| Message ID | 20201108203737.94270-1-natechancellor@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | riscv: Explicitly specify the build id style in vDSO Makefile again | expand |
On Sun, Nov 8, 2020 at 12:37 PM Nathan Chancellor <natechancellor@gmail.com> wrote: > > Commit a96843372331 ("kbuild: explicitly specify the build id style") > explicitly set the build ID style to SHA1. Commit c2c81bb2f691 ("RISC-V: > Fix the VDSO symbol generaton for binutils-2.35+") undid this change, > likely unintentionally. > > Restore it so that the build ID style stays consistent across the tree > regardless of linker. > > Fixes: c2c81bb2f691 ("RISC-V: Fix the VDSO symbol generaton for binutils-2.35+") > Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> Thanks for the fixup! Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> (I'm curious what --build-id linker flag does, and what kind of spooky bugs that led to a96843372331?) > --- > arch/riscv/kernel/vdso/Makefile | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/riscv/kernel/vdso/Makefile b/arch/riscv/kernel/vdso/Makefile > index cb8f9e4cfcbf..0cfd6da784f8 100644 > --- a/arch/riscv/kernel/vdso/Makefile > +++ b/arch/riscv/kernel/vdso/Makefile > @@ -44,7 +44,7 @@ SYSCFLAGS_vdso.so.dbg = $(c_flags) > $(obj)/vdso.so.dbg: $(src)/vdso.lds $(obj-vdso) FORCE > $(call if_changed,vdsold) > SYSCFLAGS_vdso.so.dbg = -shared -s -Wl,-soname=linux-vdso.so.1 \ > - -Wl,--build-id -Wl,--hash-style=both > + -Wl,--build-id=sha1 -Wl,--hash-style=both > > # We also create a special relocatable object that should mirror the symbol > # table and layout of the linked DSO. With ld --just-symbols we can then > > base-commit: c2c81bb2f69138f902e1a58d3bef6ad97fb8a92c > -- > 2.29.2 > > -- > You received this message because you are subscribed to the Google Groups "Clang Built Linux" group. > To unsubscribe from this group and stop receiving emails from it, send an email to clang-built-linux+unsubscribe@googlegroups.com. > To view this discussion on the web visit https://groups.google.com/d/msgid/clang-built-linux/20201108203737.94270-1-natechancellor%40gmail.com.
On Thu, Nov 12, 2020 at 4:53 PM Nick Desaulniers <ndesaulniers@google.com> wrote: > > On Sun, Nov 8, 2020 at 12:37 PM Nathan Chancellor > <natechancellor@gmail.com> wrote: > > > > Commit a96843372331 ("kbuild: explicitly specify the build id style") > > explicitly set the build ID style to SHA1. Commit c2c81bb2f691 ("RISC-V: > > Fix the VDSO symbol generaton for binutils-2.35+") undid this change, > > likely unintentionally. > > > > Restore it so that the build ID style stays consistent across the tree > > regardless of linker. > > > > Fixes: c2c81bb2f691 ("RISC-V: Fix the VDSO symbol generaton for binutils-2.35+") > > Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> > > Thanks for the fixup! > > Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> > > (I'm curious what --build-id linker flag does, and what kind of spooky > bugs that led to a96843372331?) > --build-id generates a unique "build id" for the build. It can use several different algorithms to do this. The BFD linker uses sha1 by default while LLD uses a "fast" algorithm. The difference is that the fast algorithm generates a shorter build id. This shouldn't matter in general, but there are some tools out there that expect the build id to be of a certain length, i.e. the BFD style's length, because BFD is more prevalent. The obvious response "well, why don't they just change the expected length?" is difficult in all situations. (Once an assumption is made, it's hard to backtrack.) You can add this if you like: Reviewed-by: Bill Wendling <morbo@google.com> > > --- > > arch/riscv/kernel/vdso/Makefile | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/arch/riscv/kernel/vdso/Makefile b/arch/riscv/kernel/vdso/Makefile > > index cb8f9e4cfcbf..0cfd6da784f8 100644 > > --- a/arch/riscv/kernel/vdso/Makefile > > +++ b/arch/riscv/kernel/vdso/Makefile > > @@ -44,7 +44,7 @@ SYSCFLAGS_vdso.so.dbg = $(c_flags) > > $(obj)/vdso.so.dbg: $(src)/vdso.lds $(obj-vdso) FORCE > > $(call if_changed,vdsold) > > SYSCFLAGS_vdso.so.dbg = -shared -s -Wl,-soname=linux-vdso.so.1 \ > > - -Wl,--build-id -Wl,--hash-style=both > > + -Wl,--build-id=sha1 -Wl,--hash-style=both > > > > # We also create a special relocatable object that should mirror the symbol > > # table and layout of the linked DSO. With ld --just-symbols we can then > > > > base-commit: c2c81bb2f69138f902e1a58d3bef6ad97fb8a92c > > -- > > 2.29.2 > > > > -- > > You received this message because you are subscribed to the Google Groups "Clang Built Linux" group. > > To unsubscribe from this group and stop receiving emails from it, send an email to clang-built-linux+unsubscribe@googlegroups.com. > > To view this discussion on the web visit https://groups.google.com/d/msgid/clang-built-linux/20201108203737.94270-1-natechancellor%40gmail.com. > > > > -- > Thanks, > ~Nick Desaulniers
On Thu, Nov 12, 2020 at 5:03 PM Bill Wendling <morbo@google.com> wrote: > > On Thu, Nov 12, 2020 at 4:53 PM Nick Desaulniers > <ndesaulniers@google.com> wrote: > > > > On Sun, Nov 8, 2020 at 12:37 PM Nathan Chancellor > > <natechancellor@gmail.com> wrote: > > > > > > Commit a96843372331 ("kbuild: explicitly specify the build id style") > > > explicitly set the build ID style to SHA1. Commit c2c81bb2f691 ("RISC-V: > > > Fix the VDSO symbol generaton for binutils-2.35+") undid this change, > > > likely unintentionally. > > > > > > Restore it so that the build ID style stays consistent across the tree > > > regardless of linker. > > > > > > Fixes: c2c81bb2f691 ("RISC-V: Fix the VDSO symbol generaton for binutils-2.35+") > > > Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> > > > > Thanks for the fixup! > > > > Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> > > > > (I'm curious what --build-id linker flag does, and what kind of spooky > > bugs that led to a96843372331?) > > > --build-id generates a unique "build id" for the build. It can use > several different algorithms to do this. The BFD linker uses sha1 by > default while LLD uses a "fast" algorithm. The difference is that the > fast algorithm generates a shorter build id. This shouldn't matter in > general, but there are some tools out there that expect the build id > to be of a certain length, i.e. the BFD style's length, because BFD is > more prevalent. The obvious response "well, why don't they just change > the expected length?" is difficult in all situations. (Once an > assumption is made, it's hard to backtrack.) > > You can add this if you like: > > Reviewed-by: Bill Wendling <morbo@google.com> Cool, thanks for the context, and the review! > > > > --- > > > arch/riscv/kernel/vdso/Makefile | 2 +- > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > diff --git a/arch/riscv/kernel/vdso/Makefile b/arch/riscv/kernel/vdso/Makefile > > > index cb8f9e4cfcbf..0cfd6da784f8 100644 > > > --- a/arch/riscv/kernel/vdso/Makefile > > > +++ b/arch/riscv/kernel/vdso/Makefile > > > @@ -44,7 +44,7 @@ SYSCFLAGS_vdso.so.dbg = $(c_flags) > > > $(obj)/vdso.so.dbg: $(src)/vdso.lds $(obj-vdso) FORCE > > > $(call if_changed,vdsold) > > > SYSCFLAGS_vdso.so.dbg = -shared -s -Wl,-soname=linux-vdso.so.1 \ > > > - -Wl,--build-id -Wl,--hash-style=both > > > + -Wl,--build-id=sha1 -Wl,--hash-style=both > > > > > > # We also create a special relocatable object that should mirror the symbol > > > # table and layout of the linked DSO. With ld --just-symbols we can then > > > > > > base-commit: c2c81bb2f69138f902e1a58d3bef6ad97fb8a92c > > > -- > > > 2.29.2 > > > > > > -- > > > You received this message because you are subscribed to the Google Groups "Clang Built Linux" group. > > > To unsubscribe from this group and stop receiving emails from it, send an email to clang-built-linux+unsubscribe@googlegroups.com. > > > To view this discussion on the web visit https://groups.google.com/d/msgid/clang-built-linux/20201108203737.94270-1-natechancellor%40gmail.com. > > > > > > > > -- > > Thanks, > > ~Nick Desaulniers
On Sun, 08 Nov 2020 12:37:37 PST (-0800), natechancellor@gmail.com wrote: > Commit a96843372331 ("kbuild: explicitly specify the build id style") > explicitly set the build ID style to SHA1. Commit c2c81bb2f691 ("RISC-V: > Fix the VDSO symbol generaton for binutils-2.35+") undid this change, > likely unintentionally. > > Restore it so that the build ID style stays consistent across the tree > regardless of linker. > > Fixes: c2c81bb2f691 ("RISC-V: Fix the VDSO symbol generaton for binutils-2.35+") > Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> > --- > arch/riscv/kernel/vdso/Makefile | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/riscv/kernel/vdso/Makefile b/arch/riscv/kernel/vdso/Makefile > index cb8f9e4cfcbf..0cfd6da784f8 100644 > --- a/arch/riscv/kernel/vdso/Makefile > +++ b/arch/riscv/kernel/vdso/Makefile > @@ -44,7 +44,7 @@ SYSCFLAGS_vdso.so.dbg = $(c_flags) > $(obj)/vdso.so.dbg: $(src)/vdso.lds $(obj-vdso) FORCE > $(call if_changed,vdsold) > SYSCFLAGS_vdso.so.dbg = -shared -s -Wl,-soname=linux-vdso.so.1 \ > - -Wl,--build-id -Wl,--hash-style=both > + -Wl,--build-id=sha1 -Wl,--hash-style=both > > # We also create a special relocatable object that should mirror the symbol > # table and layout of the linked DSO. With ld --just-symbols we can then > > base-commit: c2c81bb2f69138f902e1a58d3bef6ad97fb8a92c Sorry about that. This is on fixes.
diff --git a/arch/riscv/kernel/vdso/Makefile b/arch/riscv/kernel/vdso/Makefile index cb8f9e4cfcbf..0cfd6da784f8 100644 --- a/arch/riscv/kernel/vdso/Makefile +++ b/arch/riscv/kernel/vdso/Makefile @@ -44,7 +44,7 @@ SYSCFLAGS_vdso.so.dbg = $(c_flags) $(obj)/vdso.so.dbg: $(src)/vdso.lds $(obj-vdso) FORCE $(call if_changed,vdsold) SYSCFLAGS_vdso.so.dbg = -shared -s -Wl,-soname=linux-vdso.so.1 \ - -Wl,--build-id -Wl,--hash-style=both + -Wl,--build-id=sha1 -Wl,--hash-style=both # We also create a special relocatable object that should mirror the symbol # table and layout of the linked DSO. With ld --just-symbols we can then
Commit a96843372331 ("kbuild: explicitly specify the build id style") explicitly set the build ID style to SHA1. Commit c2c81bb2f691 ("RISC-V: Fix the VDSO symbol generaton for binutils-2.35+") undid this change, likely unintentionally. Restore it so that the build ID style stays consistent across the tree regardless of linker. Fixes: c2c81bb2f691 ("RISC-V: Fix the VDSO symbol generaton for binutils-2.35+") Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> --- arch/riscv/kernel/vdso/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) base-commit: c2c81bb2f69138f902e1a58d3bef6ad97fb8a92c