[sanitizer] Don't use ARM_VFPREGS_SIZE for old kernels.

[m.ostapenko]

Summary

Hi,

after recent sanitzer library merge to GCC we have noticed, that for older kernel versions ARM_VFPREGS_SIZE is not defined that leads to such error on arm-none-linux-gnueabi:

libtool: compile:
/tmp/1800227_1.tmpdir/aci-gcc-fsf/builds/gcc-fsf-gccsrc/obj-arm-none-linux-gnueabi/gcc3/./gcc/xgcc
-shared-libgcc -B/tmp/1800227_1.tmpdir/aci-gcc-fsf/builds/g
cc-fsf-gccsrc/obj-arm-none-linux-gnueabi/gcc3/./gcc -nostdinc++
-L/tmp/1800227_1.tmpdir/aci-gcc-fsf/builds/gcc-fsf-gccsrc/obj-arm-none-linux-gnueabi/gcc3/arm-none-linux-gnueabi/
libstdc++-v3/src
-L/tmp/1800227_1.tmpdir/aci-gcc-fsf/builds/gcc-fsf-gccsrc/obj-arm-none-linux-gnueabi/gcc3/arm-none-linux-gnueabi/libstdc++-v3/src/.libs
-L/tmp/1800227_1.tmpdir/
aci-gcc-fsf/builds/gcc-fsf-gccsrc/obj-arm-none-linux-gnueabi/gcc3/arm-none-linux-gnueabi/libstdc++-v3/libsupc++/.libs
-B/tmp/1800227_1.tmpdir/aci-gcc-fsf/builds/gcc-fsf-gccsrc/t
ools/arm-none-linux-gnueabi/bin/
-B/tmp/1800227_1.tmpdir/aci-gcc-fsf/builds/gcc-fsf-gccsrc/tools/arm-none-linux-gnueabi/lib/
-isystem /tmp/1800227_1.tmpdir/aci-gcc-fsf/builds/gc
c-fsf-gccsrc/tools/arm-none-linux-gnueabi/include -isystem
/tmp/1800227_1.tmpdir/aci-gcc-fsf/builds/gcc-fsf-gccsrc/tools/arm-none-linux-gnueabi/sys-include
-D_GNU_SOURCE -D_DEBU
G -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS
-D__STDC_LIMIT_MACROS -DHAVE_RPC_XDR_H=1 -DHAVE_TIRPC_RPC_XDR_H=0 -I.
-I/tmp/1800227_1.tmpdir/aci-gcc-fsf/sources/gcc-fsf/gccsr
c/libsanitizer/sanitizer_common -I.. -I
/tmp/1800227_1.tmpdir/aci-gcc-fsf/sources/gcc-fsf/gccsrc/libsanitizer/include
-isystem /tmp/1800227_1.tmpdir/aci-gcc-fsf/sources/gcc-fsf/
gccsrc/libsanitizer/include/system -Wall -W -Wno-unused-parameter
-Wwrite-strings -pedantic -Wno-long-long -fPIC -fno-builtin
-fno-exceptions -fno-rtti -fomit-frame-pointer -fun
wind-tables -fvisibility=hidden -Wno-variadic-macros
-I../../libstdc++-v3/include
-I../../libstdc++-v3/include/arm-none-linux-gnueabi
-I/tmp/1800227_1.tmpdir/aci-gcc-fsf/sources
/gcc-fsf/gccsrc/libsanitizer/../libstdc++-v3/libsupc++ -std=gnu++11
-DSANITIZER_LIBBACKTRACE -DSANITIZER_CP_DEMANGLE -I
/tmp/1800227_1.tmpdir/aci-gcc-fsf/sources/gcc-fsf/gccsrc/
libsanitizer/../libbacktrace -I ../libbacktrace -I
/tmp/1800227_1.tmpdir/aci-gcc-fsf/sources/gcc-fsf/gccsrc/libsanitizer/../include
-include /tmp/1800227_1.tmpdir/aci-gcc-fsf/so
urces/gcc-fsf/gccsrc/libsanitizer/libbacktrace/backtrace-rename.h -g
-O2 -D_GNU_SOURCE -MT sanitizer_platform_limits_posix.lo -MD -MP -MF
.deps/sanitizer_platform_limits_posix.T
po -c /tmp/1800227_1.tmpdir/aci-gcc-fsf/sources/gcc-fsf/gccsrc/libsanitizer/sanitizer_common/sanitizer_platform_limits_posix.cc
 -fPIC -DPIC -o .libs/sanitizer_platform_limits_p
osix.o
/tmp/1800227_1.tmpdir/aci-gcc-fsf/sources/gcc-fsf/gccsrc/libsanitizer/sanitizer_common/sanitizer_platform_limits_posix.cc:326:44:
error: 'ARM_VFPREGS_SIZE' was not declared in t
his scope
   unsigned struct_user_vfpregs_struct_sz = ARM_VFPREGS_SIZE;
                                            ^~~~~~~~~~~~~~~~

make[4]: *** [sanitizer_platform_limits_posix.lo] Error 1

After some investigation, I found out that ptrace_getvfpregs and ptrace_setvfpregs have a guard against such an issue:

   int ptrace_getfpxregs = -1;
   int ptrace_setfpxregs = -1;
 #endif // PTRACE_GETFPXREGS/PTRACE_SETFPXREGS
+#if defined(PTRACE_GETVFPREGS) && defined(PTRACE_SETVFPREGS)
+  int ptrace_getvfpregs = PTRACE_GETVFPREGS;
+  int ptrace_setvfpregs = PTRACE_SETVFPREGS;
+#else
+  int ptrace_getvfpregs = -1;
+  int ptrace_setvfpregs = -1;
+#endif

Perhaps we could do the same thing for ARM_VFPREGS_SIZE?

[m.ostapenko]

Ugh, just noticed, that PTRACE_SETVFPREGS and PTRACE_GETVFPREGS were introduced in Linux 2.6.30 and ARM_VFPREGS_SIZE only in 3.0. So, struct_user_vfpregs_struct_sz = 0 is not safe for 2.6.30 - 2.6.39. Fix by defining ARM_VFPREGS_SIZE as 32 * 8 /*fpregs*/ + 4 /*fpscr*/ for these kernels.

[ygribov]

lib/sanitizer_common/sanitizer_platform_limits_posix.cc

127 ↗

(On Diff #40928)

Perhaps also assert equality in #else branch?

[emaste]

In the eventual commit message please make sure to indicate which kernel you're referring to (i.e., Linux), since this file is used on FreeBSD as well.

[m.ostapenko]

lib/sanitizer_common/sanitizer_platform_limits_posix.cc

127 ↗

(On Diff #40928)

I can do it, but I'll need to move ARM_VFPREGS_SIZE definition down in source code to be able use ASan internal checks (such as COMPILER_CHECK), perhaps just before its usage. Is it OK?

[m.ostapenko]

Addressing Yura's comment.

[samsonov]

I'll let ARM folks comment, but looks reasonable.

[zatrazz]

LGTM.

[m.ostapenko]

Thanks! Will commit this soon if no objections.

compiler-rt/trunk/lib/sanitizer_common/sanitizer_platform_limits_posix.cc

 
 #if SANITIZER_LINUX || SANITIZER_FREEBSD
 # include <utime.h>
 # include <sys/ptrace.h>
 # if defined(__mips64) || defined(__aarch64__) || defined(__arm__)
 #  include <asm/ptrace.h>
 #  ifdef __arm__
 typedef struct user_fpregs elf_fpregset_t;
+#   define ARM_VFPREGS_SIZE_ASAN (32 * 8 /*fpregs*/ + 4 /*fpscr*/)
+#   if !defined(ARM_VFPREGS_SIZE)
+#     define ARM_VFPREGS_SIZE ARM_VFPREGS_SIZE_ASAN
+#   endif
 #  endif
 # endif
 # include <semaphore.h>
 #endif
 
 #if !SANITIZER_ANDROID
 #include <ifaddrs.h>
 #include <sys/ucontext.h>

 CHECK_SIZE_AND_OFFSET(cookie_io_functions_t, seek);
 CHECK_SIZE_AND_OFFSET(cookie_io_functions_t, close);
 #endif
 
 #if SANITIZER_LINUX || SANITIZER_FREEBSD
 CHECK_TYPE_SIZE(sem_t);
 #endif
 
+#if SANITIZER_LINUX && defined(__arm__)
+COMPILER_CHECK(ARM_VFPREGS_SIZE == ARM_VFPREGS_SIZE_ASAN);
+#endif
+
 #endif // SANITIZER_LINUX || SANITIZER_FREEBSD || SANITIZER_MAC