#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
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;
{
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))
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;
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()))) {
}
}
+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 };