Re: [PATCH bpf v3] x86/cpufeature: bpf hack for clang not supporting asm goto

On Sun, 13 May 2018, Alexei Starovoitov wrote: > On Sat, May 12, 2018 at 10:30:02PM +0200, Thomas Gleixner wrote: > > But yes, the situation is slightly different here because tools which > > create trace event magic _HAVE_ to pull in kernel headers. At the same time > > these tools depend on a

Re: [PATCH bpf v3] x86/cpufeature: bpf hack for clang not supporting asm goto

On Sun, 13 May 2018, Alexei Starovoitov wrote: > On Sat, May 12, 2018 at 10:30:02PM +0200, Thomas Gleixner wrote: > > But yes, the situation is slightly different here because tools which > > create trace event magic _HAVE_ to pull in kernel headers. At the same time > > these tools depend on a

Re: [PATCH bpf v3] x86/cpufeature: bpf hack for clang not supporting asm goto

On Sat, May 12, 2018 at 10:30:02PM +0200, Thomas Gleixner wrote: > On Sat, 12 May 2018, Alexei Starovoitov wrote: > > On Thu, May 10, 2018 at 10:58 AM, Alexei Starovoitov > > wrote: > > > I see no option, but to fix the kernel. > > > Regardless whether it's called

Re: [PATCH bpf v3] x86/cpufeature: bpf hack for clang not supporting asm goto

On Sat, May 12, 2018 at 10:30:02PM +0200, Thomas Gleixner wrote: > On Sat, 12 May 2018, Alexei Starovoitov wrote: > > On Thu, May 10, 2018 at 10:58 AM, Alexei Starovoitov > > wrote: > > > I see no option, but to fix the kernel. > > > Regardless whether it's called user space breakage or kernel

Re: [PATCH bpf v3] x86/cpufeature: bpf hack for clang not supporting asm goto

On Sat, 12 May 2018, Alexei Starovoitov wrote: > On Thu, May 10, 2018 at 10:58 AM, Alexei Starovoitov > wrote: > > I see no option, but to fix the kernel. > > Regardless whether it's called user space breakage or kernel breakage. There is a big difference. If you

Re: [PATCH bpf v3] x86/cpufeature: bpf hack for clang not supporting asm goto

On Sat, 12 May 2018, Alexei Starovoitov wrote: > On Thu, May 10, 2018 at 10:58 AM, Alexei Starovoitov > wrote: > > I see no option, but to fix the kernel. > > Regardless whether it's called user space breakage or kernel breakage. There is a big difference. If you are abusing a kernel internal

Re: [PATCH bpf v3] x86/cpufeature: bpf hack for clang not supporting asm goto

On Thu, May 10, 2018 at 10:58 AM, Alexei Starovoitov wrote: > I see no option, but to fix the kernel. > Regardless whether it's called user space breakage or kernel breakage. Peter, could you please ack the patch or better yet take it into tip tree and send to

Re: [PATCH bpf v3] x86/cpufeature: bpf hack for clang not supporting asm goto

On Thu, May 10, 2018 at 10:58 AM, Alexei Starovoitov wrote: > I see no option, but to fix the kernel. > Regardless whether it's called user space breakage or kernel breakage. Peter, could you please ack the patch or better yet take it into tip tree and send to Linus asap ? rc5 is almost here

Re: [PATCH bpf v3] x86/cpufeature: bpf hack for clang not supporting asm goto

On Thu, May 10, 2018 at 10:58:35AM -0700, Alexei Starovoitov wrote: > libbcc is a library. It's not only used by bcc scripts, but by production > services that compile bpf programs with clang. Let me get this straight: libbcc fails to compile because it includes (through some long include chain)

Re: [PATCH bpf v3] x86/cpufeature: bpf hack for clang not supporting asm goto

On Thu, May 10, 2018 at 10:58:35AM -0700, Alexei Starovoitov wrote: > libbcc is a library. It's not only used by bcc scripts, but by production > services that compile bpf programs with clang. Let me get this straight: libbcc fails to compile because it includes (through some long include chain)

Re: [PATCH bpf v3] x86/cpufeature: bpf hack for clang not supporting asm goto

On Thu, May 10, 2018 at 06:20:28PM +0200, Borislav Petkov wrote: > On Thu, May 10, 2018 at 08:52:42AM -0700, Alexei Starovoitov wrote: > > That makes me wonder what happened with "we do not break user space" rule? > > As someone already pointed out on IRC, arch/x86/include/asm/cpufeature.h > is

Re: [PATCH bpf v3] x86/cpufeature: bpf hack for clang not supporting asm goto

On Thu, May 10, 2018 at 06:20:28PM +0200, Borislav Petkov wrote: > On Thu, May 10, 2018 at 08:52:42AM -0700, Alexei Starovoitov wrote: > > That makes me wonder what happened with "we do not break user space" rule? > > As someone already pointed out on IRC, arch/x86/include/asm/cpufeature.h > is

Re: [PATCH bpf v3] x86/cpufeature: bpf hack for clang not supporting asm goto

On Thu, May 10, 2018 at 9:28 AM Borislav Petkov wrote: > As someone already pointed out on IRC, arch/x86/include/asm/cpufeature.h > is solely a kernel header so nothing but kernel should include it. So > forget the userspace breakage "argument". For what is worth, I have the

Re: [PATCH bpf v3] x86/cpufeature: bpf hack for clang not supporting asm goto

On Thu, May 10, 2018 at 9:28 AM Borislav Petkov wrote: > As someone already pointed out on IRC, arch/x86/include/asm/cpufeature.h > is solely a kernel header so nothing but kernel should include it. So > forget the userspace breakage "argument". For what is worth, I have the same exact problem

Re: [PATCH bpf v3] x86/cpufeature: bpf hack for clang not supporting asm goto

On Thu, May 10, 2018 at 08:52:42AM -0700, Alexei Starovoitov wrote: > That makes me wonder what happened with "we do not break user space" rule? As someone already pointed out on IRC, arch/x86/include/asm/cpufeature.h is solely a kernel header so nothing but kernel should include it. So forget

Re: [PATCH bpf v3] x86/cpufeature: bpf hack for clang not supporting asm goto

On Thu, May 10, 2018 at 08:52:42AM -0700, Alexei Starovoitov wrote: > That makes me wonder what happened with "we do not break user space" rule? As someone already pointed out on IRC, arch/x86/include/asm/cpufeature.h is solely a kernel header so nothing but kernel should include it. So forget

Re: [PATCH bpf v3] x86/cpufeature: bpf hack for clang not supporting asm goto

On Thu, May 10, 2018 at 12:06:34PM +0200, Peter Zijlstra wrote: > On Thu, May 03, 2018 at 08:31:19PM -0700, Yonghong Song wrote: > > > This approach is preferred since the already deployed bcc scripts, or > > any other bpf applicaitons utilizing LLVM JIT compilation functionality, > > will

Re: [PATCH bpf v3] x86/cpufeature: bpf hack for clang not supporting asm goto

On Thu, May 10, 2018 at 12:06:34PM +0200, Peter Zijlstra wrote: > On Thu, May 03, 2018 at 08:31:19PM -0700, Yonghong Song wrote: > > > This approach is preferred since the already deployed bcc scripts, or > > any other bpf applicaitons utilizing LLVM JIT compilation functionality, > > will

Re: [PATCH bpf v3] x86/cpufeature: bpf hack for clang not supporting asm goto

On Thu, May 03, 2018 at 08:31:19PM -0700, Yonghong Song wrote: > Commit d0266046ad54 ("x86: Remove FAST_FEATURE_TESTS") > removed X86_FAST_FEATURE_TESTS and make macro static_cpu_has() always > use __always_inline function _static_cpu_has() funciton. > The static_cpu_has() uses gcc feature asm

Re: [PATCH bpf v3] x86/cpufeature: bpf hack for clang not supporting asm goto

On Thu, May 03, 2018 at 08:31:19PM -0700, Yonghong Song wrote: > Commit d0266046ad54 ("x86: Remove FAST_FEATURE_TESTS") > removed X86_FAST_FEATURE_TESTS and make macro static_cpu_has() always > use __always_inline function _static_cpu_has() funciton. > The static_cpu_has() uses gcc feature asm

Re: [PATCH bpf v3] x86/cpufeature: bpf hack for clang not supporting asm goto

On Thu, May 03, 2018 at 08:31:19PM -0700, Yonghong Song wrote: > This approach is preferred since the already deployed bcc scripts, or > any other bpf applicaitons utilizing LLVM JIT compilation functionality, > will continue work with the new kernel without re-compilation and > re-deployment.

Re: [PATCH bpf v3] x86/cpufeature: bpf hack for clang not supporting asm goto

On Thu, May 03, 2018 at 08:31:19PM -0700, Yonghong Song wrote: > This approach is preferred since the already deployed bcc scripts, or > any other bpf applicaitons utilizing LLVM JIT compilation functionality, > will continue work with the new kernel without re-compilation and > re-deployment.

[PATCH bpf v3] x86/cpufeature: bpf hack for clang not supporting asm goto

Commit d0266046ad54 ("x86: Remove FAST_FEATURE_TESTS") removed X86_FAST_FEATURE_TESTS and make macro static_cpu_has() always use __always_inline function _static_cpu_has() funciton. The static_cpu_has() uses gcc feature asm goto construct, which is not supported by clang. Issues ==

[PATCH bpf v3] x86/cpufeature: bpf hack for clang not supporting asm goto

Commit d0266046ad54 ("x86: Remove FAST_FEATURE_TESTS") removed X86_FAST_FEATURE_TESTS and make macro static_cpu_has() always use __always_inline function _static_cpu_has() funciton. The static_cpu_has() uses gcc feature asm goto construct, which is not supported by clang. Issues ==