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    Subject[PATCH 09/10] ARM: ftrace: add Thumb-2 support to dynamic ftrace
    Date
    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;
    +#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
    @@ -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") {
    --
    1.6.6


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