linux-kernel - [PATCH] x86/entry: add compatibility with IAS

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Date:   Sun, 12 Jul 2020 18:24:22 -0700
From:   Jian Cai <caij2003@...il.com>
To:     unlisted-recipients:; (no To-header on input)
Cc:     caij2003@...il.com, jiancai@...gle.com, ndesaulniers@...gle.com,
        manojgupta@...gle.com, sedat.dilek@...il.com,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Alexandre Chartre <alexandre.chartre@...cle.com>,
        linux-kernel@...r.kernel.org, clang-built-linux@...glegroups.com
Subject: [PATCH] x86/entry: add compatibility with IAS

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 <ndesaulniers@...gle.com>
Reported-by: Sedat Dilek <sedat.dilek@...il.com>
Suggested-by: Nick Desaulniers <ndesaulniers@...gle.com>
Tested-by: Sedat Dilek <sedat.dilek@...il.com>
Signed-off-by: Jian Cai <caij2003@...il.com>
---
 arch/x86/include/asm/idtentry.h | 22 ++++++++++------------
 1 file changed, 10 insertions(+), 12 deletions(-)

diff --git a/arch/x86/include/asm/idtentry.h b/arch/x86/include/asm/idtentry.h
index f3d70830bf2a..77beed2cd6d9 100644
--- a/arch/x86/include/asm/idtentry.h
+++ b/arch/x86/include/asm/idtentry.h
@@ -468,34 +468,32 @@ __visible noinstr void func(struct pt_regs *regs,			\
  */
 	.align 8
 SYM_CODE_START(irq_entries_start)
-    vector=FIRST_EXTERNAL_VECTOR
-    pos = .
+    i = 1
+    pos1 = .
     .rept (FIRST_SYSTEM_VECTOR - FIRST_EXTERNAL_VECTOR)
 	UNWIND_HINT_IRET_REGS
-	.byte	0x6a, vector
+	.byte	0x6a, FIRST_EXTERNAL_VECTOR + i - 1
 	jmp	asm_common_interrupt
 	nop
 	/* Ensure that the above is 8 bytes max */
-	. = pos + 8
-    pos=pos+8
-    vector=vector+1
+	. = pos1 + 8 * i
+	i = i + 1
     .endr
 SYM_CODE_END(irq_entries_start)
 
 #ifdef CONFIG_X86_LOCAL_APIC
 	.align 8
 SYM_CODE_START(spurious_entries_start)
-    vector=FIRST_SYSTEM_VECTOR
-    pos = .
+    i = 1
+    pos2 = .
     .rept (NR_VECTORS - FIRST_SYSTEM_VECTOR)
 	UNWIND_HINT_IRET_REGS
-	.byte	0x6a, vector
+	.byte	0x6a, FIRST_SYSTEM_VECTOR + i - 1
 	jmp	asm_spurious_interrupt
 	nop
 	/* Ensure that the above is 8 bytes max */
-	. = pos + 8
-    pos=pos+8
-    vector=vector+1
+	. = pos2 + 8 * i
+	i = i + 1
     .endr
 SYM_CODE_END(spurious_entries_start)
 #endif
-- 
2.27.0.383.g050319c2ae-goog