[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20100331182518.GA30522@debian>
Date: Wed, 31 Mar 2010 23:55:18 +0530
From: Rabin Vincent <rabin@....in>
To: Catalin Marinas <catalin.marinas@....com>
Cc: linux-kernel@...r.kernel.org,
Abhishek Sagar <sagar.abhishek@...il.com>,
Uwe Kleine-König
<u.kleine-koenig@...gutronix.de>,
Steven Rostedt <rostedt@...dmis.org>,
Ingo Molnar <mingo@...hat.com>,
Frederic Weisbecker <fweisbec@...il.com>,
linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 06/10] ARM: ftrace: add Thumb-2 support
On Tue, Mar 16, 2010 at 10:23:54AM +0000, Catalin Marinas wrote:
> If the ftrace_stub isn't .globl, the code compiles fine. My approach
> would be something like this:
New patch below:
>From bf828a0c069b1bb3f6bf4e68f1dceecab396c286 Mon Sep 17 00:00:00 2001
From: Rabin Vincent <rabin@....in>
Date: Sun, 14 Feb 2010 01:18:34 +0530
Subject: [PATCH 06/10] ARM: ftrace: add Thumb-2 support
Fix the mcount routines to build and run on a kernel built with the
Thumb-2 instruction set by correcting the following errors using the
fixes suggested by Catalin Marinas:
- Problem: The following assembler errors appear at the "adr r0,
ftrace_stub" instruction:
entry-common.S: Assembler messages:
entry-common.S:179: Error: invalid immediate for address calculation (value = 0x00000004)
Fix: The errors don't occur with a non-global symbol, so use one.
- Problem: The "mov lr, pc" does not set the lsb when storing the pc in
lr. The called function returns with "bx lr", and the mode changes
to ARM.
Fix: Add a label on the return address and use "adr lr, BSYM(label)".
We don't modify the old mcount because it won't be built when using
Thumb-2.
Cc: Catalin Marinas <catalin.marinas@....com>
Signed-off-by: Rabin Vincent <rabin@....in>
---
arch/arm/kernel/entry-common.S | 6 ++++--
1 files changed, 4 insertions(+), 2 deletions(-)
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index c7a8c20..f5e75de 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -167,7 +167,7 @@ ENTRY(__gnu_mcount_nc)
stmdb sp!, {r0-r3, lr}
ldr r0, =ftrace_trace_function
ldr r2, [r0]
- adr r0, ftrace_stub
+ adr r0, .Lftrace_stub
cmp r0, r2
bne gnu_trace
ldmia sp!, {r0-r3, ip, lr}
@@ -177,8 +177,9 @@ gnu_trace:
ldr r1, [sp, #20] @ lr of instrumented routine
mov r0, lr
sub r0, r0, #MCOUNT_INSN_SIZE
- mov lr, pc
+ adr lr, BSYM(1f)
mov pc, r2
+1:
ldmia sp!, {r0-r3, ip, lr}
mov pc, ip
ENDPROC(__gnu_mcount_nc)
@@ -213,6 +214,7 @@ ENDPROC(mcount)
#endif /* CONFIG_DYNAMIC_FTRACE */
ENTRY(ftrace_stub)
+.Lftrace_stub:
mov pc, lr
ENDPROC(ftrace_stub)
--
1.7.0
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists