* [PATCH v4 mips-next 0/7] MIPS: vmlinux.lds.S sections fixes & cleanup
@ 2021-01-07 12:33 Alexander Lobakin
2021-01-07 12:34 ` [PATCH v4 mips-next 1/7] MIPS: vmlinux.lds.S: add missing PAGE_ALIGNED_DATA() section Alexander Lobakin
` (3 more replies)
0 siblings, 4 replies; 22+ messages in thread
From: Alexander Lobakin @ 2021-01-07 12:33 UTC (permalink / raw)
To: Thomas Bogendoerfer
Cc: Arnd Bergmann, Kees Cook, Nathan Chancellor, Nick Desaulniers,
Fangrui Song, Huacai Chen, Pei Huang, Jiaxun Yang,
Alexander Lobakin, Sami Tolvanen, Ingo Molnar, Ralf Baechle,
Corey Minyard, linux-mips, linux-kernel, linux-arch, stable,
clang-built-linux
This series hunts the problems discovered after manual enabling of
ARCH_WANT_LD_ORPHAN_WARN. Notably:
- adds the missing PAGE_ALIGNED_DATA() section affecting VDSO
placement (marked for stable);
- properly stops .eh_frame section generation.
Compile and runtime tested on MIPS32R2 CPS board with no issues
using two different toolkits:
- Binutils 2.35.1, GCC 10.2.0;
- LLVM stack 11.0.0.
Since v3 [2]:
- fix the third patch as GNU stack emits .rel.dyn into VDSO for
some reason if .cfi_sections is specified.
Since v2 [1]:
- stop discarding .eh_frame and just prevent it from generating
(Kees);
- drop redundant sections assertions (Fangrui);
- place GOT table in .text instead of asserting as it's not empty
when building with LLVM (Nathan);
- catch compound literals in generic definitions when building with
LD_DEAD_CODE_DATA_ELIMINATION (Kees);
- collect two Reviewed-bys (Kees).
Since v1 [0]:
- catch .got entries too as LLD may produce it (Nathan);
- check for unwanted sections to be zero-sized instead of
discarding (Fangrui).
[0] https://lore.kernel.org/linux-mips/20210104121729.46981-1-alobakin@pm.me
[1] https://lore.kernel.org/linux-mips/20210106200713.31840-1-alobakin@pm.me
[2] https://lore.kernel.org/linux-mips/20210107115120.281008-1-alobakin@pm.me
Alexander Lobakin (7):
MIPS: vmlinux.lds.S: add missing PAGE_ALIGNED_DATA() section
MIPS: vmlinux.lds.S: add ".gnu.attributes" to DISCARDS
MIPS: properly stop .eh_frame generation
MIPS: vmlinux.lds.S: catch bad .rel.dyn at link time
MIPS: vmlinux.lds.S: explicitly declare .got table
vmlinux.lds.h: catch compound literals into data and BSS
MIPS: select ARCH_WANT_LD_ORPHAN_WARN
arch/mips/Kconfig | 1 +
arch/mips/include/asm/asm.h | 18 ++++++++++++++++++
arch/mips/kernel/vmlinux.lds.S | 15 ++++++++++++++-
include/asm-generic/vmlinux.lds.h | 6 +++---
4 files changed, 36 insertions(+), 4 deletions(-)
--
2.30.0
^ permalink raw reply [flat|nested] 22+ messages in thread
* [PATCH v4 mips-next 1/7] MIPS: vmlinux.lds.S: add missing PAGE_ALIGNED_DATA() section
2021-01-07 12:33 [PATCH v4 mips-next 0/7] MIPS: vmlinux.lds.S sections fixes & cleanup Alexander Lobakin
@ 2021-01-07 12:34 ` Alexander Lobakin
2021-01-07 12:34 ` [PATCH v4 mips-next 2/7] MIPS: vmlinux.lds.S: add ".gnu.attributes" to DISCARDS Alexander Lobakin
` (2 more replies)
2021-01-07 13:20 ` [PATCH v4 mips-next 4/7] MIPS: vmlinux.lds.S: catch bad .rel.dyn at link time Alexander Lobakin
` (2 subsequent siblings)
3 siblings, 3 replies; 22+ messages in thread
From: Alexander Lobakin @ 2021-01-07 12:34 UTC (permalink / raw)
To: Thomas Bogendoerfer
Cc: Arnd Bergmann, Kees Cook, Nathan Chancellor, Nick Desaulniers,
Fangrui Song, Huacai Chen, Pei Huang, Jiaxun Yang,
Alexander Lobakin, Sami Tolvanen, Ingo Molnar, Ralf Baechle,
Corey Minyard, linux-mips, linux-kernel, linux-arch, stable,
clang-built-linux
MIPS uses its own declaration of rwdata, and thus it should be kept
in sync with the asm-generic one. Currently PAGE_ALIGNED_DATA() is
missing from the linker script, which emits the following ld
warnings:
mips-alpine-linux-musl-ld: warning: orphan section
`.data..page_aligned' from `arch/mips/kernel/vdso.o' being placed
in section `.data..page_aligned'
mips-alpine-linux-musl-ld: warning: orphan section
`.data..page_aligned' from `arch/mips/vdso/vdso-image.o' being placed
in section `.data..page_aligned'
Add the necessary declaration, so the mentioned structures will be
placed in vmlinux as intended:
ffffffff80630580 D __end_once
ffffffff80630580 D __start___dyndbg
ffffffff80630580 D __start_once
ffffffff80630580 D __stop___dyndbg
ffffffff80634000 d mips_vdso_data
ffffffff80638000 d vdso_data
ffffffff80638580 D _gp
ffffffff8063c000 T __init_begin
ffffffff8063c000 D _edata
ffffffff8063c000 T _sinittext
->
ffffffff805a4000 D __end_init_task
ffffffff805a4000 D __nosave_begin
ffffffff805a4000 D __nosave_end
ffffffff805a4000 d mips_vdso_data
ffffffff805a8000 d vdso_data
ffffffff805ac000 D mmlist_lock
ffffffff805ac080 D tasklist_lock
Fixes: ebb5e78cc634 ("MIPS: Initial implementation of a VDSO")
Cc: stable@vger.kernel.org # 4.4+
Signed-off-by: Alexander Lobakin <alobakin@pm.me>
Reviewed-by: Kees Cook <keescook@chromium.org>
---
arch/mips/kernel/vmlinux.lds.S | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/mips/kernel/vmlinux.lds.S b/arch/mips/kernel/vmlinux.lds.S
index 5e97e9d02f98..83e27a181206 100644
--- a/arch/mips/kernel/vmlinux.lds.S
+++ b/arch/mips/kernel/vmlinux.lds.S
@@ -90,6 +90,7 @@ SECTIONS
INIT_TASK_DATA(THREAD_SIZE)
NOSAVE_DATA
+ PAGE_ALIGNED_DATA(PAGE_SIZE)
CACHELINE_ALIGNED_DATA(1 << CONFIG_MIPS_L1_CACHE_SHIFT)
READ_MOSTLY_DATA(1 << CONFIG_MIPS_L1_CACHE_SHIFT)
DATA_DATA
--
2.30.0
^ permalink raw reply related [flat|nested] 22+ messages in thread
* [PATCH v4 mips-next 2/7] MIPS: vmlinux.lds.S: add ".gnu.attributes" to DISCARDS
2021-01-07 12:34 ` [PATCH v4 mips-next 1/7] MIPS: vmlinux.lds.S: add missing PAGE_ALIGNED_DATA() section Alexander Lobakin
@ 2021-01-07 12:34 ` Alexander Lobakin
2021-01-08 21:12 ` Nathan Chancellor
2021-01-07 12:35 ` [PATCH v4 mips-next 3/7] MIPS: properly stop .eh_frame generation Alexander Lobakin
2021-01-08 21:10 ` [PATCH v4 mips-next 1/7] MIPS: vmlinux.lds.S: add missing PAGE_ALIGNED_DATA() section Nathan Chancellor
2 siblings, 1 reply; 22+ messages in thread
From: Alexander Lobakin @ 2021-01-07 12:34 UTC (permalink / raw)
To: Thomas Bogendoerfer
Cc: Arnd Bergmann, Kees Cook, Nathan Chancellor, Nick Desaulniers,
Fangrui Song, Huacai Chen, Pei Huang, Jiaxun Yang,
Alexander Lobakin, Sami Tolvanen, Ingo Molnar, Ralf Baechle,
Corey Minyard, linux-mips, linux-kernel, linux-arch, stable,
clang-built-linux
Discard GNU attributes (MIPS FP type, GNU Hash etc.) at link time
as kernel doesn't use it at all.
Solves a dozen of the following ld warnings (one per every file):
mips-alpine-linux-musl-ld: warning: orphan section `.gnu.attributes'
from `arch/mips/kernel/head.o' being placed in section
`.gnu.attributes'
mips-alpine-linux-musl-ld: warning: orphan section `.gnu.attributes'
from `init/main.o' being placed in section `.gnu.attributes'
Signed-off-by: Alexander Lobakin <alobakin@pm.me>
---
arch/mips/kernel/vmlinux.lds.S | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/mips/kernel/vmlinux.lds.S b/arch/mips/kernel/vmlinux.lds.S
index 83e27a181206..16468957cba2 100644
--- a/arch/mips/kernel/vmlinux.lds.S
+++ b/arch/mips/kernel/vmlinux.lds.S
@@ -221,6 +221,7 @@ SECTIONS
/* ABI crap starts here */
*(.MIPS.abiflags)
*(.MIPS.options)
+ *(.gnu.attributes)
*(.options)
*(.pdr)
*(.reginfo)
--
2.30.0
^ permalink raw reply related [flat|nested] 22+ messages in thread
* [PATCH v4 mips-next 3/7] MIPS: properly stop .eh_frame generation
2021-01-07 12:34 ` [PATCH v4 mips-next 1/7] MIPS: vmlinux.lds.S: add missing PAGE_ALIGNED_DATA() section Alexander Lobakin
2021-01-07 12:34 ` [PATCH v4 mips-next 2/7] MIPS: vmlinux.lds.S: add ".gnu.attributes" to DISCARDS Alexander Lobakin
@ 2021-01-07 12:35 ` Alexander Lobakin
2021-01-07 21:48 ` Kees Cook
2021-01-08 21:16 ` Nathan Chancellor
2021-01-08 21:10 ` [PATCH v4 mips-next 1/7] MIPS: vmlinux.lds.S: add missing PAGE_ALIGNED_DATA() section Nathan Chancellor
2 siblings, 2 replies; 22+ messages in thread
From: Alexander Lobakin @ 2021-01-07 12:35 UTC (permalink / raw)
To: Thomas Bogendoerfer
Cc: Arnd Bergmann, Kees Cook, Nathan Chancellor, Nick Desaulniers,
Fangrui Song, Huacai Chen, Pei Huang, Jiaxun Yang,
Alexander Lobakin, Sami Tolvanen, Ingo Molnar, Ralf Baechle,
Corey Minyard, linux-mips, linux-kernel, linux-arch, stable,
clang-built-linux
Commit 866b6a89c6d1 ("MIPS: Add DWARF unwinding to assembly") added
-fno-asynchronous-unwind-tables to KBUILD_CFLAGS to prevent compiler
from emitting .eh_frame symbols.
However, as MIPS heavily uses CFI, that's not enough. Use the
approach taken for x86 (as it also uses CFI) and explicitly put CFI
symbols into the .debug_frame section (except for VDSO).
This allows us to drop .eh_frame from DISCARDS as it's no longer
being generated.
Fixes: 866b6a89c6d1 ("MIPS: Add DWARF unwinding to assembly")
Suggested-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Alexander Lobakin <alobakin@pm.me>
---
arch/mips/include/asm/asm.h | 18 ++++++++++++++++++
arch/mips/kernel/vmlinux.lds.S | 1 -
2 files changed, 18 insertions(+), 1 deletion(-)
diff --git a/arch/mips/include/asm/asm.h b/arch/mips/include/asm/asm.h
index 3682d1a0bb80..908f6d6ae24b 100644
--- a/arch/mips/include/asm/asm.h
+++ b/arch/mips/include/asm/asm.h
@@ -20,10 +20,27 @@
#include <asm/sgidefs.h>
#include <asm/asm-eva.h>
+#ifndef __VDSO__
+/*
+ * Emit CFI data in .debug_frame sections, not .eh_frame sections.
+ * We don't do DWARF unwinding at runtime, so only the offline DWARF
+ * information is useful to anyone. Note we should change this if we
+ * ever decide to enable DWARF unwinding at runtime.
+ */
+#define CFI_SECTIONS .cfi_sections .debug_frame
+#else
+ /*
+ * For the vDSO, emit both runtime unwind information and debug
+ * symbols for the .dbg file.
+ */
+#define CFI_SECTIONS
+#endif
+
/*
* LEAF - declare leaf routine
*/
#define LEAF(symbol) \
+ CFI_SECTIONS; \
.globl symbol; \
.align 2; \
.type symbol, @function; \
@@ -36,6 +53,7 @@ symbol: .frame sp, 0, ra; \
* NESTED - declare nested routine entry point
*/
#define NESTED(symbol, framesize, rpc) \
+ CFI_SECTIONS; \
.globl symbol; \
.align 2; \
.type symbol, @function; \
diff --git a/arch/mips/kernel/vmlinux.lds.S b/arch/mips/kernel/vmlinux.lds.S
index 16468957cba2..0f4e46ea4458 100644
--- a/arch/mips/kernel/vmlinux.lds.S
+++ b/arch/mips/kernel/vmlinux.lds.S
@@ -225,6 +225,5 @@ SECTIONS
*(.options)
*(.pdr)
*(.reginfo)
- *(.eh_frame)
}
}
--
2.30.0
^ permalink raw reply related [flat|nested] 22+ messages in thread
* [PATCH v4 mips-next 4/7] MIPS: vmlinux.lds.S: catch bad .rel.dyn at link time
2021-01-07 12:33 [PATCH v4 mips-next 0/7] MIPS: vmlinux.lds.S sections fixes & cleanup Alexander Lobakin
2021-01-07 12:34 ` [PATCH v4 mips-next 1/7] MIPS: vmlinux.lds.S: add missing PAGE_ALIGNED_DATA() section Alexander Lobakin
@ 2021-01-07 13:20 ` Alexander Lobakin
2021-01-07 13:20 ` [PATCH v4 mips-next 5/7] MIPS: vmlinux.lds.S: explicitly declare .got table Alexander Lobakin
` (4 more replies)
2021-01-07 21:51 ` [PATCH v4 mips-next 0/7] MIPS: vmlinux.lds.S sections fixes & cleanup Kees Cook
2021-01-09 11:12 ` Thomas Bogendoerfer
3 siblings, 5 replies; 22+ messages in thread
From: Alexander Lobakin @ 2021-01-07 13:20 UTC (permalink / raw)
To: Thomas Bogendoerfer
Cc: Arnd Bergmann, Kees Cook, Nathan Chancellor, Nick Desaulniers,
Fangrui Song, Huacai Chen, Pei Huang, Jiaxun Yang,
Alexander Lobakin, Sami Tolvanen, Ingo Molnar, Ralf Baechle,
Corey Minyard, linux-mips, linux-kernel, linux-arch, stable,
clang-built-linux
Catch any symbols placed in .rel.dyn and check for these sections
to be zero-sized at link time.
Eliminates following ld warning:
mips-alpine-linux-musl-ld: warning: orphan section `.rel.dyn'
from `init/main.o' being placed in section `.rel.dyn'
Adopted from x86/kernel/vmlinux.lds.S.
Suggested-by: Fangrui Song <maskray@google.com>
Signed-off-by: Alexander Lobakin <alobakin@pm.me>
---
arch/mips/kernel/vmlinux.lds.S | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/arch/mips/kernel/vmlinux.lds.S b/arch/mips/kernel/vmlinux.lds.S
index 0f4e46ea4458..0f736d60d43e 100644
--- a/arch/mips/kernel/vmlinux.lds.S
+++ b/arch/mips/kernel/vmlinux.lds.S
@@ -226,4 +226,15 @@ SECTIONS
*(.pdr)
*(.reginfo)
}
+
+ /*
+ * Sections that should stay zero sized, which is safer to
+ * explicitly check instead of blindly discarding.
+ */
+
+ .rel.dyn : {
+ *(.rel.*)
+ *(.rel_*)
+ }
+ ASSERT(SIZEOF(.rel.dyn) == 0, "Unexpected run-time relocations (.rel) detected!")
}
--
2.30.0
^ permalink raw reply related [flat|nested] 22+ messages in thread
* [PATCH v4 mips-next 5/7] MIPS: vmlinux.lds.S: explicitly declare .got table
2021-01-07 13:20 ` [PATCH v4 mips-next 4/7] MIPS: vmlinux.lds.S: catch bad .rel.dyn at link time Alexander Lobakin
@ 2021-01-07 13:20 ` Alexander Lobakin
2021-01-07 21:49 ` Kees Cook
2021-01-08 21:17 ` Nathan Chancellor
2021-01-07 13:20 ` [PATCH v4 mips-next 6/7] vmlinux.lds.h: catch compound literals into data and BSS Alexander Lobakin
` (3 subsequent siblings)
4 siblings, 2 replies; 22+ messages in thread
From: Alexander Lobakin @ 2021-01-07 13:20 UTC (permalink / raw)
To: Thomas Bogendoerfer
Cc: Arnd Bergmann, Kees Cook, Nathan Chancellor, Nick Desaulniers,
Fangrui Song, Huacai Chen, Pei Huang, Jiaxun Yang,
Alexander Lobakin, Sami Tolvanen, Ingo Molnar, Ralf Baechle,
Corey Minyard, linux-mips, linux-kernel, linux-arch, stable,
clang-built-linux
LLVM stack generates GOT table when building the kernel:
ld.lld: warning: <internal>:(.got) is being placed in '.got'
According to the debug assertions, it's not zero-sized and thus
can't be handled the same way as .rel.dyn (like it's done for x86).
Use the ARM/ARM64 path here and place it at the end of .text section.
Reported-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Alexander Lobakin <alobakin@pm.me>
---
arch/mips/kernel/vmlinux.lds.S | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/mips/kernel/vmlinux.lds.S b/arch/mips/kernel/vmlinux.lds.S
index 0f736d60d43e..4709959f6985 100644
--- a/arch/mips/kernel/vmlinux.lds.S
+++ b/arch/mips/kernel/vmlinux.lds.S
@@ -69,6 +69,7 @@ SECTIONS
*(.text.*)
*(.fixup)
*(.gnu.warning)
+ *(.got)
} :text = 0
_etext = .; /* End of text section */
--
2.30.0
^ permalink raw reply related [flat|nested] 22+ messages in thread
* [PATCH v4 mips-next 6/7] vmlinux.lds.h: catch compound literals into data and BSS
2021-01-07 13:20 ` [PATCH v4 mips-next 4/7] MIPS: vmlinux.lds.S: catch bad .rel.dyn at link time Alexander Lobakin
2021-01-07 13:20 ` [PATCH v4 mips-next 5/7] MIPS: vmlinux.lds.S: explicitly declare .got table Alexander Lobakin
@ 2021-01-07 13:20 ` Alexander Lobakin
2021-01-07 21:51 ` Kees Cook
2021-01-08 21:19 ` Nathan Chancellor
2021-01-07 13:21 ` [PATCH v4 mips-next 7/7] MIPS: select ARCH_WANT_LD_ORPHAN_WARN Alexander Lobakin
` (2 subsequent siblings)
4 siblings, 2 replies; 22+ messages in thread
From: Alexander Lobakin @ 2021-01-07 13:20 UTC (permalink / raw)
To: Thomas Bogendoerfer
Cc: Arnd Bergmann, Kees Cook, Nathan Chancellor, Nick Desaulniers,
Fangrui Song, Huacai Chen, Pei Huang, Jiaxun Yang,
Alexander Lobakin, Sami Tolvanen, Ingo Molnar, Ralf Baechle,
Corey Minyard, linux-mips, linux-kernel, linux-arch, stable,
clang-built-linux
When building kernel with LD_DEAD_CODE_DATA_ELIMINATION, LLVM stack
generates separate sections for compound literals, just like in case
with enabled LTO [0]:
ld.lld: warning: drivers/built-in.a(mtd/nand/spi/gigadevice.o):
(.data..compoundliteral.14) is being placed in
'.data..compoundliteral.14'
ld.lld: warning: drivers/built-in.a(mtd/nand/spi/gigadevice.o):
(.data..compoundliteral.15) is being placed in
'.data..compoundliteral.15'
ld.lld: warning: drivers/built-in.a(mtd/nand/spi/gigadevice.o):
(.data..compoundliteral.16) is being placed in
'.data..compoundliteral.16'
ld.lld: warning: drivers/built-in.a(mtd/nand/spi/gigadevice.o):
(.data..compoundliteral.17) is being placed in
'.data..compoundliteral.17'
[...]
Handle this by adding the related sections to generic definitions
as suggested by Sami [0].
[0] https://lore.kernel.org/lkml/20201211184633.3213045-3-samitolvanen@google.com
Suggested-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Alexander Lobakin <alobakin@pm.me>
---
include/asm-generic/vmlinux.lds.h | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index b2b3d81b1535..5f2f5b1db84f 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -95,10 +95,10 @@
*/
#ifdef CONFIG_LD_DEAD_CODE_DATA_ELIMINATION
#define TEXT_MAIN .text .text.[0-9a-zA-Z_]*
-#define DATA_MAIN .data .data.[0-9a-zA-Z_]* .data..LPBX*
+#define DATA_MAIN .data .data.[0-9a-zA-Z_]* .data..L* .data..compoundliteral*
#define SDATA_MAIN .sdata .sdata.[0-9a-zA-Z_]*
-#define RODATA_MAIN .rodata .rodata.[0-9a-zA-Z_]*
-#define BSS_MAIN .bss .bss.[0-9a-zA-Z_]*
+#define RODATA_MAIN .rodata .rodata.[0-9a-zA-Z_]* .rodata..L*
+#define BSS_MAIN .bss .bss.[0-9a-zA-Z_]* .bss..compoundliteral*
#define SBSS_MAIN .sbss .sbss.[0-9a-zA-Z_]*
#else
#define TEXT_MAIN .text
--
2.30.0
^ permalink raw reply related [flat|nested] 22+ messages in thread
* [PATCH v4 mips-next 7/7] MIPS: select ARCH_WANT_LD_ORPHAN_WARN
2021-01-07 13:20 ` [PATCH v4 mips-next 4/7] MIPS: vmlinux.lds.S: catch bad .rel.dyn at link time Alexander Lobakin
2021-01-07 13:20 ` [PATCH v4 mips-next 5/7] MIPS: vmlinux.lds.S: explicitly declare .got table Alexander Lobakin
2021-01-07 13:20 ` [PATCH v4 mips-next 6/7] vmlinux.lds.h: catch compound literals into data and BSS Alexander Lobakin
@ 2021-01-07 13:21 ` Alexander Lobakin
2021-01-08 21:19 ` Nathan Chancellor
2021-01-07 21:48 ` [PATCH v4 mips-next 4/7] MIPS: vmlinux.lds.S: catch bad .rel.dyn at link time Kees Cook
2021-01-08 21:17 ` Nathan Chancellor
4 siblings, 1 reply; 22+ messages in thread
From: Alexander Lobakin @ 2021-01-07 13:21 UTC (permalink / raw)
To: Thomas Bogendoerfer
Cc: Arnd Bergmann, Kees Cook, Nathan Chancellor, Nick Desaulniers,
Fangrui Song, Huacai Chen, Pei Huang, Jiaxun Yang,
Alexander Lobakin, Sami Tolvanen, Ingo Molnar, Ralf Baechle,
Corey Minyard, linux-mips, linux-kernel, linux-arch, stable,
clang-built-linux
Now, after that all the sections are explicitly described and
declared in vmlinux.lds.S, we can enable ld orphan warnings to
prevent from missing any new sections in future.
Signed-off-by: Alexander Lobakin <alobakin@pm.me>
Reviewed-by: Kees Cook <keescook@chromium.org>
---
arch/mips/Kconfig | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index d68df1febd25..d3e64cc0932b 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -18,6 +18,7 @@ config MIPS
select ARCH_USE_QUEUED_SPINLOCKS
select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT if MMU
select ARCH_WANT_IPC_PARSE_VERSION
+ select ARCH_WANT_LD_ORPHAN_WARN
select BUILDTIME_TABLE_SORT
select CLONE_BACKWARDS
select CPU_NO_EFFICIENT_FFS if (TARGET_ISA_REV < 1)
--
2.30.0
^ permalink raw reply related [flat|nested] 22+ messages in thread
* Re: [PATCH v4 mips-next 3/7] MIPS: properly stop .eh_frame generation
2021-01-07 12:35 ` [PATCH v4 mips-next 3/7] MIPS: properly stop .eh_frame generation Alexander Lobakin
@ 2021-01-07 21:48 ` Kees Cook
2021-01-08 21:16 ` Nathan Chancellor
1 sibling, 0 replies; 22+ messages in thread
From: Kees Cook @ 2021-01-07 21:48 UTC (permalink / raw)
To: Alexander Lobakin
Cc: Thomas Bogendoerfer, Arnd Bergmann, Nathan Chancellor,
Nick Desaulniers, Fangrui Song, Huacai Chen, Pei Huang,
Jiaxun Yang, Sami Tolvanen, Ingo Molnar, Ralf Baechle,
Corey Minyard, linux-mips, linux-kernel, linux-arch, stable,
clang-built-linux
On Thu, Jan 07, 2021 at 12:35:01PM +0000, Alexander Lobakin wrote:
> Commit 866b6a89c6d1 ("MIPS: Add DWARF unwinding to assembly") added
> -fno-asynchronous-unwind-tables to KBUILD_CFLAGS to prevent compiler
> from emitting .eh_frame symbols.
> However, as MIPS heavily uses CFI, that's not enough. Use the
> approach taken for x86 (as it also uses CFI) and explicitly put CFI
> symbols into the .debug_frame section (except for VDSO).
> This allows us to drop .eh_frame from DISCARDS as it's no longer
> being generated.
>
> Fixes: 866b6a89c6d1 ("MIPS: Add DWARF unwinding to assembly")
> Suggested-by: Kees Cook <keescook@chromium.org>
> Signed-off-by: Alexander Lobakin <alobakin@pm.me>
Reviewed-by: Kees Cook <keescook@chromium.org>
--
Kees Cook
^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: [PATCH v4 mips-next 4/7] MIPS: vmlinux.lds.S: catch bad .rel.dyn at link time
2021-01-07 13:20 ` [PATCH v4 mips-next 4/7] MIPS: vmlinux.lds.S: catch bad .rel.dyn at link time Alexander Lobakin
` (2 preceding siblings ...)
2021-01-07 13:21 ` [PATCH v4 mips-next 7/7] MIPS: select ARCH_WANT_LD_ORPHAN_WARN Alexander Lobakin
@ 2021-01-07 21:48 ` Kees Cook
2021-01-08 21:17 ` Nathan Chancellor
4 siblings, 0 replies; 22+ messages in thread
From: Kees Cook @ 2021-01-07 21:48 UTC (permalink / raw)
To: Alexander Lobakin
Cc: Thomas Bogendoerfer, Arnd Bergmann, Nathan Chancellor,
Nick Desaulniers, Fangrui Song, Huacai Chen, Pei Huang,
Jiaxun Yang, Sami Tolvanen, Ingo Molnar, Ralf Baechle,
Corey Minyard, linux-mips, linux-kernel, linux-arch, stable,
clang-built-linux
On Thu, Jan 07, 2021 at 01:20:33PM +0000, Alexander Lobakin wrote:
> Catch any symbols placed in .rel.dyn and check for these sections
> to be zero-sized at link time.
> Eliminates following ld warning:
>
> mips-alpine-linux-musl-ld: warning: orphan section `.rel.dyn'
> from `init/main.o' being placed in section `.rel.dyn'
>
> Adopted from x86/kernel/vmlinux.lds.S.
>
> Suggested-by: Fangrui Song <maskray@google.com>
> Signed-off-by: Alexander Lobakin <alobakin@pm.me>
Reviewed-by: Kees Cook <keescook@chromium.org>
--
Kees Cook
^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: [PATCH v4 mips-next 5/7] MIPS: vmlinux.lds.S: explicitly declare .got table
2021-01-07 13:20 ` [PATCH v4 mips-next 5/7] MIPS: vmlinux.lds.S: explicitly declare .got table Alexander Lobakin
@ 2021-01-07 21:49 ` Kees Cook
2021-01-08 21:17 ` Nathan Chancellor
1 sibling, 0 replies; 22+ messages in thread
From: Kees Cook @ 2021-01-07 21:49 UTC (permalink / raw)
To: Alexander Lobakin
Cc: Thomas Bogendoerfer, Arnd Bergmann, Nathan Chancellor,
Nick Desaulniers, Fangrui Song, Huacai Chen, Pei Huang,
Jiaxun Yang, Sami Tolvanen, Ingo Molnar, Ralf Baechle,
Corey Minyard, linux-mips, linux-kernel, linux-arch, stable,
clang-built-linux
On Thu, Jan 07, 2021 at 01:20:49PM +0000, Alexander Lobakin wrote:
> LLVM stack generates GOT table when building the kernel:
>
> ld.lld: warning: <internal>:(.got) is being placed in '.got'
>
> According to the debug assertions, it's not zero-sized and thus
> can't be handled the same way as .rel.dyn (like it's done for x86).
> Use the ARM/ARM64 path here and place it at the end of .text section.
>
> Reported-by: Nathan Chancellor <natechancellor@gmail.com>
> Signed-off-by: Alexander Lobakin <alobakin@pm.me>
Reviewed-by: Kees Cook <keescook@chromium.org>
--
Kees Cook
^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: [PATCH v4 mips-next 6/7] vmlinux.lds.h: catch compound literals into data and BSS
2021-01-07 13:20 ` [PATCH v4 mips-next 6/7] vmlinux.lds.h: catch compound literals into data and BSS Alexander Lobakin
@ 2021-01-07 21:51 ` Kees Cook
2021-01-08 21:19 ` Nathan Chancellor
1 sibling, 0 replies; 22+ messages in thread
From: Kees Cook @ 2021-01-07 21:51 UTC (permalink / raw)
To: Alexander Lobakin
Cc: Thomas Bogendoerfer, Arnd Bergmann, Nathan Chancellor,
Nick Desaulniers, Fangrui Song, Huacai Chen, Pei Huang,
Jiaxun Yang, Sami Tolvanen, Ingo Molnar, Ralf Baechle,
Corey Minyard, linux-mips, linux-kernel, linux-arch, stable,
clang-built-linux
On Thu, Jan 07, 2021 at 01:20:55PM +0000, Alexander Lobakin wrote:
> When building kernel with LD_DEAD_CODE_DATA_ELIMINATION, LLVM stack
> generates separate sections for compound literals, just like in case
> with enabled LTO [0]:
>
> ld.lld: warning: drivers/built-in.a(mtd/nand/spi/gigadevice.o):
> (.data..compoundliteral.14) is being placed in
> '.data..compoundliteral.14'
> ld.lld: warning: drivers/built-in.a(mtd/nand/spi/gigadevice.o):
> (.data..compoundliteral.15) is being placed in
> '.data..compoundliteral.15'
> ld.lld: warning: drivers/built-in.a(mtd/nand/spi/gigadevice.o):
> (.data..compoundliteral.16) is being placed in
> '.data..compoundliteral.16'
> ld.lld: warning: drivers/built-in.a(mtd/nand/spi/gigadevice.o):
> (.data..compoundliteral.17) is being placed in
> '.data..compoundliteral.17'
>
> [...]
>
> Handle this by adding the related sections to generic definitions
> as suggested by Sami [0].
>
> [0] https://lore.kernel.org/lkml/20201211184633.3213045-3-samitolvanen@google.com
>
> Suggested-by: Kees Cook <keescook@chromium.org>
> Signed-off-by: Alexander Lobakin <alobakin@pm.me>
Suggested-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
--
Kees Cook
^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: [PATCH v4 mips-next 0/7] MIPS: vmlinux.lds.S sections fixes & cleanup
2021-01-07 12:33 [PATCH v4 mips-next 0/7] MIPS: vmlinux.lds.S sections fixes & cleanup Alexander Lobakin
2021-01-07 12:34 ` [PATCH v4 mips-next 1/7] MIPS: vmlinux.lds.S: add missing PAGE_ALIGNED_DATA() section Alexander Lobakin
2021-01-07 13:20 ` [PATCH v4 mips-next 4/7] MIPS: vmlinux.lds.S: catch bad .rel.dyn at link time Alexander Lobakin
@ 2021-01-07 21:51 ` Kees Cook
2021-01-09 11:12 ` Thomas Bogendoerfer
3 siblings, 0 replies; 22+ messages in thread
From: Kees Cook @ 2021-01-07 21:51 UTC (permalink / raw)
To: Alexander Lobakin
Cc: Thomas Bogendoerfer, Arnd Bergmann, Nathan Chancellor,
Nick Desaulniers, Fangrui Song, Huacai Chen, Pei Huang,
Jiaxun Yang, Sami Tolvanen, Ingo Molnar, Ralf Baechle,
Corey Minyard, linux-mips, linux-kernel, linux-arch, stable,
clang-built-linux
On Thu, Jan 07, 2021 at 12:33:38PM +0000, Alexander Lobakin wrote:
> This series hunts the problems discovered after manual enabling of
> ARCH_WANT_LD_ORPHAN_WARN. Notably:
> - adds the missing PAGE_ALIGNED_DATA() section affecting VDSO
> placement (marked for stable);
> - properly stops .eh_frame section generation.
>
> Compile and runtime tested on MIPS32R2 CPS board with no issues
> using two different toolkits:
> - Binutils 2.35.1, GCC 10.2.0;
> - LLVM stack 11.0.0.
Nice! Thanks for hunting down the corner cases. :)
--
Kees Cook
^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: [PATCH v4 mips-next 1/7] MIPS: vmlinux.lds.S: add missing PAGE_ALIGNED_DATA() section
2021-01-07 12:34 ` [PATCH v4 mips-next 1/7] MIPS: vmlinux.lds.S: add missing PAGE_ALIGNED_DATA() section Alexander Lobakin
2021-01-07 12:34 ` [PATCH v4 mips-next 2/7] MIPS: vmlinux.lds.S: add ".gnu.attributes" to DISCARDS Alexander Lobakin
2021-01-07 12:35 ` [PATCH v4 mips-next 3/7] MIPS: properly stop .eh_frame generation Alexander Lobakin
@ 2021-01-08 21:10 ` Nathan Chancellor
2 siblings, 0 replies; 22+ messages in thread
From: Nathan Chancellor @ 2021-01-08 21:10 UTC (permalink / raw)
To: Alexander Lobakin
Cc: Thomas Bogendoerfer, Arnd Bergmann, Kees Cook, Nick Desaulniers,
Fangrui Song, Huacai Chen, Pei Huang, Jiaxun Yang, Sami Tolvanen,
Ingo Molnar, Ralf Baechle, Corey Minyard, linux-mips,
linux-kernel, linux-arch, stable, clang-built-linux
On Thu, Jan 07, 2021 at 12:34:47PM +0000, Alexander Lobakin wrote:
> MIPS uses its own declaration of rwdata, and thus it should be kept
> in sync with the asm-generic one. Currently PAGE_ALIGNED_DATA() is
> missing from the linker script, which emits the following ld
> warnings:
>
> mips-alpine-linux-musl-ld: warning: orphan section
> `.data..page_aligned' from `arch/mips/kernel/vdso.o' being placed
> in section `.data..page_aligned'
> mips-alpine-linux-musl-ld: warning: orphan section
> `.data..page_aligned' from `arch/mips/vdso/vdso-image.o' being placed
> in section `.data..page_aligned'
>
> Add the necessary declaration, so the mentioned structures will be
> placed in vmlinux as intended:
>
> ffffffff80630580 D __end_once
> ffffffff80630580 D __start___dyndbg
> ffffffff80630580 D __start_once
> ffffffff80630580 D __stop___dyndbg
> ffffffff80634000 d mips_vdso_data
> ffffffff80638000 d vdso_data
> ffffffff80638580 D _gp
> ffffffff8063c000 T __init_begin
> ffffffff8063c000 D _edata
> ffffffff8063c000 T _sinittext
>
> ->
>
> ffffffff805a4000 D __end_init_task
> ffffffff805a4000 D __nosave_begin
> ffffffff805a4000 D __nosave_end
> ffffffff805a4000 d mips_vdso_data
> ffffffff805a8000 d vdso_data
> ffffffff805ac000 D mmlist_lock
> ffffffff805ac080 D tasklist_lock
>
> Fixes: ebb5e78cc634 ("MIPS: Initial implementation of a VDSO")
> Cc: stable@vger.kernel.org # 4.4+
> Signed-off-by: Alexander Lobakin <alobakin@pm.me>
> Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
> ---
> arch/mips/kernel/vmlinux.lds.S | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/arch/mips/kernel/vmlinux.lds.S b/arch/mips/kernel/vmlinux.lds.S
> index 5e97e9d02f98..83e27a181206 100644
> --- a/arch/mips/kernel/vmlinux.lds.S
> +++ b/arch/mips/kernel/vmlinux.lds.S
> @@ -90,6 +90,7 @@ SECTIONS
>
> INIT_TASK_DATA(THREAD_SIZE)
> NOSAVE_DATA
> + PAGE_ALIGNED_DATA(PAGE_SIZE)
> CACHELINE_ALIGNED_DATA(1 << CONFIG_MIPS_L1_CACHE_SHIFT)
> READ_MOSTLY_DATA(1 << CONFIG_MIPS_L1_CACHE_SHIFT)
> DATA_DATA
> --
> 2.30.0
>
>
^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: [PATCH v4 mips-next 2/7] MIPS: vmlinux.lds.S: add ".gnu.attributes" to DISCARDS
2021-01-07 12:34 ` [PATCH v4 mips-next 2/7] MIPS: vmlinux.lds.S: add ".gnu.attributes" to DISCARDS Alexander Lobakin
@ 2021-01-08 21:12 ` Nathan Chancellor
0 siblings, 0 replies; 22+ messages in thread
From: Nathan Chancellor @ 2021-01-08 21:12 UTC (permalink / raw)
To: Alexander Lobakin
Cc: Thomas Bogendoerfer, Arnd Bergmann, Kees Cook, Nick Desaulniers,
Fangrui Song, Huacai Chen, Pei Huang, Jiaxun Yang, Sami Tolvanen,
Ingo Molnar, Ralf Baechle, Corey Minyard, linux-mips,
linux-kernel, linux-arch, stable, clang-built-linux
On Thu, Jan 07, 2021 at 12:34:53PM +0000, Alexander Lobakin wrote:
> Discard GNU attributes (MIPS FP type, GNU Hash etc.) at link time
> as kernel doesn't use it at all.
> Solves a dozen of the following ld warnings (one per every file):
>
> mips-alpine-linux-musl-ld: warning: orphan section `.gnu.attributes'
> from `arch/mips/kernel/head.o' being placed in section
> `.gnu.attributes'
> mips-alpine-linux-musl-ld: warning: orphan section `.gnu.attributes'
> from `init/main.o' being placed in section `.gnu.attributes'
>
> Signed-off-by: Alexander Lobakin <alobakin@pm.me>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
> ---
> arch/mips/kernel/vmlinux.lds.S | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/arch/mips/kernel/vmlinux.lds.S b/arch/mips/kernel/vmlinux.lds.S
> index 83e27a181206..16468957cba2 100644
> --- a/arch/mips/kernel/vmlinux.lds.S
> +++ b/arch/mips/kernel/vmlinux.lds.S
> @@ -221,6 +221,7 @@ SECTIONS
> /* ABI crap starts here */
> *(.MIPS.abiflags)
> *(.MIPS.options)
> + *(.gnu.attributes)
> *(.options)
> *(.pdr)
> *(.reginfo)
> --
> 2.30.0
>
>
^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: [PATCH v4 mips-next 3/7] MIPS: properly stop .eh_frame generation
2021-01-07 12:35 ` [PATCH v4 mips-next 3/7] MIPS: properly stop .eh_frame generation Alexander Lobakin
2021-01-07 21:48 ` Kees Cook
@ 2021-01-08 21:16 ` Nathan Chancellor
1 sibling, 0 replies; 22+ messages in thread
From: Nathan Chancellor @ 2021-01-08 21:16 UTC (permalink / raw)
To: Alexander Lobakin
Cc: Thomas Bogendoerfer, Arnd Bergmann, Kees Cook, Nick Desaulniers,
Fangrui Song, Huacai Chen, Pei Huang, Jiaxun Yang, Sami Tolvanen,
Ingo Molnar, Ralf Baechle, Corey Minyard, linux-mips,
linux-kernel, linux-arch, stable, clang-built-linux
On Thu, Jan 07, 2021 at 12:35:01PM +0000, Alexander Lobakin wrote:
> Commit 866b6a89c6d1 ("MIPS: Add DWARF unwinding to assembly") added
> -fno-asynchronous-unwind-tables to KBUILD_CFLAGS to prevent compiler
> from emitting .eh_frame symbols.
> However, as MIPS heavily uses CFI, that's not enough. Use the
> approach taken for x86 (as it also uses CFI) and explicitly put CFI
> symbols into the .debug_frame section (except for VDSO).
> This allows us to drop .eh_frame from DISCARDS as it's no longer
> being generated.
>
> Fixes: 866b6a89c6d1 ("MIPS: Add DWARF unwinding to assembly")
> Suggested-by: Kees Cook <keescook@chromium.org>
> Signed-off-by: Alexander Lobakin <alobakin@pm.me>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
> ---
> arch/mips/include/asm/asm.h | 18 ++++++++++++++++++
> arch/mips/kernel/vmlinux.lds.S | 1 -
> 2 files changed, 18 insertions(+), 1 deletion(-)
>
> diff --git a/arch/mips/include/asm/asm.h b/arch/mips/include/asm/asm.h
> index 3682d1a0bb80..908f6d6ae24b 100644
> --- a/arch/mips/include/asm/asm.h
> +++ b/arch/mips/include/asm/asm.h
> @@ -20,10 +20,27 @@
> #include <asm/sgidefs.h>
> #include <asm/asm-eva.h>
>
> +#ifndef __VDSO__
> +/*
> + * Emit CFI data in .debug_frame sections, not .eh_frame sections.
> + * We don't do DWARF unwinding at runtime, so only the offline DWARF
> + * information is useful to anyone. Note we should change this if we
> + * ever decide to enable DWARF unwinding at runtime.
> + */
> +#define CFI_SECTIONS .cfi_sections .debug_frame
> +#else
> + /*
> + * For the vDSO, emit both runtime unwind information and debug
> + * symbols for the .dbg file.
> + */
> +#define CFI_SECTIONS
> +#endif
> +
> /*
> * LEAF - declare leaf routine
> */
> #define LEAF(symbol) \
> + CFI_SECTIONS; \
> .globl symbol; \
> .align 2; \
> .type symbol, @function; \
> @@ -36,6 +53,7 @@ symbol: .frame sp, 0, ra; \
> * NESTED - declare nested routine entry point
> */
> #define NESTED(symbol, framesize, rpc) \
> + CFI_SECTIONS; \
> .globl symbol; \
> .align 2; \
> .type symbol, @function; \
> diff --git a/arch/mips/kernel/vmlinux.lds.S b/arch/mips/kernel/vmlinux.lds.S
> index 16468957cba2..0f4e46ea4458 100644
> --- a/arch/mips/kernel/vmlinux.lds.S
> +++ b/arch/mips/kernel/vmlinux.lds.S
> @@ -225,6 +225,5 @@ SECTIONS
> *(.options)
> *(.pdr)
> *(.reginfo)
> - *(.eh_frame)
> }
> }
> --
> 2.30.0
>
>
^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: [PATCH v4 mips-next 4/7] MIPS: vmlinux.lds.S: catch bad .rel.dyn at link time
2021-01-07 13:20 ` [PATCH v4 mips-next 4/7] MIPS: vmlinux.lds.S: catch bad .rel.dyn at link time Alexander Lobakin
` (3 preceding siblings ...)
2021-01-07 21:48 ` [PATCH v4 mips-next 4/7] MIPS: vmlinux.lds.S: catch bad .rel.dyn at link time Kees Cook
@ 2021-01-08 21:17 ` Nathan Chancellor
4 siblings, 0 replies; 22+ messages in thread
From: Nathan Chancellor @ 2021-01-08 21:17 UTC (permalink / raw)
To: Alexander Lobakin
Cc: Thomas Bogendoerfer, Arnd Bergmann, Kees Cook, Nick Desaulniers,
Fangrui Song, Huacai Chen, Pei Huang, Jiaxun Yang, Sami Tolvanen,
Ingo Molnar, Ralf Baechle, Corey Minyard, linux-mips,
linux-kernel, linux-arch, stable, clang-built-linux
On Thu, Jan 07, 2021 at 01:20:33PM +0000, Alexander Lobakin wrote:
> Catch any symbols placed in .rel.dyn and check for these sections
> to be zero-sized at link time.
> Eliminates following ld warning:
>
> mips-alpine-linux-musl-ld: warning: orphan section `.rel.dyn'
> from `init/main.o' being placed in section `.rel.dyn'
>
> Adopted from x86/kernel/vmlinux.lds.S.
>
> Suggested-by: Fangrui Song <maskray@google.com>
> Signed-off-by: Alexander Lobakin <alobakin@pm.me>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
> ---
> arch/mips/kernel/vmlinux.lds.S | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/arch/mips/kernel/vmlinux.lds.S b/arch/mips/kernel/vmlinux.lds.S
> index 0f4e46ea4458..0f736d60d43e 100644
> --- a/arch/mips/kernel/vmlinux.lds.S
> +++ b/arch/mips/kernel/vmlinux.lds.S
> @@ -226,4 +226,15 @@ SECTIONS
> *(.pdr)
> *(.reginfo)
> }
> +
> + /*
> + * Sections that should stay zero sized, which is safer to
> + * explicitly check instead of blindly discarding.
> + */
> +
> + .rel.dyn : {
> + *(.rel.*)
> + *(.rel_*)
> + }
> + ASSERT(SIZEOF(.rel.dyn) == 0, "Unexpected run-time relocations (.rel) detected!")
> }
> --
> 2.30.0
>
>
^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: [PATCH v4 mips-next 5/7] MIPS: vmlinux.lds.S: explicitly declare .got table
2021-01-07 13:20 ` [PATCH v4 mips-next 5/7] MIPS: vmlinux.lds.S: explicitly declare .got table Alexander Lobakin
2021-01-07 21:49 ` Kees Cook
@ 2021-01-08 21:17 ` Nathan Chancellor
1 sibling, 0 replies; 22+ messages in thread
From: Nathan Chancellor @ 2021-01-08 21:17 UTC (permalink / raw)
To: Alexander Lobakin
Cc: Thomas Bogendoerfer, Arnd Bergmann, Kees Cook, Nick Desaulniers,
Fangrui Song, Huacai Chen, Pei Huang, Jiaxun Yang, Sami Tolvanen,
Ingo Molnar, Ralf Baechle, Corey Minyard, linux-mips,
linux-kernel, linux-arch, stable, clang-built-linux
On Thu, Jan 07, 2021 at 01:20:49PM +0000, Alexander Lobakin wrote:
> LLVM stack generates GOT table when building the kernel:
>
> ld.lld: warning: <internal>:(.got) is being placed in '.got'
>
> According to the debug assertions, it's not zero-sized and thus
> can't be handled the same way as .rel.dyn (like it's done for x86).
> Use the ARM/ARM64 path here and place it at the end of .text section.
>
> Reported-by: Nathan Chancellor <natechancellor@gmail.com>
> Signed-off-by: Alexander Lobakin <alobakin@pm.me>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
> ---
> arch/mips/kernel/vmlinux.lds.S | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/arch/mips/kernel/vmlinux.lds.S b/arch/mips/kernel/vmlinux.lds.S
> index 0f736d60d43e..4709959f6985 100644
> --- a/arch/mips/kernel/vmlinux.lds.S
> +++ b/arch/mips/kernel/vmlinux.lds.S
> @@ -69,6 +69,7 @@ SECTIONS
> *(.text.*)
> *(.fixup)
> *(.gnu.warning)
> + *(.got)
> } :text = 0
> _etext = .; /* End of text section */
>
> --
> 2.30.0
>
>
^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: [PATCH v4 mips-next 6/7] vmlinux.lds.h: catch compound literals into data and BSS
2021-01-07 13:20 ` [PATCH v4 mips-next 6/7] vmlinux.lds.h: catch compound literals into data and BSS Alexander Lobakin
2021-01-07 21:51 ` Kees Cook
@ 2021-01-08 21:19 ` Nathan Chancellor
1 sibling, 0 replies; 22+ messages in thread
From: Nathan Chancellor @ 2021-01-08 21:19 UTC (permalink / raw)
To: Alexander Lobakin
Cc: Thomas Bogendoerfer, Arnd Bergmann, Kees Cook, Nick Desaulniers,
Fangrui Song, Huacai Chen, Pei Huang, Jiaxun Yang, Sami Tolvanen,
Ingo Molnar, Ralf Baechle, Corey Minyard, linux-mips,
linux-kernel, linux-arch, stable, clang-built-linux
On Thu, Jan 07, 2021 at 01:20:55PM +0000, Alexander Lobakin wrote:
> When building kernel with LD_DEAD_CODE_DATA_ELIMINATION, LLVM stack
> generates separate sections for compound literals, just like in case
> with enabled LTO [0]:
>
> ld.lld: warning: drivers/built-in.a(mtd/nand/spi/gigadevice.o):
> (.data..compoundliteral.14) is being placed in
> '.data..compoundliteral.14'
> ld.lld: warning: drivers/built-in.a(mtd/nand/spi/gigadevice.o):
> (.data..compoundliteral.15) is being placed in
> '.data..compoundliteral.15'
> ld.lld: warning: drivers/built-in.a(mtd/nand/spi/gigadevice.o):
> (.data..compoundliteral.16) is being placed in
> '.data..compoundliteral.16'
> ld.lld: warning: drivers/built-in.a(mtd/nand/spi/gigadevice.o):
> (.data..compoundliteral.17) is being placed in
> '.data..compoundliteral.17'
>
> [...]
>
> Handle this by adding the related sections to generic definitions
> as suggested by Sami [0].
>
> [0] https://lore.kernel.org/lkml/20201211184633.3213045-3-samitolvanen@google.com
>
> Suggested-by: Kees Cook <keescook@chromium.org>
> Signed-off-by: Alexander Lobakin <alobakin@pm.me>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
> ---
> include/asm-generic/vmlinux.lds.h | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
> index b2b3d81b1535..5f2f5b1db84f 100644
> --- a/include/asm-generic/vmlinux.lds.h
> +++ b/include/asm-generic/vmlinux.lds.h
> @@ -95,10 +95,10 @@
> */
> #ifdef CONFIG_LD_DEAD_CODE_DATA_ELIMINATION
> #define TEXT_MAIN .text .text.[0-9a-zA-Z_]*
> -#define DATA_MAIN .data .data.[0-9a-zA-Z_]* .data..LPBX*
> +#define DATA_MAIN .data .data.[0-9a-zA-Z_]* .data..L* .data..compoundliteral*
> #define SDATA_MAIN .sdata .sdata.[0-9a-zA-Z_]*
> -#define RODATA_MAIN .rodata .rodata.[0-9a-zA-Z_]*
> -#define BSS_MAIN .bss .bss.[0-9a-zA-Z_]*
> +#define RODATA_MAIN .rodata .rodata.[0-9a-zA-Z_]* .rodata..L*
> +#define BSS_MAIN .bss .bss.[0-9a-zA-Z_]* .bss..compoundliteral*
> #define SBSS_MAIN .sbss .sbss.[0-9a-zA-Z_]*
> #else
> #define TEXT_MAIN .text
> --
> 2.30.0
>
>
^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: [PATCH v4 mips-next 7/7] MIPS: select ARCH_WANT_LD_ORPHAN_WARN
2021-01-07 13:21 ` [PATCH v4 mips-next 7/7] MIPS: select ARCH_WANT_LD_ORPHAN_WARN Alexander Lobakin
@ 2021-01-08 21:19 ` Nathan Chancellor
0 siblings, 0 replies; 22+ messages in thread
From: Nathan Chancellor @ 2021-01-08 21:19 UTC (permalink / raw)
To: Alexander Lobakin
Cc: Thomas Bogendoerfer, Arnd Bergmann, Kees Cook, Nick Desaulniers,
Fangrui Song, Huacai Chen, Pei Huang, Jiaxun Yang, Sami Tolvanen,
Ingo Molnar, Ralf Baechle, Corey Minyard, linux-mips,
linux-kernel, linux-arch, stable, clang-built-linux
On Thu, Jan 07, 2021 at 01:21:02PM +0000, Alexander Lobakin wrote:
> Now, after that all the sections are explicitly described and
> declared in vmlinux.lds.S, we can enable ld orphan warnings to
> prevent from missing any new sections in future.
>
> Signed-off-by: Alexander Lobakin <alobakin@pm.me>
> Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
> ---
> arch/mips/Kconfig | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
> index d68df1febd25..d3e64cc0932b 100644
> --- a/arch/mips/Kconfig
> +++ b/arch/mips/Kconfig
> @@ -18,6 +18,7 @@ config MIPS
> select ARCH_USE_QUEUED_SPINLOCKS
> select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT if MMU
> select ARCH_WANT_IPC_PARSE_VERSION
> + select ARCH_WANT_LD_ORPHAN_WARN
> select BUILDTIME_TABLE_SORT
> select CLONE_BACKWARDS
> select CPU_NO_EFFICIENT_FFS if (TARGET_ISA_REV < 1)
> --
> 2.30.0
>
>
^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: [PATCH v4 mips-next 0/7] MIPS: vmlinux.lds.S sections fixes & cleanup
2021-01-07 12:33 [PATCH v4 mips-next 0/7] MIPS: vmlinux.lds.S sections fixes & cleanup Alexander Lobakin
` (2 preceding siblings ...)
2021-01-07 21:51 ` [PATCH v4 mips-next 0/7] MIPS: vmlinux.lds.S sections fixes & cleanup Kees Cook
@ 2021-01-09 11:12 ` Thomas Bogendoerfer
2021-01-09 17:22 ` Alexander Lobakin
3 siblings, 1 reply; 22+ messages in thread
From: Thomas Bogendoerfer @ 2021-01-09 11:12 UTC (permalink / raw)
To: Alexander Lobakin
Cc: Arnd Bergmann, Kees Cook, Nathan Chancellor, Nick Desaulniers,
Fangrui Song, Huacai Chen, Pei Huang, Jiaxun Yang, Sami Tolvanen,
Ingo Molnar, Ralf Baechle, Corey Minyard, linux-mips,
linux-kernel, linux-arch, stable, clang-built-linux
On Thu, Jan 07, 2021 at 12:33:38PM +0000, Alexander Lobakin wrote:
> This series hunts the problems discovered after manual enabling of
> ARCH_WANT_LD_ORPHAN_WARN. Notably:
> - adds the missing PAGE_ALIGNED_DATA() section affecting VDSO
> placement (marked for stable);
> - properly stops .eh_frame section generation.
>
> Compile and runtime tested on MIPS32R2 CPS board with no issues
> using two different toolkits:
> - Binutils 2.35.1, GCC 10.2.0;
> - LLVM stack 11.0.0.
>
> Since v3 [2]:
> - fix the third patch as GNU stack emits .rel.dyn into VDSO for
> some reason if .cfi_sections is specified.
>
> Since v2 [1]:
> - stop discarding .eh_frame and just prevent it from generating
> (Kees);
> - drop redundant sections assertions (Fangrui);
> - place GOT table in .text instead of asserting as it's not empty
> when building with LLVM (Nathan);
> - catch compound literals in generic definitions when building with
> LD_DEAD_CODE_DATA_ELIMINATION (Kees);
> - collect two Reviewed-bys (Kees).
>
> Since v1 [0]:
> - catch .got entries too as LLD may produce it (Nathan);
> - check for unwanted sections to be zero-sized instead of
> discarding (Fangrui).
>
> [0] https://lore.kernel.org/linux-mips/20210104121729.46981-1-alobakin@pm.me
> [1] https://lore.kernel.org/linux-mips/20210106200713.31840-1-alobakin@pm.me
> [2] https://lore.kernel.org/linux-mips/20210107115120.281008-1-alobakin@pm.me
>
> Alexander Lobakin (7):
> MIPS: vmlinux.lds.S: add missing PAGE_ALIGNED_DATA() section
> MIPS: vmlinux.lds.S: add ".gnu.attributes" to DISCARDS
> MIPS: properly stop .eh_frame generation
> MIPS: vmlinux.lds.S: catch bad .rel.dyn at link time
> MIPS: vmlinux.lds.S: explicitly declare .got table
> vmlinux.lds.h: catch compound literals into data and BSS
> MIPS: select ARCH_WANT_LD_ORPHAN_WARN
this breaks my builds:
LD vmlinux.o
MODPOST vmlinux.symvers
MODINFO modules.builtin.modinfo
GEN modules.builtin
LD .tmp_vmlinux.kallsyms1
mips64-linux-gnu-ld: Unexpected run-time relocations (.rel) detected!
$ mips64-linux-gnu-ld --version
GNU ld version 2.27-3.fc24
$ mips64-linux-gnu-gcc --version
mips64-linux-gnu-gcc (GCC) 6.1.1 20160621 (Red Hat Cross 6.1.1-2)
Thomas.
--
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea. [ RFC1925, 2.3 ]
^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: [PATCH v4 mips-next 0/7] MIPS: vmlinux.lds.S sections fixes & cleanup
2021-01-09 11:12 ` Thomas Bogendoerfer
@ 2021-01-09 17:22 ` Alexander Lobakin
0 siblings, 0 replies; 22+ messages in thread
From: Alexander Lobakin @ 2021-01-09 17:22 UTC (permalink / raw)
To: Thomas Bogendoerfer
Cc: Alexander Lobakin, Arnd Bergmann, Kees Cook, Nathan Chancellor,
Nick Desaulniers, Fangrui Song, Huacai Chen, Pei Huang,
Jiaxun Yang, Sami Tolvanen, Ingo Molnar, Ralf Baechle,
Corey Minyard, linux-mips, linux-kernel, linux-arch, stable,
clang-built-linux
From: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Date: Sat, 9 Jan 2021 12:12:59 +0100
> On Thu, Jan 07, 2021 at 12:33:38PM +0000, Alexander Lobakin wrote:
>> This series hunts the problems discovered after manual enabling of
>> ARCH_WANT_LD_ORPHAN_WARN. Notably:
>> - adds the missing PAGE_ALIGNED_DATA() section affecting VDSO
>> placement (marked for stable);
>> - properly stops .eh_frame section generation.
>>
>> Compile and runtime tested on MIPS32R2 CPS board with no issues
>> using two different toolkits:
>> - Binutils 2.35.1, GCC 10.2.0;
>> - LLVM stack 11.0.0.
>>
>> Since v3 [2]:
>> - fix the third patch as GNU stack emits .rel.dyn into VDSO for
>> some reason if .cfi_sections is specified.
>>
>> Since v2 [1]:
>> - stop discarding .eh_frame and just prevent it from generating
>> (Kees);
>> - drop redundant sections assertions (Fangrui);
>> - place GOT table in .text instead of asserting as it's not empty
>> when building with LLVM (Nathan);
>> - catch compound literals in generic definitions when building with
>> LD_DEAD_CODE_DATA_ELIMINATION (Kees);
>> - collect two Reviewed-bys (Kees).
>>
>> Since v1 [0]:
>> - catch .got entries too as LLD may produce it (Nathan);
>> - check for unwanted sections to be zero-sized instead of
>> discarding (Fangrui).
>>
>> [0] https://lore.kernel.org/linux-mips/20210104121729.46981-1-alobakin@pm.me
>> [1] https://lore.kernel.org/linux-mips/20210106200713.31840-1-alobakin@pm.me
>> [2] https://lore.kernel.org/linux-mips/20210107115120.281008-1-alobakin@pm.me
>>
>> Alexander Lobakin (7):
>> MIPS: vmlinux.lds.S: add missing PAGE_ALIGNED_DATA() section
>> MIPS: vmlinux.lds.S: add ".gnu.attributes" to DISCARDS
>> MIPS: properly stop .eh_frame generation
>> MIPS: vmlinux.lds.S: catch bad .rel.dyn at link time
>> MIPS: vmlinux.lds.S: explicitly declare .got table
>> vmlinux.lds.h: catch compound literals into data and BSS
>> MIPS: select ARCH_WANT_LD_ORPHAN_WARN
>
> this breaks my builds:
>
> LD vmlinux.o
> MODPOST vmlinux.symvers
> MODINFO modules.builtin.modinfo
> GEN modules.builtin
> LD .tmp_vmlinux.kallsyms1
> mips64-linux-gnu-ld: Unexpected run-time relocations (.rel) detected!
I think they should be handled as it's done for ARM64 [0]. Will do v5
soon.
[0] https://elixir.bootlin.com/linux/v5.11-rc2/source/arch/arm64/kernel/vmlinux.lds.S#L219
> $ mips64-linux-gnu-ld --version
> GNU ld version 2.27-3.fc24
>
> $ mips64-linux-gnu-gcc --version
> mips64-linux-gnu-gcc (GCC) 6.1.1 20160621 (Red Hat Cross 6.1.1-2)
>
> Thomas.
Thanks,
Alex
> --
> Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
> good idea. [ RFC1925, 2.3 ]
^ permalink raw reply [flat|nested] 22+ messages in thread
end of thread, other threads:[~2021-01-09 17:23 UTC | newest]
Thread overview: 22+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-01-07 12:33 [PATCH v4 mips-next 0/7] MIPS: vmlinux.lds.S sections fixes & cleanup Alexander Lobakin
2021-01-07 12:34 ` [PATCH v4 mips-next 1/7] MIPS: vmlinux.lds.S: add missing PAGE_ALIGNED_DATA() section Alexander Lobakin
2021-01-07 12:34 ` [PATCH v4 mips-next 2/7] MIPS: vmlinux.lds.S: add ".gnu.attributes" to DISCARDS Alexander Lobakin
2021-01-08 21:12 ` Nathan Chancellor
2021-01-07 12:35 ` [PATCH v4 mips-next 3/7] MIPS: properly stop .eh_frame generation Alexander Lobakin
2021-01-07 21:48 ` Kees Cook
2021-01-08 21:16 ` Nathan Chancellor
2021-01-08 21:10 ` [PATCH v4 mips-next 1/7] MIPS: vmlinux.lds.S: add missing PAGE_ALIGNED_DATA() section Nathan Chancellor
2021-01-07 13:20 ` [PATCH v4 mips-next 4/7] MIPS: vmlinux.lds.S: catch bad .rel.dyn at link time Alexander Lobakin
2021-01-07 13:20 ` [PATCH v4 mips-next 5/7] MIPS: vmlinux.lds.S: explicitly declare .got table Alexander Lobakin
2021-01-07 21:49 ` Kees Cook
2021-01-08 21:17 ` Nathan Chancellor
2021-01-07 13:20 ` [PATCH v4 mips-next 6/7] vmlinux.lds.h: catch compound literals into data and BSS Alexander Lobakin
2021-01-07 21:51 ` Kees Cook
2021-01-08 21:19 ` Nathan Chancellor
2021-01-07 13:21 ` [PATCH v4 mips-next 7/7] MIPS: select ARCH_WANT_LD_ORPHAN_WARN Alexander Lobakin
2021-01-08 21:19 ` Nathan Chancellor
2021-01-07 21:48 ` [PATCH v4 mips-next 4/7] MIPS: vmlinux.lds.S: catch bad .rel.dyn at link time Kees Cook
2021-01-08 21:17 ` Nathan Chancellor
2021-01-07 21:51 ` [PATCH v4 mips-next 0/7] MIPS: vmlinux.lds.S sections fixes & cleanup Kees Cook
2021-01-09 11:12 ` Thomas Bogendoerfer
2021-01-09 17:22 ` Alexander Lobakin
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.