From: Allen Martin <amartin@nvidia.com>
To: u-boot@lists.denx.de
Subject: [U-Boot] [PATCH v2 8/9] arm: use thumb interworking returns in libgcc
Date: Wed, 1 Aug 2012 14:55:08 -0700 [thread overview]
Message-ID: <20120801215508.GB1796@nvidia.com> (raw)
In-Reply-To: <CAM=4YET4BGLkJ7UyHd8ritrCQXPR6wa7+9hN8C4Q9dLZ2GbFYA@mail.gmail.com>
On Wed, Aug 01, 2012 at 02:11:48PM -0700, V, Aneesh wrote:
> Hi Allen,
>
> On Wed, Aug 1, 2012 at 1:32 PM, Allen Martin <amartin at nvidia.com<mailto:amartin@nvidia.com>> wrote:
> If CONFIG_SYS_THUMB_BUILD is enabled, use thumb interworking return
> instructions from libgcc routines, otherwise use ARM returns.
>
> Signed-off-by: Allen Martin <amartin at nvidia.com<mailto:amartin@nvidia.com>>
> ---
> arch/arm/include/asm/assembler.h | 10 ++++++++++
> arch/arm/lib/_ashldi3.S | 3 ++-
> arch/arm/lib/_ashrdi3.S | 3 ++-
> arch/arm/lib/_divsi3.S | 15 +++++++++++----
> arch/arm/lib/_lshrdi3.S | 3 ++-
> arch/arm/lib/_modsi3.S | 9 ++++++++-
> arch/arm/lib/_udivsi3.S | 8 +++++---
> arch/arm/lib/_umodsi3.S | 18 +++++++++++++++++-
> arch/arm/lib/memcpy.S | 10 ++++++++++
> arch/arm/lib/memset.S | 3 ++-
> 10 files changed, 69 insertions(+), 13 deletions(-)
>
> diff --git a/arch/arm/include/asm/assembler.h b/arch/arm/include/asm/assembler.h
> index 5e4789b..25ece01 100644
> --- a/arch/arm/include/asm/assembler.h
> +++ b/arch/arm/include/asm/assembler.h
> @@ -13,6 +13,7 @@
> * Do not include any C declarations in this file - it is included by
> * assembler source.
> */
> +#include <config.h>
>
> /*
> * Endian independent macros for shifting bytes within registers.
> @@ -58,3 +59,12 @@
> * Cache alligned
> */
> #define CALGN(code...) code
> +
> +/*
> + * return instruction
> + */
> +#ifdef CONFIG_SYS_THUMB_BUILD
> +#define RET bx lr
> +#else
> +#define RET mov pc, lr
>
> Why not "bx lr" in all cases? In that case you can just replace all the instances of
> "mov pc, lr" directly by "bx lr" instead of this macro. That looks cleaner to me.
I didn't want to break any older ARM architectures that don't support the
bx instruction but use this code.
> BTW, as far as I remember when I did this originally my compiler was compiling
> all assembly functions in ARM and it was automatically converting "mov pc, lr" to
> "bx lr" ,where necessary. Maybe that was just my compiler and I don't remember
> the details now. Did you really face any issue with "mov pc, lr" making wrong jumps?
Yes, without this change if I disassemble the code I'm seeing it's
still a mov instruction and it hangs.
-Allen
--
nvpublic
next prev parent reply other threads:[~2012-08-01 21:55 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-01 20:32 [U-Boot] [PATCH v2 0/9] enable thumb for tegra20 Allen Martin
2012-08-01 20:32 ` [U-Boot] [PATCH v2 1/9] tools, config.mk: add binutils-version Allen Martin
2012-08-01 20:32 ` [U-Boot] [PATCH v2 2/9] arm: work around assembler bug Allen Martin
2012-08-01 20:32 ` [U-Boot] [PATCH v2 3/9] tegra20: remove inline assembly for u32 cast Allen Martin
2012-08-01 20:32 ` [U-Boot] [PATCH v2 4/9] arm: add _thumb1_case_uqi to libgcc Allen Martin
2012-08-13 23:44 ` Stephen Warren
2012-08-14 0:36 ` Allen Martin
2012-08-14 2:39 ` V, Aneesh
2012-08-14 16:02 ` Stephen Warren
2012-08-01 20:32 ` [U-Boot] [PATCH v2 5/9] arm: use thumb compatible return in arm720t Allen Martin
2012-08-01 20:32 ` [U-Boot] [PATCH v2 6/9] arm: change arm720t to armv4t Allen Martin
2012-08-01 20:32 ` [U-Boot] [PATCH v2 7/9] arm720t: add linkage macro for relocate_code Allen Martin
2012-08-01 20:32 ` [U-Boot] [PATCH v2 8/9] arm: use thumb interworking returns in libgcc Allen Martin
2012-08-01 21:11 ` V, Aneesh
2012-08-01 21:55 ` Allen Martin [this message]
2012-08-01 22:15 ` V, Aneesh
2012-08-01 22:28 ` Allen Martin
2012-08-01 20:32 ` [U-Boot] [PATCH v2 9/9] tegra20: enable thumb build Allen Martin
2012-08-13 21:21 ` [U-Boot] [PATCH v2 0/9] enable thumb for tegra20 Stephen Warren
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