >>=20 >> In truss's enter_syscall there is (from a live gdb on truss, after = the segmentation fault): >>=20 >> 380 t->cs.name =3D sysdecode_syscallname(t->proc->abi->abi, = t->cs.number); >> 381 if (t->cs.name =3D=3D NULL) >> (gdb)=20 >> 382 fprintf(info->outfile, "-- UNKNOWN %s SYSCALL %d = --\n", >> 383 t->proc->abi->type, t->cs.number); >> 384=09 >> 385 sc =3D get_syscall(t->cs.name, narg); >> 386 t->cs.nargs =3D sc->nargs; >> 387 assert(sc->nargs <=3D nitems(t->cs.s_args)); >> 388=09 >> 389 t->cs.sc =3D sc; >>=20 >> (gdb) print *t >> $2 =3D {entries =3D {le_next =3D 0x0, le_prev =3D 0x20617070}, proc =3D= 0x20617060, tid =3D 100150, in_syscall =3D 1, cs =3D {sc =3D 0x0, name = =3D 0x0, number =3D 580828064, args =3D 0x2061b0c0, nargs =3D 0,=20 >> s_args =3D 0x2061b0ec}, before =3D {tv_sec =3D 1477418265, tv_nsec = =3D 492342263}, after =3D {tv_sec =3D 1477418265, tv_nsec =3D = 492496630}} >>=20 >> (gdb) print sc >> $3 =3D (struct syscall *) 0x0 >>=20 >> So line 386 listed above gets a segmentation fault for sc->nargs when = t->cs.name is a NULL pointer: sc ends up NULL. >>=20 >> Looking at the two things that the fprintf on lines 382 and 383 would = report: >>=20 >> (gdb) print t->proc->abi->type >> $4 =3D 0x10166 "FreeBSD ELF32" >>=20 >> (gdb) print t->cs.number >> $5 =3D 580828064 >>=20 >> (gdb) print narg >> $6 =3D 0 >>=20 >> (that last is for context for the get_syscall arguments). >>=20 >> FYI: 580828064 =3D 0x229EBBA0 >=20 > I have a patchset I have tested some in a git branch that I believe = fixes handling of > unknown system calls. Please try this: >=20 > = https://github.com/freebsd/freebsd/compare/master...bsdjhb:truss_unknown >=20 > (Add .diff to get a diff you can apply with patch) >=20 > --=20 > John Baldwin Sorry it took so long to try the build. . . I got a compile failure for use of bool in my stable/11 context for the = BPI-M3 build that the truss problem was discovered with (quoting the = build log below): > --- main.o --- > cc -target armv6-gnueabihf-freebsd11.0 = --sysroot=3D/usr/local/src/crochet/work/obj/arm.armv6/usr/src/tmp = -B/usr/local/src/crochet/work/obj/arm.armv6/usr/src/tmp/usr/bin -O -pipe = -I/usr/src/usr.bin/truss -I. -I/usr/src/usr.bin/truss/../../sys -g -MD = -MF.depend.main.o -MTma > in.o -std=3Dgnu99 -Wsystem-headers -Wall -Wno-format-y2k -W = -Wno-unused-parameter -Wstrict-prototypes -Wmissing-prototypes = -Wpointer-arith -Wreturn-type -Wcast-qual -Wwrite-strings -Wswitch = -Wshadow -Wunused-parameter -Wcast-align -Wchar-subscripts -Winline = -Wnested-externs=20 > -Wredundant-decls -Wold-style-definition -Wno-pointer-sign = -Wmissing-variable-declarations -Wthread-safety -Wno-empty-body = -Wno-string-plus-int -Wno-unused-const-variable -Qunused-arguments -c = /usr/src/usr.bin/truss/main.c -o main.o > In file included from /usr/src/usr.bin/truss/main.c:53: > /usr/src/usr.bin/truss/syscall.h:75:2: error: unknown type name 'bool' > bool unknown; /* Uknown system call */ > ^ > 1 error generated. > *** [main.o] Error code 1 >=20 > make[4]: stopped in /usr/src/usr.bin/truss > 1 error In C99 bool is a macro from <stdbool.h> and _Bool is the C99 type = itself. So apparently <stdbool.h> (or an equivalent) was not directly or = indirectly included. (The macros true and false and = __bool_true_false_are_defined are also from <stdbool.h> .) Which way do you want the C99 typing to be handled for this: native C99 = with no <stdbool.h> required? Use <stdbool.h> ? Side note: I'll see about getting my normal stable/11 build environment going for = the BPI-M3 instead of using the crochet from my first-time build for the = target. =3D=3D=3D Mark Millard markmi at dsl-only.net
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