* [PATCH 1/3] ARM: zii-vf610-dev: Use -fno-tree-switch-conversion -fno-jump-tables
@ 2019-04-15 0:21 Andrey Smirnov
2019-04-15 0:21 ` [PATCH 2/3] ARM: zii-imx51-rdu1: " Andrey Smirnov
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: Andrey Smirnov @ 2019-04-15 0:21 UTC (permalink / raw)
To: barebox; +Cc: Andrey Smirnov, Chris Healy, Heiner Kallweit
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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^ permalink raw reply [flat|nested] 4+ messages in thread* [PATCH 2/3] ARM: zii-imx51-rdu1: Use -fno-tree-switch-conversion -fno-jump-tables
2019-04-15 0:21 [PATCH 1/3] ARM: zii-vf610-dev: Use -fno-tree-switch-conversion -fno-jump-tables Andrey Smirnov
@ 2019-04-15 0:21 ` 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
2 siblings, 0 replies; 4+ messages in thread
From: Andrey Smirnov @ 2019-04-15 0:21 UTC (permalink / raw)
To: barebox; +Cc: Andrey Smirnov, Chris Healy, Heiner Kallweit
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-imx51-rdu1/Makefile | 1 +
arch/arm/boards/zii-imx51-rdu1/lowlevel.c | 7 -------
2 files changed, 1 insertion(+), 7 deletions(-)
diff --git a/arch/arm/boards/zii-imx51-rdu1/Makefile b/arch/arm/boards/zii-imx51-rdu1/Makefile
index 7f2569bda..a17cf5684 100644
--- a/arch/arm/boards/zii-imx51-rdu1/Makefile
+++ b/arch/arm/boards/zii-imx51-rdu1/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-rdu1
diff --git a/arch/arm/boards/zii-imx51-rdu1/lowlevel.c b/arch/arm/boards/zii-imx51-rdu1/lowlevel.c
index 849c5624c..da05b0564 100644
--- a/arch/arm/boards/zii-imx51-rdu1/lowlevel.c
+++ b/arch/arm/boards/zii-imx51-rdu1/lowlevel.c
@@ -84,13 +84,6 @@ ENTRY_FUNCTION(start_imx51_zii_rdu1, r0, r1, r2)
switch (system_type) {
default:
- /*
- * see similar code in
- * arch/arm/boards/zii-vf610-dev/lowlevel.c for
- * reasoning for placing barrier() below.
- */
- barrier();
-
if (IS_ENABLED(CONFIG_DEBUG_LL)) {
relocate_to_current_adr();
setup_c();
--
2.20.1
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^ permalink raw reply [flat|nested] 4+ messages in thread* [PATCH 3/3] ARM: zii-imx8mq-dev: Drop unnecessary barrier() in switch statement
2019-04-15 0:21 [PATCH 1/3] ARM: zii-vf610-dev: Use -fno-tree-switch-conversion -fno-jump-tables Andrey Smirnov
2019-04-15 0:21 ` [PATCH 2/3] ARM: zii-imx51-rdu1: " Andrey Smirnov
@ 2019-04-15 0:21 ` Andrey Smirnov
2019-04-23 9:33 ` [PATCH 1/3] ARM: zii-vf610-dev: Use -fno-tree-switch-conversion -fno-jump-tables Sascha Hauer
2 siblings, 0 replies; 4+ messages in thread
From: Andrey Smirnov @ 2019-04-15 0:21 UTC (permalink / raw)
To: barebox; +Cc: Andrey Smirnov, Chris Healy, Heiner Kallweit
AArch64 uses PC-relative addressing instead of absolute one for data
lookups, so compiling switch statement into a LUT shouldn't be a
problem regardless if relocation happened or not. Disassembly of PBL
code looks almost exactly the same with or without this workaround, so
it is clearly not needed. Drop it.
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-imx8mq-dev/lowlevel.c | 7 -------
1 file changed, 7 deletions(-)
diff --git a/arch/arm/boards/zii-imx8mq-dev/lowlevel.c b/arch/arm/boards/zii-imx8mq-dev/lowlevel.c
index 0fd2ddfca..33c007e05 100644
--- a/arch/arm/boards/zii-imx8mq-dev/lowlevel.c
+++ b/arch/arm/boards/zii-imx8mq-dev/lowlevel.c
@@ -179,13 +179,6 @@ ENTRY_FUNCTION(start_zii_imx8mq_dev, r0, r1, r2)
switch (system_type) {
default:
- /*
- * see similar code in
- * arch/arm/boards/zii-vf610-dev/lowlevel.c for
- * reasoning for placing barrier() below.
- */
- barrier();
-
if (IS_ENABLED(CONFIG_DEBUG_LL)) {
relocate_to_current_adr();
setup_c();
--
2.20.1
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^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH 1/3] ARM: zii-vf610-dev: Use -fno-tree-switch-conversion -fno-jump-tables
2019-04-15 0:21 [PATCH 1/3] ARM: zii-vf610-dev: Use -fno-tree-switch-conversion -fno-jump-tables Andrey Smirnov
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 ` Sascha Hauer
2 siblings, 0 replies; 4+ messages in thread
From: Sascha Hauer @ 2019-04-23 9:33 UTC (permalink / raw)
To: Andrey Smirnov; +Cc: barebox, Chris Healy, Heiner Kallweit
On Sun, Apr 14, 2019 at 05:21:19PM -0700, Andrey Smirnov wrote:
> 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>
Applied, thanks
Sascha
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^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2019-04-23 9:33 UTC | newest]
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2019-04-15 0:21 [PATCH 1/3] ARM: zii-vf610-dev: Use -fno-tree-switch-conversion -fno-jump-tables Andrey Smirnov
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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