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Peter Anvin" , Andy Lutomirski , Peter Zijlstra , Alexandre Chartre , linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com Subject: Re: [PATCH] x86/entry: add compatibility with IAS Message-ID: <20200713221736.GA1904448@rani.riverdale.lan> References: <20200713012428.1039487-1-caij2003@gmail.com> <20200713213803.1274795-1-caij2003@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20200713213803.1274795-1-caij2003@gmail.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 13, 2020 at 02:38:01PM -0700, Jian Cai wrote: > Clang's integrated assembler does not allow symbols with non-absolute > values to be reassigned. This patch allows the affected code to be > compatible with IAS. > > Link: https://github.com/ClangBuiltLinux/linux/issues/1043 > Reported-by: Nick Desaulniers > Reported-by: Sedat Dilek > Suggested-by: Nick Desaulniers > Suggested-by: Brian Gerst > Suggested-by: Arvind Sankar > Tested-by: Sedat Dilek > Signed-off-by: Jian Cai > --- > arch/x86/include/asm/idtentry.h | 16 +++++++--------- > 1 file changed, 7 insertions(+), 9 deletions(-) > > diff --git a/arch/x86/include/asm/idtentry.h b/arch/x86/include/asm/idtentry.h > index f3d70830bf2a..7d22684eafdf 100644 > --- a/arch/x86/include/asm/idtentry.h > +++ b/arch/x86/include/asm/idtentry.h > @@ -469,16 +469,15 @@ __visible noinstr void func(struct pt_regs *regs, \ > .align 8 > SYM_CODE_START(irq_entries_start) > vector=FIRST_EXTERNAL_VECTOR > - pos = . > .rept (FIRST_SYSTEM_VECTOR - FIRST_EXTERNAL_VECTOR) > +0 : > UNWIND_HINT_IRET_REGS I know I had it this way, but I think it may be slightly safer to put the label immediately after UNWIND_HINT_IRET_REGS instead of before, just in case anyone adds a 0: inside that macro.