From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Michael Ellerman <mpe@ellerman.id.au>,
Nick Desaulniers <ndesaulniers@google.com>,
Sasha Levin <sashal@kernel.org>,
benh@kernel.crashing.org, paulus@samba.org,
linuxppc-dev@lists.ozlabs.org
Subject: [PATCH AUTOSEL 4.14 14/14] powerpc/dcr: Use cmplwi instead of 3-argument cmpli
Date: Tue, 9 Nov 2021 17:23:43 -0500 [thread overview]
Message-ID: <20211109222343.1235902-14-sashal@kernel.org> (raw)
In-Reply-To: <20211109222343.1235902-1-sashal@kernel.org>
From: Michael Ellerman <mpe@ellerman.id.au>
[ Upstream commit fef071be57dc43679a32d5b0e6ee176d6f12e9f2 ]
In dcr-low.S we use cmpli with three arguments, instead of four
arguments as defined in the ISA:
cmpli cr0,r3,1024
This appears to be a PPC440-ism, looking at the "PPC440x5 CPU Core
User’s Manual" it shows cmpli having no L field, but implied to be 0 due
to the core being 32-bit. It mentions that the ISA defines four
arguments and recommends using cmplwi.
It also corresponds to the old POWER instruction set, which had no L
field there, a reserved bit instead.
dcr-low.S is only built 32-bit, because it is only built when
DCR_NATIVE=y, which is only selected by 40x and 44x. Looking at the
generated code (with gcc/gas) we see cmplwi as expected.
Although gas is happy with the 3-argument version when building for
32-bit, the LLVM assembler is not and errors out with:
arch/powerpc/sysdev/dcr-low.S:27:10: error: invalid operand for instruction
cmpli 0,%r3,1024; ...
^
Switch to the cmplwi extended opcode, which avoids any confusion when
reading the ISA, fixes the issue with the LLVM assembler, and also means
the code could be built 64-bit in future (though that's very unlikely).
Reported-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
BugLink: https://github.com/ClangBuiltLinux/linux/issues/1419
Link: https://lore.kernel.org/r/20211014024424.528848-1-mpe@ellerman.id.au
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/powerpc/sysdev/dcr-low.S | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/powerpc/sysdev/dcr-low.S b/arch/powerpc/sysdev/dcr-low.S
index e687bb2003ff0..5589fbe48bbdc 100644
--- a/arch/powerpc/sysdev/dcr-low.S
+++ b/arch/powerpc/sysdev/dcr-low.S
@@ -15,7 +15,7 @@
#include <asm/export.h>
#define DCR_ACCESS_PROLOG(table) \
- cmpli cr0,r3,1024; \
+ cmplwi cr0,r3,1024; \
rlwinm r3,r3,4,18,27; \
lis r5,table@h; \
ori r5,r5,table@l; \
--
2.33.0
prev parent reply other threads:[~2021-11-09 22:42 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-09 22:23 [PATCH AUTOSEL 4.14 01/14] arm64: zynqmp: Fix serial compatible string Sasha Levin
2021-11-09 22:23 ` [PATCH AUTOSEL 4.14 02/14] scsi: lpfc: Fix list_add() corruption in lpfc_drain_txq() Sasha Levin
2021-11-09 22:23 ` [PATCH AUTOSEL 4.14 03/14] arm64: dts: rockchip: add Coresight debug range for RK3399 Sasha Levin
2021-11-09 22:23 ` [PATCH AUTOSEL 4.14 04/14] usb: musb: tusb6010: check return value after calling platform_get_resource() Sasha Levin
2021-11-09 22:23 ` [PATCH AUTOSEL 4.14 05/14] scsi: advansys: Fix kernel pointer leak Sasha Levin
2021-11-09 22:23 ` [PATCH AUTOSEL 4.14 06/14] ARM: dts: omap: fix gpmc,mux-add-data type Sasha Levin
2021-11-09 22:23 ` [PATCH AUTOSEL 4.14 07/14] usb: host: ohci-tmio: check return value after calling platform_get_resource() Sasha Levin
2021-11-09 22:23 ` [PATCH AUTOSEL 4.14 08/14] tty: tty_buffer: Fix the softlockup issue in flush_to_ldisc Sasha Levin
2021-11-09 22:23 ` [PATCH AUTOSEL 4.14 09/14] MIPS: sni: Fix the build Sasha Levin
2021-11-09 22:23 ` [PATCH AUTOSEL 4.14 10/14] scsi: target: Fix ordered tag handling Sasha Levin
2021-11-09 22:23 ` [PATCH AUTOSEL 4.14 11/14] scsi: target: Fix alua_tg_pt_gps_count tracking Sasha Levin
2021-11-09 22:23 ` [PATCH AUTOSEL 4.14 12/14] powerpc/5200: dts: fix memory node unit name Sasha Levin
2021-11-09 22:23 ` [PATCH AUTOSEL 4.14 13/14] ALSA: gus: fix null pointer dereference on pointer block Sasha Levin
2021-11-09 22:23 ` Sasha Levin [this message]
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