ARM: ftrace: add Thumb-2 support
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From: Rabin Vincent on 31 Mar 2010 14:30 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(a)rab.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(a)arm.com> Signed-off-by: Rabin Vincent <rabin(a)rab.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(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Catalin Marinas on 23 Apr 2010 11:40
On Wed, 2010-03-31 at 19:25 +0100, Rabin Vincent wrote: > From bf828a0c069b1bb3f6bf4e68f1dceecab396c286 Mon Sep 17 00:00:00 2001 > From: Rabin Vincent <rabin(a)rab.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(a)arm.com> > Signed-off-by: Rabin Vincent <rabin(a)rab.in> Acked-by: Catalin Marinas <catalin.marinas(a)arm.com> -- Catalin -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |