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    SubjectRe: [PATCH 09/10] ARM: ftrace: add Thumb-2 support to dynamic ftrace
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    On Sun, 2010-02-14 at 01:18 +0530, Rabin Vincent wrote:
    > Handle the different nop and call instructions for Thumb-2. Also, we
    > need to adjust the recorded mcount_loc addresses because they have the
    > lsb set.
    >
    > Cc: Catalin Marinas <catalin.marinas@arm.com>
    > Signed-off-by: Rabin Vincent <rabin@rab.in>
    > ---
    > arch/arm/include/asm/ftrace.h | 4 ++++
    > arch/arm/kernel/ftrace.c | 33 +++++++++++++++++++++++++++++++++
    > scripts/recordmcount.pl | 2 +-
    > 3 files changed, 38 insertions(+), 1 deletions(-)
    >
    > diff --git a/arch/arm/include/asm/ftrace.h b/arch/arm/include/asm/ftrace.h
    > index 4a56a2e..0845f2d 100644
    > --- a/arch/arm/include/asm/ftrace.h
    > +++ b/arch/arm/include/asm/ftrace.h
    > @@ -18,7 +18,11 @@ struct dyn_arch_ftrace {
    >
    > static inline unsigned long ftrace_call_adjust(unsigned long addr)
    > {
    > +#ifdef CONFIG_THUMB2_KERNEL
    > + return addr & ~1;

    Would it be safe to do that for all arm archs? Instead of adding a
    config option around it. Or do some arm archs need the lsb set.

    I'm just saying a comment here would look better than #ifdef #else.

    > +#else
    > return addr;
    > +#endif
    > }
    >
    > extern void ftrace_caller_old(void);
    > diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c
    > index f09014c..971ac8c 100644
    > --- a/arch/arm/kernel/ftrace.c
    > +++ b/arch/arm/kernel/ftrace.c
    > @@ -18,7 +18,11 @@
    > #include <asm/cacheflush.h>
    > #include <asm/ftrace.h>
    >
    > +#ifdef CONFIG_THUMB2_KERNEL
    > +#define NOP 0xeb04f85d /* pop.w {lr} */
    > +#else
    > #define NOP 0xe8bd4000 /* pop {lr} */
    > +#endif
    >
    > #ifdef CONFIG_OLD_MCOUNT
    > #define OLD_MCOUNT_ADDR ((unsigned long) mcount)
    > @@ -56,6 +60,34 @@ static unsigned long adjust_address(struct dyn_ftrace *rec, unsigned long addr)
    > #endif
    >
    > /* construct a branch (BL) instruction to addr */
    > +#ifdef CONFIG_THUMB2_KERNEL
    > +static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr)
    > +{
    > + unsigned long s, j1, j2, i1, i2, imm10, imm11;
    > + unsigned long first, second;
    > + long offset;
    > +
    > + offset = (long)addr - (long)(pc + 4);
    > + if (offset < -16777216 || offset > 16777214) {
    > + WARN_ON_ONCE(1);
    > + return 0;
    > + }
    > +
    > + s = (offset >> 24) & 0x1;
    > + i1 = (offset >> 23) & 0x1;
    > + i2 = (offset >> 22) & 0x1;
    > + imm10 = (offset >> 12) & 0x3ff;
    > + imm11 = (offset >> 1) & 0x7ff;
    > +
    > + j1 = (!i1) ^ s;
    > + j2 = (!i2) ^ s;
    > +
    > + first = 0xf000 | (s << 10) | imm10;
    > + second = 0xd000 | (j1 << 13) | (j2 << 11) | imm11;
    > +
    > + return (second << 16) | first;
    > +}
    > +#else
    > static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr)
    > {
    > long offset;
    > @@ -73,6 +105,7 @@ static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr)
    >
    > return 0xeb000000 | offset;
    > }
    > +#endif
    >
    > static int ftrace_modify_code(unsigned long pc, unsigned long old,
    > unsigned long new)
    > diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl
    > index 66c1c4b..88b083b 100755
    > --- a/scripts/recordmcount.pl
    > +++ b/scripts/recordmcount.pl

    For the recordmcount.pl change;

    Acked-by: Steven Rostedt <rostedt@goodmis.org>

    -- Steve

    > @@ -267,7 +267,7 @@ if ($arch eq "x86_64") {
    > } elsif ($arch eq "arm") {
    > $alignment = 2;
    > $section_type = '%progbits';
    > - $mcount_regex = "^\\s*([0-9a-fA-F]+):\\s*R_ARM_(CALL|PC24)" .
    > + $mcount_regex = "^\\s*([0-9a-fA-F]+):\\s*R_ARM_(CALL|PC24|THM_CALL)" .
    > "\\s+(__gnu_mcount_nc|mcount)\$";
    >
    > } elsif ($arch eq "ia64") {



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