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[PATCH v2] um: Avoid longjmp/setjmp symbol clashes with libpthread.a

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  [PATCH v2] um: Avoid longjmp/setjmp symbol clashes with libpthread.a Florian Fainelli <f.fainelli@gmail.com> - 2017-05-24 02:40 +0200
    Re: [PATCH v2] um: Avoid longjmp/setjmp symbol clashes with  libpthread.a Richard Weinberger <richard@nod.at> - 2017-05-24 09:10 +0200
      Re: [PATCH v2] um: Avoid longjmp/setjmp symbol clashes with  libpthread.a Florian Fainelli <f.fainelli@gmail.com> - 2017-05-24 18:20 +0200

#1649040 — [PATCH v2] um: Avoid longjmp/setjmp symbol clashes with libpthread.a

Building a statically linked UML kernel on a Centos 6.9 host resulted in
the following linking failure (GCC 4.4, glibc-2.12):

/usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../lib64/libpthread.a(libpthread.o):
In function `siglongjmp':
(.text+0x8490): multiple definition of `longjmp'
arch/x86/um/built-in.o:/local/users/fainelli/openwrt/trunk/build_dir/target-x86_64_musl/linux-uml/linux-4.4.69/arch/x86/um/setjmp_64.S:44:
first defined here
/usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../lib64/libpthread.a(libpthread.o):
In function `sem_open':
(.text+0x77cd): warning: the use of `mktemp' is dangerous, better use
`mkstemp'
collect2: ld returned 1 exit status
make[4]: *** [vmlinux] Error 1

Adopt a solution similar to the one done for vmap where we define
longjmp/setjmp to be kernel_longjmp/setjmp. In the process, make sure we
do rename the functions in arch/x86/um/setjmp_*.S accordingly.

Fixes: a7df4716d195 ("um: link with -lpthread")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
---
Changes in v2:
- fix typo introduced on longjmp

 arch/um/Makefile        |  4 ++++
 arch/x86/um/setjmp_32.S | 16 ++++++++--------
 arch/x86/um/setjmp_64.S | 16 ++++++++--------
 3 files changed, 20 insertions(+), 16 deletions(-)

diff --git a/arch/um/Makefile b/arch/um/Makefile
index 0ca46ededfc7..6ca4f66085c1 100644
--- a/arch/um/Makefile
+++ b/arch/um/Makefile
@@ -59,10 +59,14 @@ KBUILD_CPPFLAGS += -I$(srctree)/$(HOST_DIR)/um
 # Same things for in6addr_loopback and mktime - found in libc. For these two we
 # only get link-time error, luckily.
 #
+# -Dlongjmp=kernel_longjmp prevents anything from referencing the libpthread.a
+# embedded copy of longjmp, same thing for setjmp.
+#
 # These apply to USER_CFLAGS to.
 
 KBUILD_CFLAGS += $(CFLAGS) $(CFLAGS-y) -D__arch_um__ \
 	$(ARCH_INCLUDE) $(MODE_INCLUDE) -Dvmap=kernel_vmap	\
+	-Dlongjmp=kernel_longjmp -Dsetjmp=kernel_setjmp \
 	-Din6addr_loopback=kernel_in6addr_loopback \
 	-Din6addr_any=kernel_in6addr_any -Dstrrchr=kernel_strrchr
 
diff --git a/arch/x86/um/setjmp_32.S b/arch/x86/um/setjmp_32.S
index b766792c9933..39053192918d 100644
--- a/arch/x86/um/setjmp_32.S
+++ b/arch/x86/um/setjmp_32.S
@@ -16,9 +16,9 @@
 
 	.text
 	.align 4
-	.globl setjmp
-	.type setjmp, @function
-setjmp:
+	.globl kernel_setjmp
+	.type kernel_setjmp, @function
+kernel_setjmp:
 #ifdef _REGPARM
 	movl %eax,%edx
 #else
@@ -35,13 +35,13 @@ setjmp:
 	movl %ecx,20(%edx)		# Return address
 	ret
 
-	.size setjmp,.-setjmp
+	.size kernel_setjmp,.-kernel_setjmp
 
 	.text
 	.align 4
-	.globl longjmp
-	.type longjmp, @function
-longjmp:
+	.globl kernel_longjmp
+	.type kernel_longjmp, @function
+kernel_longjmp:
 #ifdef _REGPARM
 	xchgl %eax,%edx
 #else
@@ -55,4 +55,4 @@ longjmp:
 	movl 16(%edx),%edi
 	jmp *20(%edx)
 
-	.size longjmp,.-longjmp
+	.size kernel_longjmp,.-kernel_longjmp
diff --git a/arch/x86/um/setjmp_64.S b/arch/x86/um/setjmp_64.S
index 45f547b4043e..c56942e1a38c 100644
--- a/arch/x86/um/setjmp_64.S
+++ b/arch/x86/um/setjmp_64.S
@@ -18,9 +18,9 @@
 
 	.text
 	.align 4
-	.globl setjmp
-	.type setjmp, @function
-setjmp:
+	.globl kernel_setjmp
+	.type kernel_setjmp, @function
+kernel_setjmp:
 	pop  %rsi			# Return address, and adjust the stack
 	xorl %eax,%eax			# Return value
 	movq %rbx,(%rdi)
@@ -34,13 +34,13 @@ setjmp:
 	movq %rsi,56(%rdi)		# Return address
 	ret
 
-	.size setjmp,.-setjmp
+	.size kernel_setjmp,.-kernel_setjmp
 
 	.text
 	.align 4
-	.globl longjmp
-	.type longjmp, @function
-longjmp:
+	.globl kernel_longjmp
+	.type kernel_longjmp, @function
+kernel_longjmp:
 	movl %esi,%eax			# Return value (int)
 	movq (%rdi),%rbx
 	movq 8(%rdi),%rsp
@@ -51,4 +51,4 @@ longjmp:
 	movq 48(%rdi),%r15
 	jmp *56(%rdi)
 
-	.size longjmp,.-longjmp
+	.size kernel_longjmp,.-kernel_longjmp
-- 
2.12.2

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#1649167 — Re: [PATCH v2] um: Avoid longjmp/setjmp symbol clashes with libpthread.a

Florian,

Am 24.05.2017 um 02:32 schrieb Florian Fainelli:
> Building a statically linked UML kernel on a Centos 6.9 host resulted in
> the following linking failure (GCC 4.4, glibc-2.12):
> 
> /usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../lib64/libpthread.a(libpthread.o):
> In function `siglongjmp':
> (.text+0x8490): multiple definition of `longjmp'
> arch/x86/um/built-in.o:/local/users/fainelli/openwrt/trunk/build_dir/target-x86_64_musl/linux-uml/linux-4.4.69/arch/x86/um/setjmp_64.S:44:
> first defined here
> /usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../lib64/libpthread.a(libpthread.o):
> In function `sem_open':
> (.text+0x77cd): warning: the use of `mktemp' is dangerous, better use
> `mkstemp'
> collect2: ld returned 1 exit status
> make[4]: *** [vmlinux] Error 1
> 
> Adopt a solution similar to the one done for vmap where we define
> longjmp/setjmp to be kernel_longjmp/setjmp. In the process, make sure we
> do rename the functions in arch/x86/um/setjmp_*.S accordingly.

What is not so clear to me, why are you facing this build issue and other users, including me,
not?

Thanks,
//richard

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#1649743 — Re: [PATCH v2] um: Avoid longjmp/setjmp symbol clashes with libpthread.a

On 05/24/2017 12:02 AM, Richard Weinberger wrote:
> Florian,
> 
> Am 24.05.2017 um 02:32 schrieb Florian Fainelli:
>> Building a statically linked UML kernel on a Centos 6.9 host resulted in
>> the following linking failure (GCC 4.4, glibc-2.12):
>>
>> /usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../lib64/libpthread.a(libpthread.o):
>> In function `siglongjmp':
>> (.text+0x8490): multiple definition of `longjmp'
>> arch/x86/um/built-in.o:/local/users/fainelli/openwrt/trunk/build_dir/target-x86_64_musl/linux-uml/linux-4.4.69/arch/x86/um/setjmp_64.S:44:
>> first defined here
>> /usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../lib64/libpthread.a(libpthread.o):
>> In function `sem_open':
>> (.text+0x77cd): warning: the use of `mktemp' is dangerous, better use
>> `mkstemp'
>> collect2: ld returned 1 exit status
>> make[4]: *** [vmlinux] Error 1
>>
>> Adopt a solution similar to the one done for vmap where we define
>> longjmp/setjmp to be kernel_longjmp/setjmp. In the process, make sure we
>> do rename the functions in arch/x86/um/setjmp_*.S accordingly.
> 
> What is not so clear to me, why are you facing this build issue and other users, including me,
> not?

Presumably because we are not using the same glibc version? The one I
have installed on this machine is glibc-2.12, do you want me to attach a
copy of it?
-- 
Florian

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