jump label: fix passing kbuild_cflags when checking for asm goto support

PATCH Superseded Gleb Fotengauer-Malinovskiy 4 participants 10 messages Mar 10, 2017 – Mar 21, 2017 Kbuild

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Gleb Fotengauer-Malinovskiy

author

2017-03-10 16:25 UTC #0 lore raw

PATCH 1/1 jump label: fix passing kbuild_cflags when checking for asm goto support

The latest change of asm goto support check added passing of KBUILD_CFLAGS to compiler. When these flags reference gcc plugins, there is a race condition between the build of these plugins and their use in this asm goto support check.

This change moves the check before all these references are added to KBUILD_CFLAGS. This is correct because subsequent KBUILD_CFLAGS modifications are not relevant to this check.

Reported-by Anton V. Boyarshinov <[email protected]>

Fixes 35f860f9ba6a ("jump label: pass kbuild_cflags when checking for asm goto support")

Cc [email protected] # v4.10

Signed-off-by Gleb Fotengauer-Malinovskiy <[email protected]>

Signed-off-by Dmitry V. Levin <[email protected]>

---
 Makefile | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

Makefile +6 -6

index 165cf97..7e3aade 100644
@@ -653,6 +653,12 @@ KBUILD_CFLAGS += $(call cc-ifversion, -lt, 0409, \
 # Tell gcc to never replace conditional load with a non-conditional one
 KBUILD_CFLAGS	+= $(call cc-option,--param=allow-store-data-races=0)
 
+# check for 'asm goto'
+ifeq ($(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-goto.sh $(CC) $(KBUILD_CFLAGS)), y)
+	KBUILD_CFLAGS += -DCC_HAVE_ASM_GOTO
+	KBUILD_AFLAGS += -DCC_HAVE_ASM_GOTO
+endif
+
 include scripts/Makefile.gcc-plugins
 
 ifdef CONFIG_READABLE_ASM

@@ -798,12 +804,6 @@ KBUILD_CFLAGS   += $(call cc-option,-Werror=incompatible-pointer-types)
 # use the deterministic mode of AR if available
 KBUILD_ARFLAGS := $(call ar-option,D)
 
-# check for 'asm goto'
-ifeq ($(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-goto.sh $(CC) $(KBUILD_CFLAGS)), y)
-	KBUILD_CFLAGS += -DCC_HAVE_ASM_GOTO
-	KBUILD_AFLAGS += -DCC_HAVE_ASM_GOTO
-endif
-
 include scripts/Makefile.kasan
 include scripts/Makefile.extrawarn
 include scripts/Makefile.ubsan

Signature · 1 line

glebfm

Steven Rostedt

2017-03-10 17:04 UTC #1 lore raw

Quoted 8 lines · On Fri, 10 Mar 2017 19:24:18 +0300 Gleb Fotengauer-Malinovskiy…

The latest change of asm goto support check added passing of KBUILD_CFLAGS to compiler. When these flags reference gcc plugins, there is a race condition between the build of these plugins and their use in this asm goto support check.
This change moves the check before all these references are added to KBUILD_CFLAGS. This is correct because subsequent KBUILD_CFLAGS modifications are not relevant to this check.

What exactly breaks when the race happens?

-- Steve

Quoted 41 lines

Reported-by Anton V. Boyarshinov <[email protected]>

Fixes 35f860f9ba6a ("jump label: pass kbuild_cflags when checking for asm goto support")

Cc [email protected] # v4.10

Signed-off-by Gleb Fotengauer-Malinovskiy <[email protected]>

Signed-off-by Dmitry V. Levin <[email protected]>

---
 Makefile | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

Makefile +6 -6

index 165cf97..7e3aade 100644
@@ -653,6 +653,12 @@ KBUILD_CFLAGS += $(call cc-ifversion, -lt, 0409, \
 # Tell gcc to never replace conditional load with a non-conditional one
 KBUILD_CFLAGS	+= $(call cc-option,--param=allow-store-data-races=0)
 
+# check for 'asm goto'
+ifeq ($(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-goto.sh $(CC) $(KBUILD_CFLAGS)), y)
+	KBUILD_CFLAGS += -DCC_HAVE_ASM_GOTO
+	KBUILD_AFLAGS += -DCC_HAVE_ASM_GOTO
+endif
+
 include scripts/Makefile.gcc-plugins
 
 ifdef CONFIG_READABLE_ASM

@@ -798,12 +804,6 @@ KBUILD_CFLAGS   += $(call cc-option,-Werror=incompatible-pointer-types)
 # use the deterministic mode of AR if available
 KBUILD_ARFLAGS := $(call ar-option,D)
 
-# check for 'asm goto'
-ifeq ($(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-goto.sh $(CC) $(KBUILD_CFLAGS)), y)
-	KBUILD_CFLAGS += -DCC_HAVE_ASM_GOTO
-	KBUILD_AFLAGS += -DCC_HAVE_ASM_GOTO
-endif
-
 include scripts/Makefile.kasan
 include scripts/Makefile.extrawarn
 include scripts/Makefile.ubsan

Gleb Fotengauer-Malinovskiy

author

2017-03-10 17:41 UTC #2 lore raw

Quoted 8 lines · Steven Rostedt

Quoted 5 lines · On Fri, 10 Mar 2017 19:24:18 +0300 Gleb Fotengauer-Malinovskiy…
The latest change of asm goto support check added passing of KBUILD_CFLAGS to compiler. When these flags reference gcc plugins, there is a race condition between the build of these plugins and their use in this asm goto support check.

Quoted 5 lines

Quoted 3 lines
This change moves the check before all these references are added to KBUILD_CFLAGS. This is correct because subsequent KBUILD_CFLAGS modifications are not relevant to this check.
What exactly breaks when the race happens?

Actually, this is not quite a race. When you run "make bzImage" followed by "make modules", the kernel is always built with HAVE_JUMP_LABEL disabled, while the modules are built depending on CONFIG_JUMP_LABEL. If HAVE_JUMP_LABEL macro happens to be different, modules are built with undefined references:

ERROR: "static_key_slow_inc" [net/netfilter/xt_TEE.ko] undefined!
ERROR: "static_key_slow_dec" [net/netfilter/xt_TEE.ko] undefined!
ERROR: "static_key_slow_dec" [net/netfilter/nft_meta.ko] undefined!
ERROR: "static_key_slow_inc" [net/netfilter/nft_meta.ko] undefined!
ERROR: "nf_hooks_needed" [net/netfilter/ipvs/ip_vs.ko] undefined!
ERROR: "nf_hooks_needed" [net/ipv6/ipv6.ko] undefined!
ERROR: "static_key_count" [net/ipv6/ipv6.ko] undefined!
ERROR: "static_key_slow_inc" [net/ipv6/ipv6.ko] undefined!
ERROR: "nf_hooks_needed" [net/decnet/decnet.ko] undefined!

Signature · 1 line

glebfm

Steven Rostedt

2017-03-10 17:42 UTC #3 lore raw

Quoted 21 lines · On Fri, 10 Mar 2017 20:39:52 +0300 Gleb Fotengauer-Malinovskiy…

Quoted 8 lines · Steven Rostedt
Quoted 5 lines · On Fri, 10 Mar 2017 19:24:18 +0300 Gleb Fotengauer-Malinovskiy…
The latest change of asm goto support check added passing of KBUILD_CFLAGS to compiler. When these flags reference gcc plugins, there is a race condition between the build of these plugins and their use in this asm goto support check.
Quoted 5 lines
Quoted 3 lines
This change moves the check before all these references are added to KBUILD_CFLAGS. This is correct because subsequent KBUILD_CFLAGS modifications are not relevant to this check.
What exactly breaks when the race happens?
Actually, this is not quite a race. When you run "make bzImage" followed by "make modules", the kernel is always built with HAVE_JUMP_LABEL disabled, while the modules are built depending on CONFIG_JUMP_LABEL. If HAVE_JUMP_LABEL macro happens to be different, modules are built with undefined references:

Quoted 10 lines

ERROR: "static_key_slow_inc" [net/netfilter/xt_TEE.ko] undefined!
ERROR: "static_key_slow_dec" [net/netfilter/xt_TEE.ko] undefined!
ERROR: "static_key_slow_dec" [net/netfilter/nft_meta.ko] undefined!
ERROR: "static_key_slow_inc" [net/netfilter/nft_meta.ko] undefined!
ERROR: "nf_hooks_needed" [net/netfilter/ipvs/ip_vs.ko] undefined!
ERROR: "nf_hooks_needed" [net/ipv6/ipv6.ko] undefined!
ERROR: "static_key_count" [net/ipv6/ipv6.ko] undefined!
ERROR: "static_key_slow_inc" [net/ipv6/ipv6.ko] undefined!
ERROR: "nf_hooks_needed" [net/decnet/decnet.ko] undefined!

Can you add the above info in the change log and repost?

Thanks,

-- Steve

Gleb Fotengauer-Malinovskiy

author

2017-03-10 17:56 UTC #4 lore raw

PATCH v2 1/1 jump label: fix passing kbuild_cflags when checking for asm goto support

The latest change of asm goto support check added passing of KBUILD_CFLAGS to compiler. When these flags reference gcc plugins that are not built yet, the check fails.

When one runs "make bzImage" followed by "make modules", the kernel is always built with HAVE_JUMP_LABEL disabled, while the modules are built depending on CONFIG_JUMP_LABEL. If HAVE_JUMP_LABEL macro happens to be different, modules are built with undefined references, e.g.:

This change moves the check before all these references are added to KBUILD_CFLAGS. This is correct because subsequent KBUILD_CFLAGS modifications are not relevant to this check.

Reported-by Anton V. Boyarshinov <[email protected]>

Fixes 35f860f9ba6a ("jump label: pass kbuild_cflags when checking for asm goto support")

Cc [email protected] # v4.10

Signed-off-by Gleb Fotengauer-Malinovskiy <[email protected]>

Signed-off-by Dmitry V. Levin <[email protected]>

---
v2: update description of the problem fixed by this patch

 Makefile | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

Makefile +6 -6

index 165cf97..7e3aade 100644
@@ -653,6 +653,12 @@ KBUILD_CFLAGS += $(call cc-ifversion, -lt, 0409, \
 # Tell gcc to never replace conditional load with a non-conditional one
 KBUILD_CFLAGS	+= $(call cc-option,--param=allow-store-data-races=0)
 
+# check for 'asm goto'
+ifeq ($(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-goto.sh $(CC) $(KBUILD_CFLAGS)), y)
+	KBUILD_CFLAGS += -DCC_HAVE_ASM_GOTO
+	KBUILD_AFLAGS += -DCC_HAVE_ASM_GOTO
+endif
+
 include scripts/Makefile.gcc-plugins
 
 ifdef CONFIG_READABLE_ASM

@@ -798,12 +804,6 @@ KBUILD_CFLAGS   += $(call cc-option,-Werror=incompatible-pointer-types)
 # use the deterministic mode of AR if available
 KBUILD_ARFLAGS := $(call ar-option,D)
 
-# check for 'asm goto'
-ifeq ($(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-goto.sh $(CC) $(KBUILD_CFLAGS)), y)
-	KBUILD_CFLAGS += -DCC_HAVE_ASM_GOTO
-	KBUILD_AFLAGS += -DCC_HAVE_ASM_GOTO
-endif
-
 include scripts/Makefile.kasan
 include scripts/Makefile.extrawarn
 include scripts/Makefile.ubsan

Signature · 1 line

glebfm

Steven Rostedt

Acked-by on v2 1/1

2017-03-10 18:05 UTC #5 lore raw

Acked-by Steven Rostedt (VMware) <[email protected]>

Andrew, want to take this through your tree?

Thanks,

-- Steve

Quoted 63 lines · On Fri, 10 Mar 2017 20:55:36 +0300 Gleb Fotengauer-Malinovskiy…

The latest change of asm goto support check added passing of KBUILD_CFLAGS to compiler. When these flags reference gcc plugins that are not built yet, the check fails.
When one runs "make bzImage" followed by "make modules", the kernel is always built with HAVE_JUMP_LABEL disabled, while the modules are built depending on CONFIG_JUMP_LABEL. If HAVE_JUMP_LABEL macro happens to be different, modules are built with undefined references, e.g.:
ERROR: "static_key_slow_inc" [net/netfilter/xt_TEE.ko] undefined!
ERROR: "static_key_slow_dec" [net/netfilter/xt_TEE.ko] undefined!
ERROR: "static_key_slow_dec" [net/netfilter/nft_meta.ko] undefined!
ERROR: "static_key_slow_inc" [net/netfilter/nft_meta.ko] undefined!
ERROR: "nf_hooks_needed" [net/netfilter/ipvs/ip_vs.ko] undefined!
ERROR: "nf_hooks_needed" [net/ipv6/ipv6.ko] undefined!
ERROR: "static_key_count" [net/ipv6/ipv6.ko] undefined!
ERROR: "static_key_slow_inc" [net/ipv6/ipv6.ko] undefined!
This change moves the check before all these references are added to KBUILD_CFLAGS. This is correct because subsequent KBUILD_CFLAGS modifications are not relevant to this check.
Reported-by Anton V. Boyarshinov <[email protected]>
Fixes 35f860f9ba6a ("jump label: pass kbuild_cflags when checking for asm goto support")
Cc [email protected] # v4.10
Signed-off-by Gleb Fotengauer-Malinovskiy <[email protected]>
Signed-off-by Dmitry V. Levin <[email protected]>
---
v2: update description of the problem fixed by this patch
 Makefile | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)
Makefile +6 -6
index 165cf97..7e3aade 100644
@@ -653,6 +653,12 @@ KBUILD_CFLAGS += $(call cc-ifversion, -lt, 0409, \
 # Tell gcc to never replace conditional load with a non-conditional one
 KBUILD_CFLAGS	+= $(call cc-option,--param=allow-store-data-races=0)
 
+# check for 'asm goto'
+ifeq ($(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-goto.sh $(CC) $(KBUILD_CFLAGS)), y)
+	KBUILD_CFLAGS += -DCC_HAVE_ASM_GOTO
+	KBUILD_AFLAGS += -DCC_HAVE_ASM_GOTO
+endif
+
 include scripts/Makefile.gcc-plugins
 
 ifdef CONFIG_READABLE_ASM
@@ -798,12 +804,6 @@ KBUILD_CFLAGS   += $(call cc-option,-Werror=incompatible-pointer-types)
 # use the deterministic mode of AR if available
 KBUILD_ARFLAGS := $(call ar-option,D)
 
-# check for 'asm goto'
-ifeq ($(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-goto.sh $(CC) $(KBUILD_CFLAGS)), y)
-	KBUILD_CFLAGS += -DCC_HAVE_ASM_GOTO
-	KBUILD_AFLAGS += -DCC_HAVE_ASM_GOTO
-endif
-
 include scripts/Makefile.kasan
 include scripts/Makefile.extrawarn
 include scripts/Makefile.ubsan

David Lin

Acked-by on v2 1/1

2017-03-10 18:30 UTC #6 lore raw

In reply to Gleb Fotengauer-Malinovskiy

Quoted 23 lines · Gleb Fotengauer-Malinovskiy

The latest change of asm goto support check added passing of KBUILD_CFLAGS to compiler. When these flags reference gcc plugins that are not built yet, the check fails.
When one runs "make bzImage" followed by "make modules", the kernel is always built with HAVE_JUMP_LABEL disabled, while the modules are built depending on CONFIG_JUMP_LABEL. If HAVE_JUMP_LABEL macro happens to be different, modules are built with undefined references, e.g.:
ERROR: "static_key_slow_inc" [net/netfilter/xt_TEE.ko] undefined!
ERROR: "static_key_slow_dec" [net/netfilter/xt_TEE.ko] undefined!
ERROR: "static_key_slow_dec" [net/netfilter/nft_meta.ko] undefined!
ERROR: "static_key_slow_inc" [net/netfilter/nft_meta.ko] undefined!
ERROR: "nf_hooks_needed" [net/netfilter/ipvs/ip_vs.ko] undefined!
ERROR: "nf_hooks_needed" [net/ipv6/ipv6.ko] undefined!
ERROR: "static_key_count" [net/ipv6/ipv6.ko] undefined!
ERROR: "static_key_slow_inc" [net/ipv6/ipv6.ko] undefined!
This change moves the check before all these references are added to KBUILD_CFLAGS. This is correct because subsequent KBUILD_CFLAGS modifications are not relevant to this check.

Quoted 6 lines

Reported-by Anton V. Boyarshinov <[email protected]>
Fixes 35f860f9ba6a ("jump label: pass kbuild_cflags when checking for asm goto support")
Cc [email protected] # v4.10
Signed-off-by Gleb Fotengauer-Malinovskiy <[email protected]>
Signed-off-by Dmitry V. Levin <[email protected]>
---

Acked-by David Lin <[email protected]>

Gleb Fotengauer-Malinovskiy

author

2017-03-20 17:17 UTC #7 lore raw

PATCH v2 1/1 jump label: fix passing kbuild_cflags when checking for asm goto support

In reply to Gleb Fotengauer-Malinovskiy

The latest change of asm goto support check added passing of KBUILD_CFLAGS to compiler. When these flags reference gcc plugins that are not built yet, the check fails.

This change moves the check before all these references are added to KBUILD_CFLAGS. This is correct because subsequent KBUILD_CFLAGS modifications are not relevant to this check.

Reported-by Anton V. Boyarshinov <[email protected]>

Fixes 35f860f9ba6a ("jump label: pass kbuild_cflags when checking for asm goto support")

Cc [email protected] # v4.10

Signed-off-by Gleb Fotengauer-Malinovskiy <[email protected]>

Signed-off-by Dmitry V. Levin <[email protected]>

Acked-by Steven Rostedt (VMware) <[email protected]>

Acked-by David Lin <[email protected]>

---
v2: update description of the problem fixed by this patch

 Makefile | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

Makefile +6 -6

index 165cf97..7e3aade 100644
@@ -653,6 +653,12 @@ KBUILD_CFLAGS += $(call cc-ifversion, -lt, 0409, \
 # Tell gcc to never replace conditional load with a non-conditional one
 KBUILD_CFLAGS	+= $(call cc-option,--param=allow-store-data-races=0)
 
+# check for 'asm goto'
+ifeq ($(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-goto.sh $(CC) $(KBUILD_CFLAGS)), y)
+	KBUILD_CFLAGS += -DCC_HAVE_ASM_GOTO
+	KBUILD_AFLAGS += -DCC_HAVE_ASM_GOTO
+endif
+
 include scripts/Makefile.gcc-plugins
 
 ifdef CONFIG_READABLE_ASM

@@ -798,12 +804,6 @@ KBUILD_CFLAGS   += $(call cc-option,-Werror=incompatible-pointer-types)
 # use the deterministic mode of AR if available
 KBUILD_ARFLAGS := $(call ar-option,D)
 
-# check for 'asm goto'
-ifeq ($(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-goto.sh $(CC) $(KBUILD_CFLAGS)), y)
-	KBUILD_CFLAGS += -DCC_HAVE_ASM_GOTO
-	KBUILD_AFLAGS += -DCC_HAVE_ASM_GOTO
-endif
-
 include scripts/Makefile.kasan
 include scripts/Makefile.extrawarn
 include scripts/Makefile.ubsan

Signature · 1 line

glebfm

Masahiro Yamada

2017-03-21 17:49 UTC #8 lore raw

2017-03-21 2:15 GMT+09:00 Gleb Fotengauer-Malinovskiy <[email protected]>:

Quoted 29 lines

The latest change of asm goto support check added passing of KBUILD_CFLAGS to compiler. When these flags reference gcc plugins that are not built yet, the check fails.
When one runs "make bzImage" followed by "make modules", the kernel is always built with HAVE_JUMP_LABEL disabled, while the modules are built depending on CONFIG_JUMP_LABEL. If HAVE_JUMP_LABEL macro happens to be different, modules are built with undefined references, e.g.:
ERROR: "static_key_slow_inc" [net/netfilter/xt_TEE.ko] undefined!
ERROR: "static_key_slow_dec" [net/netfilter/xt_TEE.ko] undefined!
ERROR: "static_key_slow_dec" [net/netfilter/nft_meta.ko] undefined!
ERROR: "static_key_slow_inc" [net/netfilter/nft_meta.ko] undefined!
ERROR: "nf_hooks_needed" [net/netfilter/ipvs/ip_vs.ko] undefined!
ERROR: "nf_hooks_needed" [net/ipv6/ipv6.ko] undefined!
ERROR: "static_key_count" [net/ipv6/ipv6.ko] undefined!
ERROR: "static_key_slow_inc" [net/ipv6/ipv6.ko] undefined!
This change moves the check before all these references are added to KBUILD_CFLAGS. This is correct because subsequent KBUILD_CFLAGS modifications are not relevant to this check.
Reported-by Anton V. Boyarshinov <[email protected]>
Fixes 35f860f9ba6a ("jump label: pass kbuild_cflags when checking for asm goto support")
Cc [email protected] # v4.10
Signed-off-by Gleb Fotengauer-Malinovskiy <[email protected]>
Signed-off-by Dmitry V. Levin <[email protected]>
Acked-by Steven Rostedt (VMware) <[email protected]>
Acked-by David Lin <[email protected]>

Quoted 3 lines

---
v2: update description of the problem fixed by this patch

I assume this PING is addressed to me.

First, Steven asked Andrew to pick up this,
but I have not seen it in linux-next yet. So,

Applied to linux-kbuild/fixes. Thanks!

Signature · 2 lines

Best Regards
Masahiro Yamada

Steven Rostedt

2017-03-21 18:05 UTC #9 lore raw

Quoted 7 lines · On Wed, 22 Mar 2017 02:48:44 +0900 Masahiro Yamada…

I assume this PING is addressed to me.
First, Steven asked Andrew to pick up this,
but I have not seen it in linux-next yet. So,
Applied to linux-kbuild/fixes. Thanks!

Thanks Masahiro!

-- Steve