The following build warning happens on gcc 8.1.0.
linux/arch/arm64/include/asm/insn.h: In function 'aarch64_insn_is_ldadd':
linux/arch/arm64/include/asm/insn.h:280:257: warning: bitwise comparison always evaluates to false [-Wtautological-compare]
__AARCH64_INSN_FUNCS(ldadd, 0x3F20FC00, 0xB8200000)
Since the second argument is mask value and compare with the third
argument value, the bit 31 is always masked and then this macro is
always false. So, this patch fixes the issue.
Reported-by: Kuninori Morimoto <kuninori.morimoto.gx@xxxxxxxxxxx>
Fixes: 34b8ab091f9ef57a ("bpf, arm64: use more scalable stadd over ldxr / stxr loop in xadd")
Tested-by: Kuninori Morimoto <kuninori.morimoto.gx@xxxxxxxxxxx>
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
---
I'm not sure the second argument "0xBF20FC00" is OK or not (we can set
to 0xFF20FC00 instead). So, I marked RFC on this patch.
arch/arm64/include/asm/insn.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arm64/include/asm/insn.h b/arch/arm64/include/asm/insn.h
index ec894de..c9e3cdc 100644
--- a/arch/arm64/include/asm/insn.h
+++ b/arch/arm64/include/asm/insn.h
@@ -277,7 +277,7 @@ __AARCH64_INSN_FUNCS(adrp, 0x9F000000, 0x90000000)
__AARCH64_INSN_FUNCS(prfm, 0x3FC00000, 0x39800000)
__AARCH64_INSN_FUNCS(prfm_lit, 0xFF000000, 0xD8000000)
__AARCH64_INSN_FUNCS(str_reg, 0x3FE0EC00, 0x38206800)
-__AARCH64_INSN_FUNCS(ldadd, 0x3F20FC00, 0xB8200000)
+__AARCH64_INSN_FUNCS(ldadd, 0xBF20FC00, 0xB8200000)
__AARCH64_INSN_FUNCS(ldr_reg, 0x3FE0EC00, 0x38606800)
__AARCH64_INSN_FUNCS(ldr_lit, 0xBF000000, 0x18000000)
__AARCH64_INSN_FUNCS(ldrsw_lit, 0xFF000000, 0x98000000)
--
2.7.4
