Re: [PATCH] powerpc/build: vdso linker warning for orphan sections
Hi Michael,
On 2023-07-19, Michael Ellerman wrote:
> I regularly test with a gcc 5.5.0 / ld 2.29 toolchain and gcc 13.1.1 /
> ld 2.39, and I haven't seen the warning. I tried a bunch of others and
> can't reproduce it.
I will send my config in a separate email (without the lists in
CC). Building the vdso_prepare target is all that is needed.
> Can you confirm that this makes the warning go away?
>
> diff --git a/arch/powerpc/kernel/vdso/vdso64.lds.S
> b/arch/powerpc/kernel/vdso/vdso64.lds.S
> index bda6c8cdd459..286e1597c548 100644
> --- a/arch/powerpc/kernel/vdso/vdso64.lds.S
> +++ b/arch/powerpc/kernel/vdso/vdso64.lds.S
> @@ -85,7 +85,7 @@ SECTIONS
> *(.branch_lt)
> *(.data .data.* .gnu.linkonce.d.* .sdata*)
> *(.bss .sbss .dynbss .dynsbss)
> - *(.opd)
> + *(.opd .rela.opd)
> *(.glink .iplt .plt .rela*)
Hmmm. Not sure what that would change. And indeed it does not make the
warning go away.
Doing some testing it seems that previously .rela.opd was being silently
placed in the .rela.dyn section. So doing that explicitly obviously gets
rid of the warning:
Index: linux-6.5-rc2/arch/powerpc/kernel/vdso/vdso64.lds.S
===
--- linux-6.5-rc2.orig/arch/powerpc/kernel/vdso/vdso64.lds.S
+++ linux-6.5-rc2/arch/powerpc/kernel/vdso/vdso64.lds.S
@@ -69,7 +69,7 @@ SECTIONS
.eh_frame_hdr : { *(.eh_frame_hdr) } :text :eh_frame_hdr
.eh_frame : { KEEP (*(.eh_frame)) } :text
.gcc_except_table : { *(.gcc_except_table) }
- .rela.dyn ALIGN(8) : { *(.rela.dyn) }
+ .rela.dyn ALIGN(8) : { *(.rela.dyn) *(.rela.opd) }
.got ALIGN(8) : { *(.got .toc) }
But if the goal is to get rid of .rela.opd then the question is: why is
the linker complaining about it being discarded?
John
Re: [PATCH] powerpc/build: vdso linker warning for orphan sections
John Ogness writes:
> On 2023-07-18, Michael Ellerman wrote:
>>> ld: warning: discarding dynamic section .rela.opd
>>>
>>> and bisects to:
>>>
>>> 8ad57add77d3 ("powerpc/build: vdso linker warning for orphan sections")
>>
>> Can you test with a newer compiler/binutils?
>
> Testing the Debian release cross compilers/binutils:
>
> Debian 10 / gcc 8.3.0 / ld 2.31.1: generates the warning
>
> Debian 11 / gcc 10.2.1 / ld 2.35.2: generates the warning
>
> Debian 12 / gcc 12.2.0 / ld 2.40: does _not_ generate the warning
>
> I suppose moving to the newer toolchain is the workaround. Although it
> is a bit unusual to require such a modern toolchain in order to build a
> kernel without warnings.
I didn't mean that you should move to a new toolchain to avoid the
warning, I was just curious why you're the only person to see it.
I regularly test with a gcc 5.5.0 / ld 2.29 toolchain and gcc 13.1.1 /
ld 2.39, and I haven't seen the warning. I tried a bunch of others and
can't reproduce it.
Can you confirm that this makes the warning go away?
cheers
diff --git a/arch/powerpc/kernel/vdso/vdso64.lds.S
b/arch/powerpc/kernel/vdso/vdso64.lds.S
index bda6c8cdd459..286e1597c548 100644
--- a/arch/powerpc/kernel/vdso/vdso64.lds.S
+++ b/arch/powerpc/kernel/vdso/vdso64.lds.S
@@ -85,7 +85,7 @@ SECTIONS
*(.branch_lt)
*(.data .data.* .gnu.linkonce.d.* .sdata*)
*(.bss .sbss .dynbss .dynsbss)
- *(.opd)
+ *(.opd .rela.opd)
*(.glink .iplt .plt .rela*)
}
}
Re: [PATCH] powerpc/build: vdso linker warning for orphan sections
On 2023-07-18, Michael Ellerman wrote:
>> ld: warning: discarding dynamic section .rela.opd
>>
>> and bisects to:
>>
>> 8ad57add77d3 ("powerpc/build: vdso linker warning for orphan sections")
>
> Can you test with a newer compiler/binutils?
Testing the Debian release cross compilers/binutils:
Debian 10 / gcc 8.3.0 / ld 2.31.1: generates the warning
Debian 11 / gcc 10.2.1 / ld 2.35.2: generates the warning
Debian 12 / gcc 12.2.0 / ld 2.40: does _not_ generate the warning
I suppose moving to the newer toolchain is the workaround. Although it
is a bit unusual to require such a modern toolchain in order to build a
kernel without warnings.
John Ogness
Re: [PATCH] powerpc/build: vdso linker warning for orphan sections
John Ogness writes:
> Hi Nicholas,
>
> On 2023-06-09, Nicholas Piggin wrote:
>> Add --orphan-handlin for vdsos, and adjust vdso linker scripts to deal
>> with orphan sections.
>
> I'm reporting that I am getting a linker warning with 6.5-rc2. The
> warning message is:
>
> ld: warning: discarding dynamic section .rela.opd
>
> and bisects to:
>
> 8ad57add77d3 ("powerpc/build: vdso linker warning for orphan sections")
>
> Despite the warning, my ppc64 system seems to run fine. Let me know if
> you need any other information from me.
We already discard .opd and .rela*, so I guess we should also be
discarding .rela.opd.
Can you test with a newer compiler/binutils?
cheers
Re: [PATCH] powerpc/build: vdso linker warning for orphan sections
Hi Nicholas,
On 2023-06-09, Nicholas Piggin wrote:
> Add --orphan-handlin for vdsos, and adjust vdso linker scripts to deal
> with orphan sections.
I'm reporting that I am getting a linker warning with 6.5-rc2. The
warning message is:
ld: warning: discarding dynamic section .rela.opd
and bisects to:
8ad57add77d3 ("powerpc/build: vdso linker warning for orphan sections")
Despite the warning, my ppc64 system seems to run fine. Let me know if
you need any other information from me.
I noticed [0] this with 6.5-rc1 but didn't contact the right people.
John Ogness
[0] https://lore.kernel.org/lkml/871qhf1q3j@jogness.linutronix.de
Re: [PATCH] powerpc/build: vdso linker warning for orphan sections
On Fri, 09 Jun 2023 15:10:02 +1000, Nicholas Piggin wrote: > Add --orphan-handlin for vdsos, and adjust vdso linker scripts to deal > with orphan sections. > > Applied to powerpc/next. [1/1] powerpc/build: vdso linker warning for orphan sections https://git.kernel.org/powerpc/c/8ad57add77d352102ba9edd500b00bc851c2e261 cheers
[PATCH] powerpc/build: vdso linker warning for orphan sections
Add --orphan-handlin for vdsos, and adjust vdso linker scripts to deal
with orphan sections.
Signed-off-by: Nicholas Piggin
---
arch/powerpc/kernel/vdso/Makefile | 2 ++
arch/powerpc/kernel/vdso/vdso32.lds.S | 4 +++-
arch/powerpc/kernel/vdso/vdso64.lds.S | 4 +++-
3 files changed, 8 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/kernel/vdso/Makefile
b/arch/powerpc/kernel/vdso/Makefile
index 4c3f34485f08..23ee96106537 100644
--- a/arch/powerpc/kernel/vdso/Makefile
+++ b/arch/powerpc/kernel/vdso/Makefile
@@ -56,6 +56,8 @@ KCSAN_SANITIZE := n
ccflags-y := -fno-common -fno-builtin
ldflags-y := -Wl,--hash-style=both -nostdlib -shared -z noexecstack
ldflags-$(CONFIG_LD_IS_LLD) += $(call cc-option,--ld-path=$(LD),-fuse-ld=lld)
+ldflags-$(CONFIG_LD_ORPHAN_WARN) +=
-Wl,--orphan-handling=$(CONFIG_LD_ORPHAN_WARN_LEVEL)
+
# Filter flags that clang will warn are unused for linking
ldflags-y += $(filter-out $(CC_AUTO_VAR_INIT_ZERO_ENABLER) $(CC_FLAGS_FTRACE)
-Wa$(comma)%, $(KBUILD_CFLAGS))
diff --git a/arch/powerpc/kernel/vdso/vdso32.lds.S
b/arch/powerpc/kernel/vdso/vdso32.lds.S
index bc0be274a9ac..426e1ccc6971 100644
--- a/arch/powerpc/kernel/vdso/vdso32.lds.S
+++ b/arch/powerpc/kernel/vdso/vdso32.lds.S
@@ -83,9 +83,11 @@ SECTIONS
/DISCARD/ : {
*(.note.GNU-stack)
+ *(*.EMB.apuinfo)
+ *(.branch_lt)
*(.data .data.* .gnu.linkonce.d.* .sdata*)
*(.bss .sbss .dynbss .dynsbss)
- *(.got1)
+ *(.got1 .glink .iplt .rela*)
}
}
diff --git a/arch/powerpc/kernel/vdso/vdso64.lds.S
b/arch/powerpc/kernel/vdso/vdso64.lds.S
index 744ae5363e6c..bda6c8cdd459 100644
--- a/arch/powerpc/kernel/vdso/vdso64.lds.S
+++ b/arch/powerpc/kernel/vdso/vdso64.lds.S
@@ -32,7 +32,7 @@ SECTIONS
. = ALIGN(16);
.text : {
*(.text .stub .text.* .gnu.linkonce.t.* __ftr_alt_*)
- *(.sfpr .glink)
+ *(.sfpr)
} :text
PROVIDE(__etext = .);
PROVIDE(_etext = .);
@@ -81,10 +81,12 @@ SECTIONS
/DISCARD/ : {
*(.note.GNU-stack)
+ *(*.EMB.apuinfo)
*(.branch_lt)
*(.data .data.* .gnu.linkonce.d.* .sdata*)
*(.bss .sbss .dynbss .dynsbss)
*(.opd)
+ *(.glink .iplt .plt .rela*)
}
}
--
2.40.1
Re: [PATCH] powerpc/build: vdso linker warning for orphan sections
Excerpts from Nicholas Piggin's message of June 11, 2021 9:10 pm: > Add --orphan-handling=warn for vdsos, and adjust vdso linker scripts to > deal with orphan sections. > > Signed-off-by: Nicholas Piggin Okay it looks like modules should discard .PPC.EMB.apuinfo. Not entirely sure about .rela.opd. Thanks, Nick
[PATCH] powerpc/build: vdso linker warning for orphan sections
Add --orphan-handling=warn for vdsos, and adjust vdso linker scripts to
deal with orphan sections.
Signed-off-by: Nicholas Piggin
---
arch/powerpc/kernel/vdso32/Makefile | 2 +-
arch/powerpc/kernel/vdso32/vdso32.lds.S | 3 ++-
arch/powerpc/kernel/vdso64/Makefile | 2 +-
arch/powerpc/kernel/vdso64/vdso64.lds.S | 3 ++-
4 files changed, 6 insertions(+), 4 deletions(-)
diff --git a/arch/powerpc/kernel/vdso32/Makefile
b/arch/powerpc/kernel/vdso32/Makefile
index 7d9a6fee0e3d..403033013848 100644
--- a/arch/powerpc/kernel/vdso32/Makefile
+++ b/arch/powerpc/kernel/vdso32/Makefile
@@ -66,7 +66,7 @@ include/generated/vdso32-offsets.h: $(obj)/vdso32.so.dbg FORCE
# actual build commands
quiet_cmd_vdso32ld_and_check = VDSO32L $@
- cmd_vdso32ld_and_check = $(VDSOCC) $(c_flags) $(CC32FLAGS) -o $@
-Wl,-T$(filter %.lds,$^) $(filter %.o,$^) ; $(cmd_vdso_check)
+ cmd_vdso32ld_and_check = $(VDSOCC) $(c_flags) $(CC32FLAGS) -o $@
-Wl,-T$(filter %.lds,$^) $(filter %.o,$^) $(if $(CONFIG_LD_ORPHAN_WARN),
-Wl$(comma)--orphan-handling=warn) ; $(cmd_vdso_check)
quiet_cmd_vdso32as = VDSO32A $@
cmd_vdso32as = $(VDSOCC) $(a_flags) $(CC32FLAGS) -c -o $@ $<
quiet_cmd_vdso32cc = VDSO32C $@
diff --git a/arch/powerpc/kernel/vdso32/vdso32.lds.S
b/arch/powerpc/kernel/vdso32/vdso32.lds.S
index 58e0099f70f4..b42e8759e67a 100644
--- a/arch/powerpc/kernel/vdso32/vdso32.lds.S
+++ b/arch/powerpc/kernel/vdso32/vdso32.lds.S
@@ -85,9 +85,10 @@ SECTIONS
/DISCARD/ : {
*(.note.GNU-stack)
+ *(.branch_lt)
*(.data .data.* .gnu.linkonce.d.* .sdata*)
*(.bss .sbss .dynbss .dynsbss)
- *(.got1)
+ *(.got1 .glink .iplt .rela*)
}
}
diff --git a/arch/powerpc/kernel/vdso64/Makefile
b/arch/powerpc/kernel/vdso64/Makefile
index d783c07e558f..980dfd631a08 100644
--- a/arch/powerpc/kernel/vdso64/Makefile
+++ b/arch/powerpc/kernel/vdso64/Makefile
@@ -59,4 +59,4 @@ include/generated/vdso64-offsets.h: $(obj)/vdso64.so.dbg FORCE
# actual build commands
quiet_cmd_vdso64ld_and_check = VDSO64L $@
- cmd_vdso64ld_and_check = $(CC) $(c_flags) -o $@ -Wl,-T$(filter %.lds,$^)
$(filter %.o,$^); $(cmd_vdso_check)
+ cmd_vdso64ld_and_check = $(CC) $(c_flags) -o $@ -Wl,-T$(filter %.lds,$^)
$(filter %.o,$^) $(if $(CONFIG_LD_ORPHAN_WARN),
-Wl$(comma)--orphan-handling=warn) ; $(cmd_vdso_check)
diff --git a/arch/powerpc/kernel/vdso64/vdso64.lds.S
b/arch/powerpc/kernel/vdso64/vdso64.lds.S
index 0288cad428b0..3750b3b15b51 100644
--- a/arch/powerpc/kernel/vdso64/vdso64.lds.S
+++ b/arch/powerpc/kernel/vdso64/vdso64.lds.S
@@ -33,7 +33,7 @@ SECTIONS
. = ALIGN(16);
.text : {
*(.text .stub .text.* .gnu.linkonce.t.* __ftr_alt_*)
- *(.sfpr .glink)
+ *(.sfpr)
} :text
PROVIDE(__etext = .);
PROVIDE(_etext = .);
@@ -87,6 +87,7 @@ SECTIONS
*(.data .data.* .gnu.linkonce.d.* .sdata*)
*(.bss .sbss .dynbss .dynsbss)
*(.opd)
+ *(.glink .iplt .plt .rela*)
}
}
--
2.23.0
Re: [PATCH] powerpc/build: vdso linker warning for orphan sections
On Tue, 3 Mar 2020 11:27:48 +1000, Nicholas Piggin wrote: > Applied to powerpc/next. [1/1] powerpc/build: vdso linker warning for orphan sections https://git.kernel.org/powerpc/c/f2af201002a8bc22500c04cc474ea480bf361351 cheers
[PATCH] powerpc/build: vdso linker warning for orphan sections
Signed-off-by: Nicholas Piggin
---
arch/powerpc/kernel/vdso32/Makefile | 2 +-
arch/powerpc/kernel/vdso32/vdso32.lds.S | 1 +
arch/powerpc/kernel/vdso64/Makefile | 2 +-
arch/powerpc/kernel/vdso64/vdso64.lds.S | 3 ++-
4 files changed, 5 insertions(+), 3 deletions(-)
diff --git a/arch/powerpc/kernel/vdso32/Makefile
b/arch/powerpc/kernel/vdso32/Makefile
index e147bbdc12cd..87ab1152d5ce 100644
--- a/arch/powerpc/kernel/vdso32/Makefile
+++ b/arch/powerpc/kernel/vdso32/Makefile
@@ -50,7 +50,7 @@ $(obj-vdso32): %.o: %.S FORCE
# actual build commands
quiet_cmd_vdso32ld = VDSO32L $@
- cmd_vdso32ld = $(VDSOCC) $(c_flags) $(CC32FLAGS) -o $@ -Wl,-T$(filter
%.lds,$^) $(filter %.o,$^)
+ cmd_vdso32ld = $(VDSOCC) $(c_flags) $(CC32FLAGS) -o $@ $(call
cc-ldoption, -Wl$(comma)--orphan-handling=warn) -Wl,-T$(filter %.lds,$^)
$(filter %.o,$^)
quiet_cmd_vdso32as = VDSO32A $@
cmd_vdso32as = $(VDSOCC) $(a_flags) $(CC32FLAGS) -c -o $@ $<
diff --git a/arch/powerpc/kernel/vdso32/vdso32.lds.S
b/arch/powerpc/kernel/vdso32/vdso32.lds.S
index 5206c2eb2a1d..4c985467a668 100644
--- a/arch/powerpc/kernel/vdso32/vdso32.lds.S
+++ b/arch/powerpc/kernel/vdso32/vdso32.lds.S
@@ -111,6 +111,7 @@ SECTIONS
*(.note.GNU-stack)
*(.data .data.* .gnu.linkonce.d.* .sdata*)
*(.bss .sbss .dynbss .dynsbss)
+ *(.glink .iplt .plt .rela*)
}
}
diff --git a/arch/powerpc/kernel/vdso64/Makefile
b/arch/powerpc/kernel/vdso64/Makefile
index 32ebb3522ea1..38c317f25141 100644
--- a/arch/powerpc/kernel/vdso64/Makefile
+++ b/arch/powerpc/kernel/vdso64/Makefile
@@ -34,7 +34,7 @@ $(obj)/%.so: $(obj)/%.so.dbg FORCE
# actual build commands
quiet_cmd_vdso64ld = VDSO64L $@
- cmd_vdso64ld = $(CC) $(c_flags) -o $@ -Wl,-T$(filter %.lds,$^) $(filter
%.o,$^)
+ cmd_vdso64ld = $(CC) $(c_flags) -o $@ -Wl,-T$(filter %.lds,$^) $(filter
%.o,$^) $(call cc-ldoption, -Wl$(comma)--orphan-handling=warn)
# install commands for the unstripped file
quiet_cmd_vdso_install = INSTALL $@
diff --git a/arch/powerpc/kernel/vdso64/vdso64.lds.S
b/arch/powerpc/kernel/vdso64/vdso64.lds.S
index 256fb9720298..4e3a8d4ee614 100644
--- a/arch/powerpc/kernel/vdso64/vdso64.lds.S
+++ b/arch/powerpc/kernel/vdso64/vdso64.lds.S
@@ -30,7 +30,7 @@ SECTIONS
. = ALIGN(16);
.text : {
*(.text .stub .text.* .gnu.linkonce.t.* __ftr_alt_*)
- *(.sfpr .glink)
+ *(.sfpr)
} :text
PROVIDE(__etext = .);
PROVIDE(_etext = .);
@@ -111,6 +111,7 @@ SECTIONS
*(.branch_lt)
*(.data .data.* .gnu.linkonce.d.* .sdata*)
*(.bss .sbss .dynbss .dynsbss)
+ *(.glink .iplt .plt .rela*)
}
}
--
2.23.0
