[PATCH] arm64: tlb: fix ARM64_TLB_RANGE with LLVM's integrated assembler

Sami Tolvanen
2020-08-05T18:20:20Z

Commit 7c78f67e9bd9 ("arm64: enable tlbi range instructions") breaks
LLVM's integrated assembler, because -Wa,-march is only passed to
external assemblers and therefore, the new instructions are not enabled
when IAS is used.

As binutils doesn't support .arch_extension tlb-rmi, this change adds
.arch armv8.4-a to __TLBI_0 and __TLBI_1 to fix the issue with both LLVM
IAS and binutils.

Fixes: 7c78f67e9bd9 ("arm64: enable tlbi range instructions")
Link: https://github.com/ClangBuiltLinux/linux/issues/1106
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
---
arch/arm64/include/asm/tlbflush.h | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/tlbflush.h b/arch/arm64/include/asm/tlbflush.h
index d493174415db..66c2aab5e9cb 100644
--- a/arch/arm64/include/asm/tlbflush.h
+++ b/arch/arm64/include/asm/tlbflush.h
@@ -16,6 +16,16 @@
#include <asm/cputype.h>
#include <asm/mmu.h>

+/*
+ * Enable ARMv8.4-TLBI instructions with ARM64_TLB_RANGE. Note that binutils
+ * doesn't support .arch_extension tlb-rmi, so use .arch armv8.4-a instead.
+ */
+#ifdef CONFIG_ARM64_TLB_RANGE
+#define __TLBI_PREAMBLE ".arch armv8.4-a\n"
+#else
+#define __TLBI_PREAMBLE
+#endif
+
/*
* Raw TLBI operations.
*
@@ -28,14 +38,16 @@
* not. The macros handles invoking the asm with or without the
* register argument as appropriate.
*/
-#define __TLBI_0(op, arg) asm ("tlbi " #op "\n" \
+#define __TLBI_0(op, arg) asm (__TLBI_PREAMBLE \
+ "tlbi " #op "\n" \
ALTERNATIVE("nop\n nop", \
"dsb ish\n tlbi " #op, \
ARM64_WORKAROUND_REPEAT_TLBI, \
CONFIG_ARM64_WORKAROUND_REPEAT_TLBI) \
: : )

-#define __TLBI_1(op, arg) asm ("tlbi " #op ", %0\n" \
+#define __TLBI_1(op, arg) asm (__TLBI_PREAMBLE \
+ "tlbi " #op ", %0\n" \
ALTERNATIVE("nop\n nop", \
"dsb ish\n tlbi " #op ", %0", \
ARM64_WORKAROUND_REPEAT_TLBI, \

base-commit: 4834ce9d8e074bb7ae197632e0708219b9f389b5
--
2.28.0.163.g6104cc2f0b6-goog