From: Masahiro Yamada <masahiroy@kernel.org>
Date: Wed, 23 Dec 2020 17:11:41 +0000 (+0900)
Subject: powerpc/vdso: fix unnecessary rebuilds of vgettimeofday.o
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=bce74491c300;p=linux.git
powerpc/vdso: fix unnecessary rebuilds of vgettimeofday.o
vgettimeofday.o is unnecessarily rebuilt. Adding it to 'targets' is not
enough to fix the issue. Kbuild is correctly rebuilding it because the
command line is changed.
PowerPC builds each vdso directory twice; first in vdso_prepare to
generate vdso{32,64}-offsets.h, second as part of the ordinary build
process to embed vdso{32,64}.so.dbg into the kernel.
The problem shows up when CONFIG_PPC_WERROR=y due to the following line
in arch/powerpc/Kbuild:
subdir-ccflags-$(CONFIG_PPC_WERROR) := -Werror
In the preparation stage, Kbuild directly visits the vdso directories,
hence it does not inherit subdir-ccflags-y. In the second descend,
Kbuild adds -Werror, which results in the command line flipping
with/without -Werror.
It implies a potential danger; if a more critical flag that would impact
the resulted vdso, the offsets recorded in the headers might be different
from real offsets in the embedded vdso images.
Removing the unneeded second descend solves the problem.
Reported-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/linuxppc-dev/87tuslxhry.fsf@mpe.ellerman.id.au/
Link: https://lore.kernel.org/r/20201223171142.707053-1-masahiroy@kernel.org
---
diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
index fe2ef598e2ead..79ee7750937db 100644
--- a/arch/powerpc/kernel/Makefile
+++ b/arch/powerpc/kernel/Makefile
@@ -51,7 +51,7 @@ obj-y += ptrace/
obj-$(CONFIG_PPC64) += setup_64.o \
paca.o nvram_64.o note.o syscall_64.o
obj-$(CONFIG_COMPAT) += sys_ppc32.o signal_32.o
-obj-$(CONFIG_VDSO32) += vdso32/
+obj-$(CONFIG_VDSO32) += vdso32_wrapper.o
obj-$(CONFIG_PPC_WATCHDOG) += watchdog.o
obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o
obj-$(CONFIG_PPC_DAWR) += dawr.o
@@ -60,7 +60,7 @@ obj-$(CONFIG_PPC_BOOK3S_64) += cpu_setup_power.o
obj-$(CONFIG_PPC_BOOK3S_64) += mce.o mce_power.o
obj-$(CONFIG_PPC_BOOK3E_64) += exceptions-64e.o idle_book3e.o
obj-$(CONFIG_PPC_BARRIER_NOSPEC) += security.o
-obj-$(CONFIG_PPC64) += vdso64/
+obj-$(CONFIG_PPC64) += vdso64_wrapper.o
obj-$(CONFIG_ALTIVEC) += vecemu.o
obj-$(CONFIG_PPC_BOOK3S_IDLE) += idle_book3s.o
procfs-y := proc_powerpc.o
diff --git a/arch/powerpc/kernel/vdso32/Makefile b/arch/powerpc/kernel/vdso32/Makefile
index 9cb6f524854b9..7d9a6fee0e3dc 100644
--- a/arch/powerpc/kernel/vdso32/Makefile
+++ b/arch/powerpc/kernel/vdso32/Makefile
@@ -30,7 +30,7 @@ CC32FLAGS += -m32
KBUILD_CFLAGS := $(filter-out -mcmodel=medium -mabi=elfv1 -mabi=elfv2 -mcall-aixdesc,$(KBUILD_CFLAGS))
endif
-targets := $(obj-vdso32) vdso32.so.dbg
+targets := $(obj-vdso32) vdso32.so.dbg vgettimeofday.o
obj-vdso32 := $(addprefix $(obj)/, $(obj-vdso32))
GCOV_PROFILE := n
@@ -46,9 +46,6 @@ obj-y += vdso32_wrapper.o
targets += vdso32.lds
CPPFLAGS_vdso32.lds += -P -C -Upowerpc
-# Force dependency (incbin is bad)
-$(obj)/vdso32_wrapper.o : $(obj)/vdso32.so.dbg
-
# link rule for the .so file, .lds has to be first
$(obj)/vdso32.so.dbg: $(src)/vdso32.lds $(obj-vdso32) $(obj)/vgettimeofday.o FORCE
$(call if_changed,vdso32ld_and_check)
diff --git a/arch/powerpc/kernel/vdso32/vdso32_wrapper.S b/arch/powerpc/kernel/vdso32/vdso32_wrapper.S
deleted file mode 100644
index 3f5ef035b0a98..0000000000000
--- a/arch/powerpc/kernel/vdso32/vdso32_wrapper.S
+++ /dev/null
@@ -1,14 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-#include <linux/linkage.h>
-#include <asm/page.h>
-
- __PAGE_ALIGNED_DATA
-
- .globl vdso32_start, vdso32_end
- .balign PAGE_SIZE
-vdso32_start:
- .incbin "arch/powerpc/kernel/vdso32/vdso32.so.dbg"
- .balign PAGE_SIZE
-vdso32_end:
-
- .previous
diff --git a/arch/powerpc/kernel/vdso32_wrapper.S b/arch/powerpc/kernel/vdso32_wrapper.S
new file mode 100644
index 0000000000000..3f5ef035b0a98
--- /dev/null
+++ b/arch/powerpc/kernel/vdso32_wrapper.S
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#include <linux/linkage.h>
+#include <asm/page.h>
+
+ __PAGE_ALIGNED_DATA
+
+ .globl vdso32_start, vdso32_end
+ .balign PAGE_SIZE
+vdso32_start:
+ .incbin "arch/powerpc/kernel/vdso32/vdso32.so.dbg"
+ .balign PAGE_SIZE
+vdso32_end:
+
+ .previous
diff --git a/arch/powerpc/kernel/vdso64/Makefile b/arch/powerpc/kernel/vdso64/Makefile
index bf363ff371521..a06fb9b461fc7 100644
--- a/arch/powerpc/kernel/vdso64/Makefile
+++ b/arch/powerpc/kernel/vdso64/Makefile
@@ -17,7 +17,7 @@ endif
# Build rules
-targets := $(obj-vdso64) vdso64.so.dbg
+targets := $(obj-vdso64) vdso64.so.dbg vgettimeofday.o
obj-vdso64 := $(addprefix $(obj)/, $(obj-vdso64))
GCOV_PROFILE := n
@@ -29,15 +29,11 @@ ccflags-y := -shared -fno-common -fno-builtin -nostdlib \
-Wl,-soname=linux-vdso64.so.1 -Wl,--hash-style=both
asflags-y := -D__VDSO64__ -s
-obj-y += vdso64_wrapper.o
targets += vdso64.lds
CPPFLAGS_vdso64.lds += -P -C -U$(ARCH)
$(obj)/vgettimeofday.o: %.o: %.c FORCE
-# Force dependency (incbin is bad)
-$(obj)/vdso64_wrapper.o : $(obj)/vdso64.so.dbg
-
# link rule for the .so file, .lds has to be first
$(obj)/vdso64.so.dbg: $(src)/vdso64.lds $(obj-vdso64) $(obj)/vgettimeofday.o FORCE
$(call if_changed,vdso64ld_and_check)
diff --git a/arch/powerpc/kernel/vdso64/vdso64_wrapper.S b/arch/powerpc/kernel/vdso64/vdso64_wrapper.S
deleted file mode 100644
index 1d56d81fe3b39..0000000000000
--- a/arch/powerpc/kernel/vdso64/vdso64_wrapper.S
+++ /dev/null
@@ -1,14 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-#include <linux/linkage.h>
-#include <asm/page.h>
-
- __PAGE_ALIGNED_DATA
-
- .globl vdso64_start, vdso64_end
- .balign PAGE_SIZE
-vdso64_start:
- .incbin "arch/powerpc/kernel/vdso64/vdso64.so.dbg"
- .balign PAGE_SIZE
-vdso64_end:
-
- .previous
diff --git a/arch/powerpc/kernel/vdso64_wrapper.S b/arch/powerpc/kernel/vdso64_wrapper.S
new file mode 100644
index 0000000000000..1d56d81fe3b39
--- /dev/null
+++ b/arch/powerpc/kernel/vdso64_wrapper.S
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#include <linux/linkage.h>
+#include <asm/page.h>
+
+ __PAGE_ALIGNED_DATA
+
+ .globl vdso64_start, vdso64_end
+ .balign PAGE_SIZE
+vdso64_start:
+ .incbin "arch/powerpc/kernel/vdso64/vdso64.so.dbg"
+ .balign PAGE_SIZE
+vdso64_end:
+
+ .previous