devel July 2019

devel@uclibc-ng.org

3 participants
4 discussions

by Christoph Mammitzsch

Hi, I was trying to compile a buildroot-2019.02.4 system for an aarch64 platform using gcc 8.3.0 and uClibc-ng-1.0.31. Everything seemed to boot fine, but when I added the ntpd daemon, the daemon kept segfaulting. Some debugging showed, that the segfault happened inside the res_init function, so i made the following test program: ----test_res_init.c---- #include <resolv.h> void main(void) { res_init(); } ----------------------- This program always segfaults as soon as res_init tries to access the _res structure. Some more debugging revealed, that there seems to be a general problem with accessing thread local storage from a dynamicly linked library, so I wrote the following test code: ----test_lib.c---- #include <stdio.h> int ii; __thread int *iip = &ii; void print_ptrs(void) { printf("print_ptrs:\n"); printf("&iip = %p\n", &iip); printf("&ii = %p\n", &ii); printf("iip = %p\n", iip); } ----test_tls.c---- #include <stdio.h> void print_ptrs(void); extern int ii; extern __thread int *iip; void main(void) { printf("main:\n"); printf("&iip = %p\n", &iip); printf("&ii = %p\n", &ii); printf("iip = %p\n", iip); print_ptrs(); } ------------------ When compiling the source linke this: # aarch64-linux-gcc -g -fPIC -c -o test_lib.o test_lib.c # aarch64-linux-gcc -shared -o test_lib.so test_lib.o # aarch64-linux-gcc -g test_tls.c test_lib.so -o test_tls the result looks like this: ------------------------------- # LD_LIBRARY_PATH=/root /root/test_tls main: &iip = 0x7fa0d756d0 &ii = 0x411048 iip = 0x411048 print_ptrs: &iip = 0xff41ac4d90 &ii = 0x411048 [ 7654.009770] test_tls[1942]: unhandled level 0 translation fault (11) at 0xff41ac4d90, esr 0x92000004 [ 7654.018844] pgd = ffffffc07d48c000 [ 7654.027775] [ff41ac4d90] *pgd=0000000000000000 [ 7654.036007] , *pud=0000000000000000 [ 7654.039488] [ 7654.040951] [ 7654.042441] CPU: 2 PID: 1942 Comm: test_tls Not tainted 4.9.0-g196f33d0-dirty #6 [ 7654.049820] Hardware name: xlnx,zynqmp (DT) [ 7654.053981] task: ffffffc05e71ad00 task.stack: ffffffc05d9d4000 [ 7654.059884] PC is at 0x7fa0d4f8f4 [ 7654.063186] LR is at 0x7fa0d4f8ec [ 7654.066478] pc : [<0000007fa0d4f8f4>] lr : [<0000007fa0d4f8ec>] pstate: 60000000 [ 7654.073864] sp : 0000007fe5405170 [ 7654.077148] x29: 0000007fe5405170 x28: 0000000000000000 [ 7654.082442] x27: 0000000000000000 x26: 0000000000000000 [ 7654.087736] x25: 0000000000000000 x24: 0000000000000000 [ 7654.093031] x23: 0000000000000000 x22: 0000000000000000 [ 7654.098326] x21: 0000000000400740 x20: 0000000000000000 [ 7654.103620] x19: 0000000000000000 x18: 0000000000000000 [ 7654.108915] x17: 0000007fa0c8f698 x16: 0000007fa0d60000 [ 7654.114210] x15: 0000000000000001 x14: 0000000000000000 [ 7654.119505] x13: 0000007fa0d77a18 x12: 0000000000000018 [ 7654.124800] x11: 0000000000000001 x10: 0000007fa0d4f517 [ 7654.130095] x9 : 0000007fa0d77a08 x8 : 0000000000000040 [ 7654.135389] x7 : 000000000000000a x6 : 000000000000000a [ 7654.140684] x5 : 0000007fa0d36b6f x4 : 0000007fa0d4f951 [ 7654.145979] x3 : 0000000000000000 x2 : 36bc912578986b49 [ 7654.151274] x1 : 0000007fa0d756c0 x0 : 000000ff41ac4d90 [ 7654.156568] Segmentation fault ------------------------------- Note that the program shows two different addresses for &iip with the latter pointing outside the normal memory map. However the test_tls program works as expected, if you set the LD_BIND_NOW environment variable: ------------------------------- # LD_BIND_NOW=1 LD_LIBRARY_PATH=/root /root/test_tls main: &iip = 0x7f99b606d0 &ii = 0x411048 iip = 0x411048 print_ptrs: &iip = 0x7f99b606d0 &ii = 0x411048 iip = 0x411048 ------------------------------- Unfortunately this trick does not seem to work for either the test_res_init program or the ntpd. Regards, Christoph Mammitzsch

5 years, 4 months

Re: [uclibc-ng-devel] [PATCH 0/1] memmove/memcpy issue on MIPS

by Waldemar Brodkorb

Hi, patch applied and pushed, Waldemar Petar Jovanovic wrote, > Hi All, > > The previous patch to fix generic memmove() was incorrect even though it > fixed issues with the tests. The comments in the memmove() function and > different failing test cases misled me to believe the call to memcopy() > was wrongly conditioned by __ARCH_HAS_BWD_MEMCPY__. It was not. > > This generic memmove implementation assumes that memcpy does forward > copying and that no issues could be seen in this case. However, at least > MIPS arch has an optimized memcpy that uses prefetching and that > implementation does not work correctly for overlapping regions. > > So, my suggestions is that for now we skip memcpy() calls for MIPS, and > if more arches in future come across this, we can unify it (same as it > was done for __ARCH_HAS_BWD_MEMCPY__). > > Sorry for not fixing this correctly in the first patch already. > > Thanks. > > Regards, > Petar > > Petar Jovanovic (1): > mips: avoid calling memcpy() from memmove() for MIPS arch > > libc/string/generic/memmove.c | 10 +++++++--- > 1 file changed, 7 insertions(+), 3 deletions(-) > > -- > 2.17.1 >

5 years, 5 months

[PATCH] Fix header installation for recent 64-only arch

by Yann Sionneau

Summary: Recent arch do not support Legacy. Thus they don't define ARCH_HAS_DEPRECATED_SYSCALLS But this led to per-arch headers not being installed and common-generic ones taking precedence. So it was impossible to declare arch-specific statfs.h for instance, to force 64-bit mode only. This was leading to the following situation to happen: 1/ an application compiles (say without -D_FILE_OFFSET_BITS set) it therefore uses struct statfs from libc/sysdeps/linux/common-generic/bits/statfs.h where f_type and f_bsize fields are U32: https://elixir.bootlin.com/uclibc-ng/latest/source/libc/sysdeps/linux/commo… 2/ application calls "statfs" 3/ uClibc issues "statfs64" syscall (because __NR_statfs64 is defined and __NR_statfs is undefined): https://elixir.bootlin.com/uclibc-ng/latest/source/libc/sysdeps/linux/commo… 4/ if Linux kernel port is not defining CONFIG_COMPAT, it calls do_statfs_native https://elixir.bootlin.com/linux/latest/source/fs/statfs.c#L195 5/ it does copy_to_user of the size of struct statfs defined in the kernel source tree: https://elixir.bootlin.com/linux/latest/source/fs/statfs.c#L161 6/ Generic struct statfs in the kernel is defined like this: https://elixir.bootlin.com/linux/latest/source/include/uapi/asm-generic/sta… f_type and f_bsize fields are long (64 bits) for 64-bit archs. 7/ memory corruption occurs because of this mismatch Solution: Allow to not define __ARCH_HAS_DEPRECATED_SYSCALLS__ *and* declare its own arch-specific statfs.h header, matching the kernel one. (for instance with f_type and f_bsize defined as long) Does this change break other archs? This change allows headers in libc/sysdeps/linux/<ARCH>/bits/ to override ones in libc/sysdeps/linux/common-generic/bits/ The only arch which does not define __ARCH_HAS_DEPRECATED_SYSCALLS__ *and* has a header in libc/sysdeps/linux/<ARCH>/bits/ which can conflict with one in libc/sysdeps/linux/common-generic/bits/ is c6x. The file that can override is ../libc/sysdeps/linux/c6x/bits/kernel_stat.h This, btw, means that, today, this file is there and is not used (during compilation, GNU Make overrides the rule): Makefile.in:152: warning: overriding recipe for target `include/bits/kernel_stat.h' Makefile.in:148: warning: ignoring old recipe for target `include/bits/kernel_stat.h' I was not able to compile uClibc with the only binary toolchain I found for c6x arch (gcc-4.5.1 from code sourcery: https://sourcery.mentor.com/GNUToolchain/release1882) However, I can tell that c6x's kernel_stat.h only defines two structs: kernel_stat and kernel_stat64: https://elixir.bootlin.com/uclibc-ng/latest/source/libc/sysdeps/linux/c6x/b… And I can also tell that those structs are only used when using xstat conversion functions (__xstat32_conv / xstat_conv) which are only used and present in the __ARCH_HAS_DEPRECATED_SYSCALLS__ == y case. However, c6x does not define __ARCH_HAS_DEPRECATED_SYSCALLS__ So I think I can say that this change does not affect c6x nor other archs. --- Makefile.in | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/Makefile.in b/Makefile.in index 1754040..16ee9ee 100644 --- a/Makefile.in +++ b/Makefile.in @@ -144,14 +144,14 @@ $(top_builddir)include/dl-osinfo.h $(top_builddir)include/not-cancel.h: $(ALL_HEADERS_BITS_COMMON): $(do_ln) $(call rel_srcdir)libc/sysdeps/linux/common/bits/$(@F) $@ -$(ALL_HEADERS_BITS_ARCH): - $(do_ln) $(call rel_srcdir)libc/sysdeps/linux/$(TARGET_ARCH)/bits/$(@F) $@ - ifneq ($(ARCH_HAS_DEPRECATED_SYSCALLS),y) $(ALL_HEADERS_BITS_COMMON_NO_LEGACY): $(do_ln) $(call rel_srcdir)libc/sysdeps/linux/common-generic/bits/$(@F) $@ endif +$(ALL_HEADERS_BITS_ARCH): + $(do_ln) $(call rel_srcdir)libc/sysdeps/linux/$(TARGET_ARCH)/bits/$(@F) $@ + ifneq ($(TARGET_SUBARCH),) $(ALL_HEADERS_BITS_SUBARCH): $(do_ln) $(call rel_srcdir)libc/sysdeps/linux/$(TARGET_ARCH)/bits/$(TARGET_SUBARCH)/$(@F) $@ -- 1.8.3.1

5 years, 5 months

riscv: add the MAP_UNINITIALIZED definition

by Christoph Hellwig

From: Christoph Hellwig <hch(a)lst.de> This avoids a nommu build failure. Signed-off-by: Christoph Hellwig <hch(a)lst.de> --- libc/sysdeps/linux/riscv64/bits/mman.h | 1 + 1 file changed, 1 insertion(+) diff --git a/libc/sysdeps/linux/riscv64/bits/mman.h b/libc/sysdeps/linux/riscv64/bits/mman.h index 316f87d99..fa6f8e6a0 100644 --- a/libc/sysdeps/linux/riscv64/bits/mman.h +++ b/libc/sysdeps/linux/riscv64/bits/mman.h @@ -31,6 +31,7 @@ # define MAP_HUGETLB 0x40000 /* Create huge page mapping. */ # define MAP_SYNC 0x80000 /* Perform synchronous page faults for the mapping. */ +# define MAP_UNINITIALIZED 0x4000000 /* For anonymous mmap, memory could - be uninitialized. */ #endif /* Include generic Linux declarations. */ -- 2.20.1

5 years, 5 months

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devel July 2019