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From: Heiko Stuebner <heiko@sntech.de>
To: palmer@dabbelt.com, paul.walmsley@sifive.com, aou@eecs.berkeley.edu
Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
	wefu@redhat.com, liush@allwinnertech.com, guoren@kernel.org,
	atishp@atishpatra.org, anup@brainfault.org, drew@beagleboard.org,
	hch@lst.de, arnd@arndb.de, wens@csie.org, maxime@cerno.tech,
	gfavor@ventanamicro.com, andrea.mondelli@huawei.com,
	behrensj@mit.edu, xinhaoqu@huawei.com, mick@ics.forth.gr,
	allen.baum@esperantotech.com, jscheid@ventanamicro.com,
	rtrauben@gmail.com, samuel@sholland.org, cmuellner@linux.com,
	philipp.tomsich@vrull.eu, Heiko Stuebner <heiko@sntech.de>
Subject: [PATCH 06/12] riscv: prevent compressed instructions in alternatives
Date: Wed, 11 May 2022 21:29:15 +0200	[thread overview]
Message-ID: <20220511192921.2223629-7-heiko@sntech.de> (raw)
In-Reply-To: <20220511192921.2223629-1-heiko@sntech.de>

Instructions are opportunistically compressed by the RISC-V assembler
when possible, but in alternatives-blocks both the old and new content
need to be the same size, so having the toolchain do somewhat random
optimizations will cause strange side-effects like
"attempt to move .org backwards" compile-time errors.

Already a simple "and" used in alternatives assembly will cause these
mismatched code sizes.

So prevent compressed instructions to be generated in alternatives-
code and use option-push and -pop to only limit this to the relevant
code blocks

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Philipp Tomsich <philipp.tomsich@vrull.eu>
---
 arch/riscv/include/asm/alternative-macros.h | 24 +++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/arch/riscv/include/asm/alternative-macros.h b/arch/riscv/include/asm/alternative-macros.h
index 8c2bbc7bbe50..e13b1f6bb400 100644
--- a/arch/riscv/include/asm/alternative-macros.h
+++ b/arch/riscv/include/asm/alternative-macros.h
@@ -21,7 +21,11 @@
 	.popsection
 	.subsection 1
 888 :
+	.option push
+	.option norvc
+	.option norelax
 	\new_c
+	.option pop
 889 :
 	.previous
 	.org    . - (889b - 888b) + (887b - 886b)
@@ -31,7 +35,11 @@
 
 .macro __ALTERNATIVE_CFG old_c, new_c, vendor_id, errata_id, enable
 886 :
+	.option push
+	.option norvc
+	.option norelax
 	\old_c
+	.option pop
 887 :
 	ALT_NEW_CONTENT \vendor_id, \errata_id, \enable, \new_c
 .endm
@@ -42,7 +50,11 @@
 .macro __ALTERNATIVE_CFG_2 old_c, new_c_1, vendor_id_1, errata_id_1, enable_1, \
 				  new_c_2, vendor_id_2, errata_id_2, enable_2
 886 :
+	.option push
+	.option norvc
+	.option norelax
 	\old_c
+	.option pop
 887 :
 	ALT_NEW_CONTENT \vendor_id_1, \errata_id_1, \enable_1, \new_c_1
 	ALT_NEW_CONTENT \vendor_id_2, \errata_id_2, \enable_2, \new_c_2
@@ -76,7 +88,11 @@
 	".popsection\n"							\
 	".subsection 1\n"						\
 	"888 :\n"							\
+	".option push\n"						\
+	".option norvc\n"						\
+	".option norelax\n"						\
 	new_c "\n"							\
+	".option pop\n"							\
 	"889 :\n"							\
 	".previous\n"							\
 	".org	. - (887b - 886b) + (889b - 888b)\n"			\
@@ -85,7 +101,11 @@
 
 #define __ALTERNATIVE_CFG(old_c, new_c, vendor_id, errata_id, enable)	\
 	"886 :\n"							\
+	".option push\n"						\
+	".option norvc\n"						\
+	".option norelax\n"						\
 	old_c "\n"							\
+	".option pop\n"							\
 	"887 :\n"							\
 	ALT_NEW_CONTENT(vendor_id, errata_id, enable, new_c)
 
@@ -97,7 +117,11 @@
 				   new_c_2, vendor_id_2, errata_id_2,	\
 					enable_2)			\
 	"886 :\n"							\
+	".option push\n"						\
+	".option norvc\n"						\
+	".option norelax\n"						\
 	old_c "\n"							\
+	".option pop\n"							\
 	"887 :\n"							\
 	ALT_NEW_CONTENT(vendor_id_1, errata_id_1, enable_1, new_c_1)	\
 	ALT_NEW_CONTENT(vendor_id_2, errata_id_2, enable_2, new_c_2)
-- 
2.35.1


  parent reply	other threads:[~2022-05-11 19:30 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-11 19:29 [PATCH v10 00/12] riscv: support for Svpbmt and D1 memory types Heiko Stuebner
2022-05-11 19:29 ` [PATCH 01/12] riscv: integrate alternatives better into the main architecture Heiko Stuebner
2022-05-16  6:01   ` Christoph Hellwig
2022-05-16  6:45   ` Guo Ren
2022-05-11 19:29 ` [PATCH 02/12] riscv: allow different stages with alternatives Heiko Stuebner
2022-05-16  6:01   ` Christoph Hellwig
2022-05-16  6:51   ` Guo Ren
2022-05-11 19:29 ` [PATCH 03/12] riscv: implement module alternatives Heiko Stuebner
2022-05-16  6:02   ` Christoph Hellwig
2022-05-16  6:54   ` Guo Ren
2022-05-11 19:29 ` [PATCH 04/12] riscv: implement ALTERNATIVE_2 macro Heiko Stuebner
2022-05-16  6:03   ` Christoph Hellwig
2022-05-16  6:54   ` Guo Ren
2022-05-11 19:29 ` [PATCH 05/12] riscv: extend concatenated alternatives-lines to the same length Heiko Stuebner
2022-05-16  6:03   ` Christoph Hellwig
2022-05-16  6:55   ` Guo Ren
2022-05-11 19:29 ` Heiko Stuebner [this message]
2022-05-16  6:04   ` [PATCH 06/12] riscv: prevent compressed instructions in alternatives Christoph Hellwig
2022-05-16  6:55   ` Guo Ren
2022-05-11 19:29 ` [PATCH 07/12] riscv: move boot alternatives to after fill_hwcap Heiko Stuebner
2022-05-11 19:29 ` [PATCH 08/12] riscv: Fix accessing pfn bits in PTEs for non-32bit variants Heiko Stuebner
2022-05-16  6:04   ` Christoph Hellwig
2022-05-16  6:55   ` Guo Ren
2022-05-23 14:03   ` Alexandre Ghiti
2022-05-25 15:22     ` Heiko Stübner
2022-05-28  8:15       ` Alexandre Ghiti
2022-05-11 19:29 ` [PATCH 09/12] riscv: add RISC-V Svpbmt extension support Heiko Stuebner
2022-05-16  6:10   ` Christoph Hellwig
2022-05-16  9:09     ` Philipp Tomsich
2022-05-16 10:30       ` Heiko Stübner
2022-05-11 19:29 ` [PATCH 10/12] riscv: remove FIXMAP_PAGE_IO and fall back to its default value Heiko Stuebner
2022-05-11 19:29 ` [PATCH 11/12] riscv: don't use global static vars to store alternative data Heiko Stuebner
2022-05-16  6:15   ` Christoph Hellwig
2022-05-11 19:29 ` [PATCH 12/12] riscv: add memory-type errata for T-Head Heiko Stuebner
2022-05-13 13:37   ` Guo Ren
2022-05-13  3:32 ` [PATCH v10 00/12] riscv: support for Svpbmt and D1 memory types Palmer Dabbelt
2022-05-13 21:41   ` Heiko Stuebner

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