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ARM: VDSO: fix regression with toolchains lacking ld.bfd executable

PATCH New Nathan Lynch 2 participants 4 messages Jul 15, 2015 – Jul 17, 2015 Arm (32-bit)

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Nathan Lynch

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PATCH 1/1 ARM: VDSO: fix regression with toolchains lacking ld.bfd executable

The Sourcery CodeBench Lite 2014.05 toolchain (gcc 4.8.3, binutils 2.24.51) has a GCC which implements -fuse-ld, and it doesn't include the gold linker, but it lacks an ld.bfd executable in its installation. This means that passing -fuse-ld=bfd fails with:

VDSO arch/arm/vdso/vdso.so.raw
collect2: fatal error: cannot find 'ld'

Arguably this is a deficiency in the toolchain, but I suspect it's commonly used enough that it's worth accommodating: just use cc-ldoption (to cause a link attempt) instead of cc-option to test whether we can use -fuse-ld. So -fuse-ld=bfd won't be used with this toolchain, but the build will rightly succeed, just as it does for toolchains which don't implement -fuse-ld (and don't use gold as the default linker).

Note: this will change the failure mode for a corner case I was trying to handle in d2b30cd4b722, where the toolchain defaults to the gold linker and the BFD linker is not found in PATH, from:

VDSO arch/arm/vdso/vdso.so.raw
collect2: fatal error: cannot find 'ld'

i.e. the BFD linker is not found, to:

OBJCOPY arch/arm/vdso/vdso.so
BFD: arch/arm/vdso/vdso.so: Not enough room for program headers, try linking with -N

that is, we fail to prevent gold from being used as the linker, and it produces an object that objcopy can't digest.

Reported-by Baruch Siach <[email protected]>
Tested-by Baruch Siach <[email protected]>
Fixes d2b30cd4b722 ("ARM: 8384/1: VDSO: force use of BFD linker")
Cc stable at vger.kernel.org
Signed-off-by Nathan Lynch <[email protected]>
---
 arch/arm/vdso/Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
arch/arm/vdso/Makefile +1 -1
index 9d259d94e429..1160434eece0 100644
@@ -14,7 +14,7 @@ VDSO_LDFLAGS += -Wl,-z,max-page-size=4096 -Wl,-z,common-page-size=4096
 VDSO_LDFLAGS += -nostdlib -shared
 VDSO_LDFLAGS += $(call cc-ldoption, -Wl$(comma)--hash-style=sysv)
 VDSO_LDFLAGS += $(call cc-ldoption, -Wl$(comma)--build-id)
-VDSO_LDFLAGS += $(call cc-option, -fuse-ld=bfd)
+VDSO_LDFLAGS += $(call cc-ldoption, -fuse-ld=bfd)
 
 obj-$(CONFIG_VDSO) += vdso.o
 extra-$(CONFIG_VDSO) += vdso.lds
Signature · 1 line
2.1.0
#1 lore raw

PATCH 1/1 ARM: VDSO: fix regression with toolchains lacking ld.bfd executable

Hi Nathan,

I just tested it right now and it works, you can add my:

Tested-by Rapha?l Poggi <[email protected]>

2015-07-15 6:34 GMT+02:00 Nathan Lynch <[email protected]>:

Quoted 62 lines

The Sourcery CodeBench Lite 2014.05 toolchain (gcc 4.8.3, binutils 2.24.51) has a GCC which implements -fuse-ld, and it doesn't include the gold linker, but it lacks an ld.bfd executable in its installation. This means that passing -fuse-ld=bfd fails with:

VDSO arch/arm/vdso/vdso.so.raw
collect2: fatal error: cannot find 'ld'

Arguably this is a deficiency in the toolchain, but I suspect it's commonly used enough that it's worth accommodating: just use cc-ldoption (to cause a link attempt) instead of cc-option to test whether we can use -fuse-ld. So -fuse-ld=bfd won't be used with this toolchain, but the build will rightly succeed, just as it does for toolchains which don't implement -fuse-ld (and don't use gold as the default linker).

Note: this will change the failure mode for a corner case I was trying to handle in d2b30cd4b722, where the toolchain defaults to the gold linker and the BFD linker is not found in PATH, from:

VDSO arch/arm/vdso/vdso.so.raw
collect2: fatal error: cannot find 'ld'

i.e. the BFD linker is not found, to:

OBJCOPY arch/arm/vdso/vdso.so
BFD: arch/arm/vdso/vdso.so: Not enough room for program headers, try linking with -N

that is, we fail to prevent gold from being used as the linker, and it produces an object that objcopy can't digest.

Reported-by Baruch Siach <[email protected]>
Tested-by Baruch Siach <[email protected]>
Fixes d2b30cd4b722 ("ARM: 8384/1: VDSO: force use of BFD linker")
Cc stable at vger.kernel.org
Signed-off-by Nathan Lynch <[email protected]>
---
 arch/arm/vdso/Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
arch/arm/vdso/Makefile +1 -2
index 9d259d94e429..1160434eece0 100644
@@ -14,7 +14,7 @@ VDSO_LDFLAGS += -Wl,-z,max-page-size=4096 -Wl,-z,common-page-size=4096
 VDSO_LDFLAGS += -nostdlib -shared
 VDSO_LDFLAGS += $(call cc-ldoption, -Wl$(comma)--hash-style=sysv)
 VDSO_LDFLAGS += $(call cc-ldoption, -Wl$(comma)--build-id)
-VDSO_LDFLAGS += $(call cc-option, -fuse-ld=bfd)
+VDSO_LDFLAGS += $(call cc-ldoption, -fuse-ld=bfd)
 
 obj-$(CONFIG_VDSO) += vdso.o
 extra-$(CONFIG_VDSO) += vdso.lds
--

2.1.0

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#2 lore raw

PATCH 1/1 ARM: VDSO: fix regression with toolchains lacking ld.bfd executable

Quoted 5 lines · Rapha?l Poggi

Hi Nathan,

I just tested it right now and it works, you can add my:

Tested-by Rapha?l Poggi <[email protected]>

Thanks. Are you also using a CodeBench toolchain, or something else?

#3 lore raw

PATCH 1/1 ARM: VDSO: fix regression with toolchains lacking ld.bfd executable

Yes, I use the CodeBench Lite 2014.05 with gcc 4.8.3

2015-07-17 0:17 GMT+02:00 Nathan Lynch <[email protected]>:

Quoted 14 lines · Rapha?l Poggi
Quoted 5 lines

Hi Nathan,

I just tested it right now and it works, you can add my:

Tested-by Rapha?l Poggi <[email protected]>

Thanks. Are you also using a CodeBench toolchain, or something else?

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linux-arm-kernel mailing list
linux-arm-kernel at lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel