kernel.git/arch/x86/entry/vdso, branch linux-4.18.y

x86/vdso: Fix vDSO syscall fallback asm constraint regression

2018-10-13T07:33:13Z

commit 02e425668f5c9deb42787d10001a3b605993ad15 upstream. When I added the missing memory outputs, I failed to update the index of the first argument (ebx) on 32-bit builds, which broke the fallbacks. Somehow I must have screwed up my testing or gotten lucky. Add another test to cover gettimeofday() as well. Signed-off-by: Andy Lutomirski Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: stable@vger.kernel.org Fixes: 715bd9d12f84 ("x86/vdso: Fix asm constraints on vDSO syscall fallbacks") Link: http://lkml.kernel.org/r/21bd45ab04b6d838278fa5bebfa9163eceffa13c.1538608971.git.luto@kernel.org Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman

x86/vdso: Only enable vDSO retpolines when enabled and supported

2018-10-13T07:33:13Z

commit 4f166564014aba65ad6f15b612f6711fd0f117ee upstream. When I fixed the vDSO build to use inline retpolines, I messed up the Makefile logic and made it unconditional. It should have depended on CONFIG_RETPOLINE and on the availability of compiler support. This broke the build on some older compilers. Reported-by: nikola.ciprich@linuxbox.cz Signed-off-by: Andy Lutomirski Cc: Borislav Petkov Cc: David Woodhouse Cc: Linus Torvalds Cc: Matt Rickard Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: jason.vas.dias@gmail.com Cc: stable@vger.kernel.org Fixes: 2e549b2ee0e3 ("x86/vdso: Fix vDSO build if a retpoline is emitted") Link: http://lkml.kernel.org/r/08a1f29f2c238dd1f493945e702a521f8a5aa3ae.1538540801.git.luto@kernel.org Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman

x86/vdso: Fix asm constraints on vDSO syscall fallbacks

2018-10-13T07:33:12Z

commit 715bd9d12f84d8f5cc8ad21d888f9bc304a8eb0b upstream. The syscall fallbacks in the vDSO have incorrect asm constraints. They are not marked as writing to their outputs -- instead, they are marked as clobbering "memory", which is useless. In particular, gcc is smart enough to know that the timespec parameter hasn't escaped, so a memory clobber doesn't clobber it. And passing a pointer as an asm *input* does not tell gcc that the pointed-to value is changed. Add in the fact that the asm instructions weren't volatile, and gcc was free to omit them entirely unless their sole output (the return value) is used. Which it is (phew!), but that stops happening with some upcoming patches. As a trivial example, the following code: void test_fallback(struct timespec *ts) { vdso_fallback_gettime(CLOCK_MONOTONIC, ts); } compiles to: 00000000000000c0 : c0: c3 retq To add insult to injury, the RCX and R11 clobbers on 64-bit builds were missing. The "memory" clobber is also unnecessary -- no ordering with respect to other memory operations is needed, but that's going to be fixed in a separate not-for-stable patch. Fixes: 2aae950b21e4 ("x86_64: Add vDSO for x86-64 with gettimeofday/clock_gettime/getcpu") Signed-off-by: Andy Lutomirski Signed-off-by: Thomas Gleixner Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/2c0231690551989d2fafa60ed0e7b5cc8b403908.1538422295.git.luto@kernel.org Signed-off-by: Greg Kroah-Hartman

x86/vdso: Fix vDSO build if a retpoline is emitted

2018-09-05T07:29:48Z

commit 2e549b2ee0e358bc758480e716b881f9cabedb6a upstream. Currently, if the vDSO ends up containing an indirect branch or call, GCC will emit the "external thunk" style of retpoline, and it will fail to link. Fix it by building the vDSO with inline retpoline thunks. I haven't seen any reports of this triggering on an unpatched kernel. Fixes: commit 76b043848fd2 ("x86/retpoline: Add initial retpoline support") Signed-off-by: Andy Lutomirski Signed-off-by: Thomas Gleixner Acked-by: Matt Rickard Cc: Borislav Petkov Cc: Jason Vas Dias Cc: David Woodhouse Cc: Peter Zijlstra Cc: Andi Kleen Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/c76538cd3afbe19c6246c2d1715bc6a60bd63985.1534448381.git.luto@kernel.org Signed-off-by: Greg Kroah-Hartman

Merge branch 'x86-build-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2018-06-05T02:16:16Z

Pull x86 build updates from Ingo Molnar: "A handful of build system (Makefile, linker script) cleanups by Masahiro Yamada" * 'x86-build-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/build/vdso: Put generated linker scripts to $(obj)/ x86/build/vdso: Remove unnecessary export in Makefile x86/build/vdso: Remove unused $(vobjs-nox32) in Makefile x86/build: Remove no-op macro VMLINUX_SYMBOL()

x86/build/vdso: Put generated linker scripts to $(obj)/

2018-05-15T05:32:42Z

Let's put generated files to $(obj)/ rather than $(src)/ although this is just a matter of taste because both are the same. Signed-off-by: Masahiro Yamada Cc: Andy Lutomirski Cc: Jeff Dike Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Richard Weinberger Cc: Thomas Gleixner Cc: user-mode-linux-devel@lists.sourceforge.net Cc: user-mode-linux-user@lists.sourceforge.net Link: http://lkml.kernel.org/r/1526352744-28229-4-git-send-email-yamada.masahiro@socionext.com Signed-off-by: Ingo Molnar

x86/build/vdso: Remove unnecessary export in Makefile

2018-05-15T05:32:42Z

CPPFLAGS_vdso.lds is assigned and referenced internally in each Makefile. No need to export it. Signed-off-by: Masahiro Yamada Cc: Andy Lutomirski Cc: Jeff Dike Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Richard Weinberger Cc: Thomas Gleixner Cc: user-mode-linux-devel@lists.sourceforge.net Cc: user-mode-linux-user@lists.sourceforge.net Link: http://lkml.kernel.org/r/1526352744-28229-3-git-send-email-yamada.masahiro@socionext.com Signed-off-by: Ingo Molnar

x86/build/vdso: Remove unused $(vobjs-nox32) in Makefile

2018-05-15T05:32:42Z

Since commit bfad381c0d1e ("x86/vdso: Improve the fake section headers"), $(vobjs-nox32) is empty. Therefore, $(vobjs64-for-x32) is the same as $(vobjs-y). Signed-off-by: Masahiro Yamada Cc: Andy Lutomirski Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1526352744-28229-2-git-send-email-yamada.masahiro@socionext.com Signed-off-by: Ingo Molnar

x86/vdso: Remove unused file

2018-05-05T07:02:36Z

commit da861e18eccc ("x86, vdso: Get rid of the fake section mechanism") left this file behind; nothing is using it anymore. Signed-off-by: Jann Horn Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: luto@amacapital.net Link: http://lkml.kernel.org/r/20180504175935.104085-1-jannh@google.com Signed-off-by: Ingo Molnar

kbuild: mark $(targets) as .SECONDARY and remove .PRECIOUS markers

2018-04-07T10:04:02Z

GNU Make automatically deletes intermediate files that are updated in a chain of pattern rules. Example 1) %.dtb.o <- %.dtb.S <- %.dtb <- %.dts Example 2) %.o <- %.c <- %.c_shipped A couple of makefiles mark such targets as .PRECIOUS to prevent Make from deleting them, but the correct way is to use .SECONDARY. .SECONDARY Prerequisites of this special target are treated as intermediate files but are never automatically deleted. .PRECIOUS When make is interrupted during execution, it may delete the target file it is updating if the file was modified since make started. If you mark the file as precious, make will never delete the file if interrupted. Both can avoid deletion of intermediate files, but the difference is the behavior when Make is interrupted; .SECONDARY deletes the target, but .PRECIOUS does not. The use of .PRECIOUS is relatively rare since we do not want to keep partially constructed (possibly corrupted) targets. Another difference is that .PRECIOUS works with pattern rules whereas .SECONDARY does not. .PRECIOUS: $(obj)/%.lex.c works, but .SECONDARY: $(obj)/%.lex.c has no effect. However, for the reason above, I do not want to use .PRECIOUS which could cause obscure build breakage. The targets specified as .SECONDARY must be explicit. $(targets) contains all targets that need to include .*.cmd files. So, the intermediates you want to keep are mostly in there. Therefore, mark $(targets) as .SECONDARY. It means primary targets are also marked as .SECONDARY, but I do not see any drawback for this. I replaced some .SECONDARY / .PRECIOUS markers with 'targets'. This will make Kbuild search for non-existing .*.cmd files, but this is not a noticeable performance issue. Signed-off-by: Masahiro Yamada Acked-by: Frank Rowand Acked-by: Ingo Molnar