April 2017 - devel - example.com

[PATCH] pthread_getcpuclockid.c: fix clockid calculation
by Sergey Korolev 12 May '17

12 May '17

Current uClibc-ng version incorrectly calculates clockid in pthread_getcpuclockid (at least for modern kernels). The simplest test program #include <time.h> #include <errno.h> #include <stdio.h> #include <stdlib.h> #include <pthread.h> int main() { clockid_t clk; struct timespec ts; const int err = pthread_getcpuclockid(pthread_self(), &clk); if (err != 0) { errno = err; perror("pthread_getcpuclockid"); return EXIT_FAILURE; } if (clock_gettime(clk, &ts) == -1) { perror("clock_gettime"); return EXIT_FAILURE; } printf("Thread time is %lu.%06lu.\n", ts.tv_sec, ts.tv_nsec / 1000); return EXIT_SUCCESS; } fails with clock_gettime: Invalid argument Tested on Linux 3.4 / MIPS built with GCC 5.4.0. Other implementations, for example musl, use a simple calculation https://git.musl-libc.org/cgit/musl/tree/src/thread/pthread_getcpuclockid.c Looks strange, but the official glibc repository https://sourceware.org/git/?p=glibc.git;a=blob_plain;f=nptl/pthread_getcpuc… has the same implementation as in uClibc-ng. This fork https://github.com/lattera/glibc/blob/master/nptl/sysdeps/unix/sysv/linux/p… use more accurate approach relying on __NR_clock_getres (defined in the kernel since 2.6.24) with MAKE_THREAD_CPUCLOCK macro copied from the kernel ( http://lxr.free-electrons.com/source/include/linux/posix-timers.h?v=2.6.24#…, Linux 4.10 has the same one). I propose an intermediate solution: use MAKE_THREAD_CPUCLOCK like computation of clockid when __NR_clock_getres defined and do a fallback to an older implementation when not.

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new release 1.0.24
by Waldemar Brodkorb 22 Apr '17

22 Apr '17

Hi embedded hackers, I released 1.0.24 today. Mostly bugfixes and cleanups. The aarch64 c++ issue is fixed and the long double wrappers are available for all architectures now. (lvm2 build issues) I removed old fnmatch/regex implementations to simplify the code base. have fun, Waldemar

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[PATCH] Same iteration variable used for inner and outer loop
by Cupertino Miranda 11 Apr '17

11 Apr '17

Inner loop was using same counter variable (i) as the outer loop, therefore making outer loop terminate before it visited all of the ELF program segments. Surrounding code in this inner loop clearly shows the intention that this loop should not affect the outer one, therefore leading me to the conclusion that this should be a bug an not expected code. This bug was detected due to some other bug in ARC binutils that kept setting TEXTREL for any PIE application. Apart from the but, I have also moved the debug message inside of the TEXTREL condition as mprotect is only really called if TELTREL is set. --- ldso/ldso/ldso.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/ldso/ldso/ldso.c b/ldso/ldso/ldso.c index 4e8a49e..a077f20 100644 --- a/ldso/ldso/ldso.c +++ b/ldso/ldso/ldso.c @@ -668,12 +668,13 @@ of this helper program; chances are you did not intend to run this program.\n\ * dynamic linking. We can set the protection back * again once we are done. */ - _dl_debug_early("calling mprotect on the application program\n"); /* Now cover the application program. */ if (app_tpnt->dynamic_info[DT_TEXTREL]) { + int j; ElfW(Phdr) *ppnt_outer = ppnt; + _dl_debug_early("calling mprotect on the application program\n"); ppnt = (ElfW(Phdr) *) auxvt[AT_PHDR].a_un.a_val; - for (i = 0; i < auxvt[AT_PHNUM].a_un.a_val; i++, ppnt++) { + for (j = 0; j < auxvt[AT_PHNUM].a_un.a_val; j++, ppnt++) { if (ppnt->p_type == PT_LOAD && !(ppnt->p_flags & PF_W)) _dl_mprotect((void *) (DL_RELOC_ADDR(app_tpnt->loadaddr, ppnt->p_vaddr) & PAGE_ALIGN), (DL_RELOC_ADDR(app_tpnt->loadaddr, ppnt->p_vaddr) & ADDR_ALIGN) + -- 2.9.0

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[PATCH] ldso: exit if zalloc can't alloc memory
by Vineet Gupta 11 Apr '17

11 Apr '17

_dl_zalloc callers don't check for allocaton failure. It kind of makes sense since such early allocations are unlikely to fail, and even if they do, ldso would segv anyways thus bringing the issue to attention. However there's a gcc nuance which led to this patch. It seems gcc at -O2 (for DODEBUG build), does additional coge gen analysis for pointer dereference from erroneous paths and it "isolates" such code paths with a intrinsic abort/trap etc. The ldso code fragment which was triggering this: | add_ldso(struct dyn_elf *rpnt) | if (rpnt) | ... | else | rpnt = _dl_zalloc() | | rpnt->dyn = tpnt <---- potential NULL pointer deref ARC gcc currently generates an abort() call which doesn't exist in ldso, causing link errors (with a newer vrsion of binutils). ARM gcc 6.2.1 behaves similarly, altough instead of abort, it generates a trap inducing UDF instruction | 367c: ebfffb79 bl 2468 <_dl_malloc> | 3680: e51b2068 ldr r2, [fp, #-104] ; 0xffffff98 | 3684: e3500000 cmp r0, #0 | 3688: 0a000006 beq 36a8 <_dl_add_elf_hash_table+0x280> | ... | 36a8: e5862000 str r2, [r6] | 36ac: e7f000f0 udf # So add an explict dl_exit() in dl_zalloc error case to beat the compiler. Note that this error propagagtion analysis stops if the function in consideration (_dl_zalloc) is NOT inlined. Hence the reason it only shows up for DODEBUG builds which builds ldso at -O2 which is more aggressive about inlining. If this patch is not considered worth applying then the workaround suggested by Claudiu is to to build ldso with -fno-isolate-erroneous-paths-dereference Signed-off-by: Vineet Gupta <vgupta(a)synopsys.com> --- ldso/ldso/ldso.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/ldso/ldso/ldso.c b/ldso/ldso/ldso.c index 4e8a49ef5f91..539975bcfb0c 100644 --- a/ldso/ldso/ldso.c +++ b/ldso/ldso/ldso.c @@ -259,6 +259,8 @@ static void *_dl_zalloc(size_t size) void *p = _dl_malloc(size); if (p) _dl_memset(p, 0, size); + else + _dl_exit(1); return p; } -- 2.7.4

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[PATCH] ldso/arc: fix debug prints
by Vineet Gupta 11 Apr '17

11 Apr '17

Signed-off-by: Vineet Gupta <vgupta(a)synopsys.com> --- ldso/ldso/arc/elfinterp.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/ldso/ldso/arc/elfinterp.c b/ldso/ldso/arc/elfinterp.c index 2f0cf7f6635b..c164d5dae6bf 100644 --- a/ldso/ldso/arc/elfinterp.c +++ b/ldso/ldso/arc/elfinterp.c @@ -179,8 +179,8 @@ _dl_do_reloc(struct elf_resolve *tpnt, struct r_scope_elem *scope, log_entry: #if defined __SUPPORT_LD_DEBUG__ if (_dl_debug_detail) - _dl_dprintf(_dl_debug_file,"\tpatched: %lx ==> %lx @ %pl: addend %x ", - old_val, *reloc_addr, reloc_addr, rpnt->r_addend); + _dl_dprintf(_dl_debug_file,"\tpatched: %x ==> %x @ %x", + old_val, *reloc_addr, reloc_addr); #endif return 0; @@ -215,7 +215,7 @@ _dl_do_lazy_reloc(struct elf_resolve *tpnt, struct r_scope_elem *scope, #if defined __SUPPORT_LD_DEBUG__ if (_dl_debug_reloc && _dl_debug_detail) - _dl_dprintf(_dl_debug_file, "\tpatched: %lx ==> %lx @ %pl\n", + _dl_dprintf(_dl_debug_file, "\tpatched: %x ==> %x @ %x\n", old_val, *reloc_addr, reloc_addr); #endif -- 2.7.4

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RPC removal suggestion
by Waldemar Brodkorb 04 Apr '17

04 Apr '17

Hi, What do you think about following patch? We had some discussion about this recently on the buildroot mailinglist. Any other use cases other than rpcbind/nfs-utils you can think of? best regards Waldemar

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uClibc-ng 1.0.23 released
by Waldemar Brodkorb 04 Apr '17

04 Apr '17

Hi, I released uClibc-ng 1.0.23 yesterday. Mostly bugfixes. I have removed the internal RPC implementation, which is mostly unusable nowadays as most applications force libtirpc usage (like rpcbind). For nios2 I added some ld.so code with the help of Thorsten, but it is still unusable. best regards Waldemar

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[PATCH] ldso: don't discard sysmbols for DODEBUG builds
by Vineet Gupta 03 Apr '17

03 Apr '17

the --discard-* toggles take away the symbols which comes in the way when staring at objdumps for debugging low level issues So don't discard symbols for DODEBUG builds before ----- 3388: j_s.d [blink] 338a: add_s sp,sp,0x18 338c: b.d 332c <_dl_add_elf_hash_table+0x50> 3390: mov_s r2,0 3392: nop_s 3394: push_s blink <--- function not called out 3396: st.aw r13,[sp,-20] 339a: std r14r15,[sp,4] 339e: std r16r17,[sp,12] after ----- 3388: j_s.d [blink] 338a: add_s sp,sp,0x18 338c: b.d 332c <_dl_add_elf_hash_table+0x50> 3390: mov_s r2,0 3392: nop_s 00003394 <add_ldso.isra.9>: 3394: push_s blink 3396: st.aw r13,[sp,-20] 339a: std r14r15,[sp,4] 339e: std r16r17,[sp,12] Signed-off-by: Vineet Gupta <vgupta(a)synopsys.com> --- ldso/ldso/Makefile.in | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/ldso/ldso/Makefile.in b/ldso/ldso/Makefile.in index 320e4488ba22..acb1a5b2ac15 100644 --- a/ldso/ldso/Makefile.in +++ b/ldso/ldso/Makefile.in @@ -51,8 +51,11 @@ LDFLAGS-$(UCLIBC_LDSO_NAME).so := $(LDFLAGS_NOSTRIP) -Wl,-z,defs endif LDFLAGS-$(UCLIBC_LDSO_NAME).so += -Wl,-e,$(SYMBOL_PREFIX)_start \ -Wl,-z,now -Wl,-Bsymbolic \ - -Wl,--export-dynamic $(CFLAG_-Wl--sort-common) -Wl,--discard-locals \ - $(CFLAG_-Wl--discard-all) -Wl,--no-undefined + -Wl,--export-dynamic $(CFLAG_-Wl--sort-common) -Wl,--no-undefined + +ifneq ($(DODEBUG),y) + LDFLAGS-$(UCLIBC_LDSO_NAME).so += -Wl,--discard-locals $(CFLAG_-Wl--discard-all) +endif LDFLAGS-$(LDSO_PRELINK_SUPPORT)-$(UCLIBC_LDSO_NAME).so += -Wl,-defsym=$(SYMBOL_PREFIX)_begin=0 -- 2.7.4

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