Patch "riscv: vdso: fix build with llvm" has been added to the 6.0-stable tree

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This is a note to let you know that I've just added the patch titled

    riscv: vdso: fix build with llvm

to the 6.0-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     riscv-vdso-fix-build-with-llvm.patch
and it can be found in the queue-6.0 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit a3cd1a6dad095f3aaf9109eba1138119622ed5b2
Author: Jisheng Zhang <jszhang@xxxxxxxxxx>
Date:   Tue Nov 1 02:29:43 2022 +0800

    riscv: vdso: fix build with llvm
    
    [ Upstream commit 50f4dd657a0fcf90aa8da8dc2794a8100ff4c37c ]
    
    Even after commit 89fd4a1df829 ("riscv: jump_label: mark arguments as
    const to satisfy asm constraints"), building with CC_OPTIMIZE_FOR_SIZE
    + LLVM=1 can reproduce below build error:
    
      CC      arch/riscv/kernel/vdso/vgettimeofday.o
    In file included from <built-in>:4:
    In file included from lib/vdso/gettimeofday.c:5:
    In file included from include/vdso/datapage.h:17:
    In file included from include/vdso/processor.h:10:
    In file included from arch/riscv/include/asm/vdso/processor.h:7:
    In file included from include/linux/jump_label.h:112:
    arch/riscv/include/asm/jump_label.h:42:3: error:
    invalid operand for inline asm constraint 'i'
                    "       .option push                            \n\t"
                    ^
    1 error generated.
    
    I think the problem is when "-Os" is passed as CFLAGS, it's removed by
    "CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) -Os" which is
    introduced in commit e05d57dcb8c7 ("riscv: Fixup __vdso_gettimeofday
    broke dynamic ftrace"), thus no optimization at all for vgettimeofday.c
    arm64 does remove "-Os" as well, but it forces "-O2" after removing
    "-Os".
    
    I compared the generated vgettimeofday.o with "-O2" and "-Os",
    I think no big performance difference. So let's tell the kbuild not
    to remove "-Os" rather than follow arm64 style.
    
    vdso related performance can be improved a lot when building kernel with
    CC_OPTIMIZE_FOR_SIZE after this commit, ("-Os" VS no optimization)
    
    Fixes: e05d57dcb8c7 ("riscv: Fixup __vdso_gettimeofday broke dynamic ftrace")
    Signed-off-by: Jisheng Zhang <jszhang@xxxxxxxxxx>
    Tested-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
    Link: https://lore.kernel.org/r/20221031182943.2453-1-jszhang@xxxxxxxxxx
    Signed-off-by: Palmer Dabbelt <palmer@xxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/arch/riscv/kernel/vdso/Makefile b/arch/riscv/kernel/vdso/Makefile
index f2e065671e4d..84ac0fe612e7 100644
--- a/arch/riscv/kernel/vdso/Makefile
+++ b/arch/riscv/kernel/vdso/Makefile
@@ -30,7 +30,7 @@ obj-y += vdso.o
 CPPFLAGS_vdso.lds += -P -C -U$(ARCH)
 
 # Disable -pg to prevent insert call site
-CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) -Os
+CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE)
 
 # Disable profiling and instrumentation for VDSO code
 GCOV_PROFILE := n



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