module_trampoline_target() is used by __ftrace_modify_call().
Implement it for PPC32 so that CONFIG_DYNAMIC_FTRACE_WITH_REGS
can be activated on PPC32 as well.
Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
---
arch/powerpc/kernel/module_32.c | 25 ++++++++++++++++++++
arch/powerpc/kernel/trace/ftrace.c | 37 ++++--------------------------
2 files changed, 29 insertions(+), 33 deletions(-)
diff --git a/arch/powerpc/kernel/module_32.c b/arch/powerpc/kernel/module_32.c
index f417afc08d33..5dedd76346b2 100644
--- a/arch/powerpc/kernel/module_32.c
+++ b/arch/powerpc/kernel/module_32.c
@@ -273,6 +273,31 @@ int apply_relocate_add(Elf32_Shdr *sechdrs,
}
#ifdef CONFIG_DYNAMIC_FTRACE
+int module_trampoline_target(struct module *mod, unsigned long addr,
+ unsigned long *target)
+{
+ unsigned int jmp[4];
+
+ /* Find where the trampoline jumps to */
+ if (copy_from_kernel_nofault(jmp, (void *)addr, sizeof(jmp)))
+ return -EFAULT;
+
+ /* verify that this is what we expect it to be */
+ if ((jmp[0] & 0xffff0000) != PPC_RAW_LIS(_R12, 0) ||
+ (jmp[1] & 0xffff0000) != PPC_RAW_ADDI(_R12, _R12, 0) ||
+ jmp[2] != PPC_RAW_MTCTR(_R12) ||
+ jmp[3] != PPC_RAW_BCTR())
+ return -EINVAL;
+
+ addr = (jmp[1] & 0xffff) | ((jmp[0] & 0xffff) << 16);
+ if (addr & 0x8000)
+ addr -= 0x10000;
+
+ *target = addr;
+
+ return 0;
+}
+
int module_finalize_ftrace(struct module *module, const Elf_Shdr *sechdrs)
{
module->arch.tramp = do_plt_call(module->core_layout.base,
diff --git a/arch/powerpc/kernel/trace/ftrace.c b/arch/powerpc/kernel/trace/ftrace.c
index d89c5df4f206..c1d54c18e912 100644
--- a/arch/powerpc/kernel/trace/ftrace.c
+++ b/arch/powerpc/kernel/trace/ftrace.c
@@ -222,9 +222,8 @@ __ftrace_make_nop(struct module *mod,
struct dyn_ftrace *rec, unsigned long addr)
{
struct ppc_inst op;
- unsigned int jmp[4];
unsigned long ip = rec->ip;
- unsigned long tramp;
+ unsigned long tramp, ptr;
if (copy_from_kernel_nofault(&op, (void *)ip, MCOUNT_INSN_SIZE))
return -EFAULT;
@@ -238,41 +237,13 @@ __ftrace_make_nop(struct module *mod,
/* lets find where the pointer goes */
tramp = find_bl_target(ip, op);
- /*
- * On PPC32 the trampoline looks like:
- * 0x3d, 0x80, 0x00, 0x00 lis r12,sym@ha
- * 0x39, 0x8c, 0x00, 0x00 addi r12,r12,sym@l
- * 0x7d, 0x89, 0x03, 0xa6 mtctr r12
- * 0x4e, 0x80, 0x04, 0x20 bctr
- */
-
- pr_devel("ip:%lx jumps to %lx", ip, tramp);
-
/* Find where the trampoline jumps to */
- if (copy_from_kernel_nofault(jmp, (void *)tramp, sizeof(jmp))) {
- pr_err("Failed to read %lx\n", tramp);
+ if (module_trampoline_target(mod, tramp, &ptr)) {
+ pr_err("Failed to get trampoline target\n");
return -EFAULT;
}
- pr_devel(" %08x %08x ", jmp[0], jmp[1]);
-
- /* verify that this is what we expect it to be */
- if (((jmp[0] & 0xffff0000) != 0x3d800000) ||
- ((jmp[1] & 0xffff0000) != 0x398c0000) ||
- (jmp[2] != 0x7d8903a6) ||
- (jmp[3] != 0x4e800420)) {
- pr_err("Not a trampoline\n");
- return -EINVAL;
- }
-
- tramp = (jmp[1] & 0xffff) |
- ((jmp[0] & 0xffff) << 16);
- if (tramp & 0x8000)
- tramp -= 0x10000;
-
- pr_devel(" %lx ", tramp);
-
- if (tramp != addr) {
+ if (ptr != addr) {
pr_err("Trampoline location %08lx does not match addr\n",
tramp);
return -EINVAL;
--
2.31.1
