diff options
| -rw-r--r-- | arch/powerpc/kernel/trace/ftrace.c | 110 |
1 files changed, 17 insertions, 93 deletions
diff --git a/arch/powerpc/kernel/trace/ftrace.c b/arch/powerpc/kernel/trace/ftrace.c index ef4e49c2c377..278bf8e52b6e 100644 --- a/arch/powerpc/kernel/trace/ftrace.c +++ b/arch/powerpc/kernel/trace/ftrace.c @@ -28,13 +28,7 @@ #include <asm/syscall.h> #include <asm/inst.h> -/* - * We generally only have a single long_branch tramp and at most 2 or 3 plt - * tramps generated. But, we don't use the plt tramps currently. We also allot - * 2 tramps after .text and .init.text. So, we only end up with around 3 usable - * tramps in total. Set aside 8 just to be sure. - */ -#define NUM_FTRACE_TRAMPS 8 +#define NUM_FTRACE_TRAMPS 2 static unsigned long ftrace_tramps[NUM_FTRACE_TRAMPS]; static ppc_inst_t @@ -100,11 +94,6 @@ static int is_bl_op(ppc_inst_t op) return (ppc_inst_val(op) & ~PPC_LI_MASK) == PPC_RAW_BL(0); } -static int is_b_op(ppc_inst_t op) -{ - return (ppc_inst_val(op) & ~PPC_LI_MASK) == PPC_RAW_BRANCH(0); -} - static unsigned long find_bl_target(unsigned long ip, ppc_inst_t op) { int offset; @@ -227,11 +216,7 @@ static unsigned long find_ftrace_tramp(unsigned long ip) { int i; - /* - * We have the compiler generated long_branch tramps at the end - * and we prefer those - */ - for (i = NUM_FTRACE_TRAMPS - 1; i >= 0; i--) + for (i = 0; i < NUM_FTRACE_TRAMPS; i++) if (!ftrace_tramps[i]) continue; else if (is_offset_in_branch_range(ftrace_tramps[i] - ip)) @@ -240,75 +225,6 @@ static unsigned long find_ftrace_tramp(unsigned long ip) return 0; } -static int add_ftrace_tramp(unsigned long tramp) -{ - int i; - - for (i = 0; i < NUM_FTRACE_TRAMPS; i++) - if (!ftrace_tramps[i]) { - ftrace_tramps[i] = tramp; - return 0; - } - - return -1; -} - -/* - * If this is a compiler generated long_branch trampoline (essentially, a - * trampoline that has a branch to _mcount()), we re-write the branch to - * instead go to ftrace_[regs_]caller() and note down the location of this - * trampoline. - */ -static int setup_mcount_compiler_tramp(unsigned long tramp) -{ - int i; - ppc_inst_t op; - unsigned long ptr; - - /* Is this a known long jump tramp? */ - for (i = 0; i < NUM_FTRACE_TRAMPS; i++) - if (ftrace_tramps[i] == tramp) - return 0; - - /* New trampoline -- read where this goes */ - if (copy_inst_from_kernel_nofault(&op, (void *)tramp)) { - pr_debug("Fetching opcode failed.\n"); - return -1; - } - - /* Is this a 24 bit branch? */ - if (!is_b_op(op)) { - pr_debug("Trampoline is not a long branch tramp.\n"); - return -1; - } - - /* lets find where the pointer goes */ - ptr = find_bl_target(tramp, op); - - if (ptr != ppc_global_function_entry((void *)_mcount)) { - pr_debug("Trampoline target %p is not _mcount\n", (void *)ptr); - return -1; - } - - /* Let's re-write the tramp to go to ftrace_[regs_]caller */ - if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS)) - ptr = ppc_global_function_entry((void *)ftrace_regs_caller); - else - ptr = ppc_global_function_entry((void *)ftrace_caller); - - if (patch_branch((u32 *)tramp, ptr, 0)) { - pr_debug("REL24 out of range!\n"); - return -1; - } - - if (add_ftrace_tramp(tramp)) { - pr_debug("No tramp locations left\n"); - return -1; - } - - return 0; -} - static int __ftrace_make_nop_kernel(struct dyn_ftrace *rec, unsigned long addr) { unsigned long tramp, ip = rec->ip; @@ -331,13 +247,10 @@ static int __ftrace_make_nop_kernel(struct dyn_ftrace *rec, unsigned long addr) pr_devel("ip:%lx jumps to %lx", ip, tramp); - if (setup_mcount_compiler_tramp(tramp)) { - /* Are other trampolines reachable? */ - if (!find_ftrace_tramp(ip)) { - pr_err("No ftrace trampolines reachable from %ps\n", - (void *)ip); - return -EINVAL; - } + /* Are ftrace trampolines reachable? */ + if (!find_ftrace_tramp(ip)) { + pr_err("No ftrace trampolines reachable from %ps\n", (void *)ip); + return -EINVAL; } if (patch_instruction((u32 *)ip, ppc_inst(PPC_RAW_NOP()))) { @@ -725,6 +638,17 @@ void ftrace_free_init_tramp(void) } } +static void __init add_ftrace_tramp(unsigned long tramp) +{ + int i; + + for (i = 0; i < NUM_FTRACE_TRAMPS; i++) + if (!ftrace_tramps[i]) { + ftrace_tramps[i] = tramp; + return; + } +} + int __init ftrace_dyn_arch_init(void) { unsigned int *tramp[] = { ftrace_tramp_text, ftrace_tramp_init }; |