arm64: sysreg: Fix use of XZR in write_sysreg_s

Commit 8a71f0c656e0 ("arm64: sysreg: replace open-coded mrs_s/msr_s with
{read,write}_sysreg_s") introduced a write_sysreg_s macro for writing
to system registers that are not supported by binutils.

Unfortunately, this was implemented with the wrong template (%0 vs %x0),
so in the case that we are writing a constant 0, we will generate
invalid instruction syntax and bail with a cryptic assembler error:

  | Error: constant expression required

This patch fixes the template.

Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
index e8d46e8..6c80b36 100644 (file)
--- a/arch/arm64/include/asm/sysreg.h
+++ b/arch/arm64/include/asm/sysreg.h
@@ -286,7 +286,7 @@ asm(
 
 #define write_sysreg_s(v, r) do {                                      \
        u64 __val = (u64)v;                                             \
-       asm volatile("msr_s " __stringify(r) ", %0" : : "rZ" (__val));  \
+       asm volatile("msr_s " __stringify(r) ", %x0" : : "rZ" (__val)); \
 } while (0)
 
 static inline void config_sctlr_el1(u32 clear, u32 set)