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From: Andrey Smirnov <andrew.smirnov@gmail.com>
To: barebox@lists.infradead.org
Cc: Andrey Smirnov <andrew.smirnov@gmail.com>,
	Chris Healy <cphealy@gmail.com>,
	Heiner Kallweit <hkallweit1@gmail.com>
Subject: [PATCH 1/3] ARM: zii-vf610-dev: Use -fno-tree-switch-conversion -fno-jump-tables
Date: Sun, 14 Apr 2019 17:21:19 -0700	[thread overview]
Message-ID: <20190415002121.15988-1-andrew.smirnov@gmail.com> (raw)

Original and very poor workaround no longer works against GCC8, so
drop it and replace with a proper solution that should've been used in
the first place - specifying -fno-tree-switch-conversion
-fno-jump-tables as CFLAGS when building lowlevel.c

Tested to work with:

    - GCC 8.2.1 (arm-none-eabi)
    - GCC 7.1.0 (arm-none-eabi)
    - GCC 4.8.4 (armv7l-timesys-linux-gnueabihf)

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Cc: Heiner Kallweit <hkallweit1@gmail.com>
Cc: Chris Healy <cphealy@gmail.com>
---
 arch/arm/boards/zii-vf610-dev/Makefile   |  1 +
 arch/arm/boards/zii-vf610-dev/lowlevel.c | 17 -----------------
 2 files changed, 1 insertion(+), 17 deletions(-)

diff --git a/arch/arm/boards/zii-vf610-dev/Makefile b/arch/arm/boards/zii-vf610-dev/Makefile
index 1297d815e..3c3a3f238 100644
--- a/arch/arm/boards/zii-vf610-dev/Makefile
+++ b/arch/arm/boards/zii-vf610-dev/Makefile
@@ -1,3 +1,4 @@
 obj-y += board.o
+CFLAGS_pbl-lowlevel.o := -fno-tree-switch-conversion -fno-jump-tables
 lwl-y += lowlevel.o
 bbenv-y += defaultenv-zii-vf610-dev
diff --git a/arch/arm/boards/zii-vf610-dev/lowlevel.c b/arch/arm/boards/zii-vf610-dev/lowlevel.c
index a1859eeae..b320fbc0c 100644
--- a/arch/arm/boards/zii-vf610-dev/lowlevel.c
+++ b/arch/arm/boards/zii-vf610-dev/lowlevel.c
@@ -95,23 +95,6 @@ ENTRY_FUNCTION(start_zii_vf610_dev, r0, r1, r2)
 
 	switch (system_type) {
 	default:
-		/*
-		 * GCC can be smart enough to, when DEBUG_LL is
-		 * disabled, reduce this switch statement to a LUT
-		 * fetch. Unfortunately here, this early in the boot
-		 * process before any relocation/address fixups could
-		 * happen, the address of that LUT used by the code is
-		 * incorrect and any access to it would result in
-		 * bogus values.
-		 *
-		 * Adding the following barrier() statement seem to
-		 * force the compiler to always translate this block
-		 * to a sequence of consecutive checks and jumps with
-		 * relative fetches, which should work with or without
-		 * relocation/fixups.
-		 */
-		barrier();
-
 		if (IS_ENABLED(CONFIG_DEBUG_LL)) {
 			relocate_to_current_adr();
 			setup_c();
-- 
2.20.1


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             reply	other threads:[~2019-04-15  0:21 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-15  0:21 Andrey Smirnov [this message]
2019-04-15  0:21 ` [PATCH 2/3] ARM: zii-imx51-rdu1: " Andrey Smirnov
2019-04-15  0:21 ` [PATCH 3/3] ARM: zii-imx8mq-dev: Drop unnecessary barrier() in switch statement Andrey Smirnov
2019-04-23  9:33 ` [PATCH 1/3] ARM: zii-vf610-dev: Use -fno-tree-switch-conversion -fno-jump-tables Sascha Hauer

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