Re: [PATCH 09/10] ARM: ftrace: add Thumb-2 support to dynamic ftrace

Steven Rostedt
2010-02-23T13:37:23Z

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") {