| Message ID | 1458335299-27409-8-git-send-email-thomas.petazzoni@free-electrons.com |
|---|---|
| State | Accepted |
| Headers | show |
On 03/18/16 22:08, Thomas Petazzoni wrote: > As explained by Waldemar, enabling DOPIC in uClibc will lead to the > creation of a Position Independent library. In turn, this will cause > elf2flt to generate a "Has-PIC-GOT" flat binary, which doesn't work on > ARM. In fact, elf2flt on ARM really expect to have non-PIC code as ^^^^^^expects > input, so we must disable DOPIC in the uClibc configuration. > > Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com> Otherwise: Reviewed-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be> Though I wonder: shouldn't uClibc detect this by itself? Similar to the BX handling that you removed. Adding Waldemar in Cc to think about this. Regards, Arnout > --- > package/uclibc/uclibc.mk | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/package/uclibc/uclibc.mk b/package/uclibc/uclibc.mk > index ad94494..e3e45f7 100644 > --- a/package/uclibc/uclibc.mk > +++ b/package/uclibc/uclibc.mk > @@ -82,6 +82,12 @@ ifeq ($(BR2_GCC_VERSION_4_7_X)$(BR2_GCC_VERSION_4_8_X):$(BR2_ARM_INSTRUCTIONS_TH > UCLIBC_EXTRA_CFLAGS += -marm > endif > > +ifeq ($(BR2_BINFMT_FLAT),y) > +define UCLIBC_ARM_BINFMT_FLAT > + $(call KCONFIG_DISABLE_OPT,DOPIC,$(@D)/.config) > +endef > +endif > + > endif # arm > > # > @@ -354,6 +360,7 @@ define UCLIBC_KCONFIG_FIXUP_CMDS > $(UCLIBC_ARC_TYPE_CONFIG) > $(UCLIBC_ARC_PAGE_SIZE_CONFIG) > $(UCLIBC_ARM_ABI_CONFIG) > + $(UCLIBC_ARM_BINFMT_FLAT) > $(UCLIBC_MIPS_ABI_CONFIG) > $(UCLIBC_MIPS_ISA_CONFIG) > $(UCLIBC_SH_TYPE_CONFIG) >
+Waldemar On 18 March 2016 at 18:08, Thomas Petazzoni <thomas.petazzoni@free-electrons.com> wrote: > As explained by Waldemar, enabling DOPIC in uClibc will lead to the > creation of a Position Independent library. In turn, this will cause > elf2flt to generate a "Has-PIC-GOT" flat binary, which doesn't work on > ARM. In fact, elf2flt on ARM really expect to have non-PIC code as > input, so we must disable DOPIC in the uClibc configuration. > While testing on LPC4350, I found that Lua is built with the Has-PIC-GOT flag: $ output/host/usr/bin/arm-buildroot-uclinux-uclibcgnueabi-flthdr output/target/usr/bin/lua output/target/usr/bin/lua Magic: bFLT Rev: 4 Build Date: Sat Mar 19 16:14:03 2016 Entry: 0x45 Data Start: 0x1f08c Data End: 0x23ed8 BSS End: 0x260c0 Stack Size: 0x1000 Reloc Start: 0x23ed8 Reloc Count: 0x214 Flags: 0x2 ( Has-PIC-GOT ) The Lua interpreter is not loaded by the binfmt_flat loader, and the kernel says: BINFMT_FLAT: reloc outside program 0x7fffd3e4 (0 - 0x26080/0x1f04c), killing lua! When DEBUG is defined in fs/binfmt_flat.c, the kernel says: BINFMT_FLAT: reference 0xffd3e4 to shared library 127, killing lua! On the other side, atftp throws the same error: BINFMT_FLAT: reference 0xa0100 to shared library 161, killing atftp! Any ideas?
Hello, On Sat, 19 Mar 2016 16:27:19 -0300, Ezequiel Garcia wrote: > On 18 March 2016 at 18:08, Thomas Petazzoni > <thomas.petazzoni@free-electrons.com> wrote: > > As explained by Waldemar, enabling DOPIC in uClibc will lead to the > > creation of a Position Independent library. In turn, this will cause > > elf2flt to generate a "Has-PIC-GOT" flat binary, which doesn't work on > > ARM. In fact, elf2flt on ARM really expect to have non-PIC code as > > input, so we must disable DOPIC in the uClibc configuration. > > > > While testing on LPC4350, I found that Lua is built with the Has-PIC-GOT flag: > > $ output/host/usr/bin/arm-buildroot-uclinux-uclibcgnueabi-flthdr > output/target/usr/bin/lua > output/target/usr/bin/lua > Magic: bFLT > Rev: 4 > Build Date: Sat Mar 19 16:14:03 2016 > Entry: 0x45 > Data Start: 0x1f08c > Data End: 0x23ed8 > BSS End: 0x260c0 > Stack Size: 0x1000 > Reloc Start: 0x23ed8 > Reloc Count: 0x214 > Flags: 0x2 ( Has-PIC-GOT ) > > The Lua interpreter is not loaded by the binfmt_flat loader, and the > kernel says: > > BINFMT_FLAT: reloc outside program 0x7fffd3e4 (0 - 0x26080/0x1f04c), > killing lua! > > When DEBUG is defined in fs/binfmt_flat.c, the kernel says: > > BINFMT_FLAT: reference 0xffd3e4 to shared library 127, killing lua! > > On the other side, atftp throws the same error: > > BINFMT_FLAT: reference 0xa0100 to shared library 161, killing atftp! > > Any ideas? Thanks for this testing. Is lua using threads by any chance? I for sure know that the thread support is causing errors similar to the one that you are reporting. The ARM noMMU support is preliminary, for now I've only tested Busybox and a few other small programs. Once this preliminary support is merged, we can start looking at additional problems. For example, adding a check at the end of the build that all binaries have the appropriate BFLT flags. Waldemar: in fact maybe the issue I had with threads is that as soon as you link with -lpthread, you have a Has-PIC-GOT flagged BFLT. I'll check that when I find some time. Best regards, Thomas
On 19 March 2016 at 17:50, Thomas Petazzoni <thomas.petazzoni@free-electrons.com> wrote: > Hello, > > On Sat, 19 Mar 2016 16:27:19 -0300, Ezequiel Garcia wrote: > >> On 18 March 2016 at 18:08, Thomas Petazzoni >> <thomas.petazzoni@free-electrons.com> wrote: >> > As explained by Waldemar, enabling DOPIC in uClibc will lead to the >> > creation of a Position Independent library. In turn, this will cause >> > elf2flt to generate a "Has-PIC-GOT" flat binary, which doesn't work on >> > ARM. In fact, elf2flt on ARM really expect to have non-PIC code as >> > input, so we must disable DOPIC in the uClibc configuration. >> > >> >> While testing on LPC4350, I found that Lua is built with the Has-PIC-GOT flag: >> >> $ output/host/usr/bin/arm-buildroot-uclinux-uclibcgnueabi-flthdr >> output/target/usr/bin/lua >> output/target/usr/bin/lua >> Magic: bFLT >> Rev: 4 >> Build Date: Sat Mar 19 16:14:03 2016 >> Entry: 0x45 >> Data Start: 0x1f08c >> Data End: 0x23ed8 >> BSS End: 0x260c0 >> Stack Size: 0x1000 >> Reloc Start: 0x23ed8 >> Reloc Count: 0x214 >> Flags: 0x2 ( Has-PIC-GOT ) >> >> The Lua interpreter is not loaded by the binfmt_flat loader, and the >> kernel says: >> >> BINFMT_FLAT: reloc outside program 0x7fffd3e4 (0 - 0x26080/0x1f04c), >> killing lua! >> >> When DEBUG is defined in fs/binfmt_flat.c, the kernel says: >> >> BINFMT_FLAT: reference 0xffd3e4 to shared library 127, killing lua! >> >> On the other side, atftp throws the same error: >> >> BINFMT_FLAT: reference 0xa0100 to shared library 161, killing atftp! >> >> Any ideas? > > Thanks for this testing. Is lua using threads by any chance? I for sure > know that the thread support is causing errors similar to the one that > you are reporting. > No, Lua doesn't uses threads. > The ARM noMMU support is preliminary, for now I've only tested Busybox > and a few other small programs. Once this preliminary support is > merged, we can start looking at additional problems. Sure, I'm not at all objecting this patchset. I've tested some programs and all of them seem to work fine, with the sole exception of lua and atftp. Interestingly, the atftp binary does not have the Has-PIC-GOT flag set... so I don't know if it's the real reason for the issue.
Hello, On Sat, 19 Mar 2016 17:11:58 +0100, Arnout Vandecappelle wrote: > Though I wonder: shouldn't uClibc detect this by itself? Similar to the BX > handling that you removed. Adding Waldemar in Cc to think about this. I don't yet fully understand the different modes of elf2flt, and why DOPIC affects what elf2flt is capable of doing/not doing. However, if as Waldemar told me, a uClibc built with DOPIC=y will not work with elf2flt on ARM, then I could indeed send a patch to uClibc to disable DOPIC on ARM/noMMU. Thanks! Thomas
diff --git a/package/uclibc/uclibc.mk b/package/uclibc/uclibc.mk index ad94494..e3e45f7 100644 --- a/package/uclibc/uclibc.mk +++ b/package/uclibc/uclibc.mk @@ -82,6 +82,12 @@ ifeq ($(BR2_GCC_VERSION_4_7_X)$(BR2_GCC_VERSION_4_8_X):$(BR2_ARM_INSTRUCTIONS_TH UCLIBC_EXTRA_CFLAGS += -marm endif +ifeq ($(BR2_BINFMT_FLAT),y) +define UCLIBC_ARM_BINFMT_FLAT + $(call KCONFIG_DISABLE_OPT,DOPIC,$(@D)/.config) +endef +endif + endif # arm # @@ -354,6 +360,7 @@ define UCLIBC_KCONFIG_FIXUP_CMDS $(UCLIBC_ARC_TYPE_CONFIG) $(UCLIBC_ARC_PAGE_SIZE_CONFIG) $(UCLIBC_ARM_ABI_CONFIG) + $(UCLIBC_ARM_BINFMT_FLAT) $(UCLIBC_MIPS_ABI_CONFIG) $(UCLIBC_MIPS_ISA_CONFIG) $(UCLIBC_SH_TYPE_CONFIG)
As explained by Waldemar, enabling DOPIC in uClibc will lead to the creation of a Position Independent library. In turn, this will cause elf2flt to generate a "Has-PIC-GOT" flat binary, which doesn't work on ARM. In fact, elf2flt on ARM really expect to have non-PIC code as input, so we must disable DOPIC in the uClibc configuration. Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com> --- package/uclibc/uclibc.mk | 7 +++++++ 1 file changed, 7 insertions(+)