diff options
Diffstat (limited to 'arch/mips/kernel/ftrace.c')
| -rw-r--r-- | arch/mips/kernel/ftrace.c | 23 |
1 files changed, 12 insertions, 11 deletions
diff --git a/arch/mips/kernel/ftrace.c b/arch/mips/kernel/ftrace.c index 4b5e1f2bfbce..2625232bfe52 100644 --- a/arch/mips/kernel/ftrace.c +++ b/arch/mips/kernel/ftrace.c @@ -333,20 +333,21 @@ void prepare_ftrace_return(unsigned long *parent_ra_addr, unsigned long self_ra, return; /* - * "parent_ra_addr" is the stack address saved the return address of - * the caller of _mcount. + * "parent_ra_addr" is the stack address where the return address of + * the caller of _mcount is saved. * - * if the gcc < 4.5, a leaf function does not save the return address - * in the stack address, so, we "emulate" one in _mcount's stack space, - * and hijack it directly, but for a non-leaf function, it save the - * return address to the its own stack space, we can not hijack it - * directly, but need to find the real stack address, - * ftrace_get_parent_addr() does it! + * If gcc < 4.5, a leaf function does not save the return address + * in the stack address, so we "emulate" one in _mcount's stack space, + * and hijack it directly. + * For a non-leaf function, it does save the return address to its own + * stack space, so we can not hijack it directly, but need to find the + * real stack address, which is done by ftrace_get_parent_addr(). * - * if gcc>= 4.5, with the new -mmcount-ra-address option, for a + * If gcc >= 4.5, with the new -mmcount-ra-address option, for a * non-leaf function, the location of the return address will be saved - * to $12 for us, and for a leaf function, only put a zero into $12. we - * do it in ftrace_graph_caller of mcount.S. + * to $12 for us. + * For a leaf function, it just puts a zero into $12, so we handle + * it in ftrace_graph_caller() of mcount.S. */ /* old_parent_ra = *parent_ra_addr; */ |