@@ -39,11 +39,14 @@ struct mod_arch_specific {
unsigned long tramp;
#endif
-#else
+#else /* powerpc64 */
/* Indices of PLT sections within module. */
unsigned int core_plt_section;
unsigned int init_plt_section;
+#ifdef CONFIG_DYNAMIC_FTRACE
+ unsigned long tramp;
#endif
+#endif /* powerpc64 */
/* List of BUG addresses, source line numbers and filenames */
struct list_head bug_list;
@@ -274,7 +274,63 @@ static int
__ftrace_make_nop(struct module *mod,
struct dyn_ftrace *rec, unsigned long addr)
{
- /* Ignore modules for PPC32 (for now) */
+ unsigned char replaced[MCOUNT_INSN_SIZE];
+ unsigned int *op = (unsigned *)&replaced;
+ unsigned char jmp[8];
+ unsigned int *ptr = (unsigned int *)&jmp;
+ unsigned long ip = rec->ip;
+ unsigned long tramp;
+ int offset;
+
+ if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))
+ return -EFAULT;
+
+ /* Make sure that that this is still a 24bit jump */
+ if (!is_bl_op(*op)) {
+ printk(KERN_ERR "Not expected bl: opcode is %x\n", *op);
+ return -EINVAL;
+ }
+
+ /* lets find where the pointer goes */
+ tramp = find_bl_target(ip, *op);
+
+ /*
+ * On PPC32 the trampoline looks like:
+ * lis r11,sym@ha
+ * addi r11,r11,sym@l
+ * mtctr r11
+ * bctr
+ */
+
+ DEBUGP("ip:%lx jumps to %lx", ip, tramp);
+
+ /* Find where the trampoline jumps to */
+ if (probe_kernel_read(jmp, (void *)tramp, 8)) {
+ printk(KERN_ERR "Failed to read %lx\n", tramp);
+ return -EFAULT;
+ }
+
+ DEBUGP(" %08x %08x ", ptr[0], ptr[1]);
+
+ tramp = (ptr[1] & 0xffff) |
+ ((ptr[0] & 0xffff) << 16);
+ if (tramp & 0x8000)
+ tramp -= 0x10000;
+
+ DEBUGP(" %x ", tramp);
+
+ if (tramp != addr) {
+ printk(KERN_ERR
+ "Trampoline location %08lx does not match addr\n",
+ tramp);
+ return -EINVAL;
+ }
+
+ op[0] = PPC_NOP_INSTR;
+
+ if (probe_kernel_write((void *)ip, replaced, MCOUNT_INSN_SIZE))
+ return -EPERM;
+
return 0;
}
#endif /* PPC64 */
@@ -297,7 +353,6 @@ int ftrace_make_nop(struct module *mod,
return ftrace_modify_code(ip, old, new);
}
-#ifdef CONFIG_PPC64
/*
* Out of range jumps are called from modules.
* We should either already have a pointer to the module
@@ -320,7 +375,6 @@ int ftrace_make_nop(struct module *mod,
/* nothing to do if mod == rec->arch.mod */
} else
mod = rec->arch.mod;
-#endif /* CONFIG_PPC64 */
return __ftrace_make_nop(mod, rec, addr);
@@ -380,7 +434,44 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
static int
__ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
{
- /* PPC32 ignores modules for now */
+ unsigned char replaced[MCOUNT_INSN_SIZE];
+ unsigned int *op = (unsigned *)&replaced;
+ unsigned long ip = rec->ip;
+ unsigned long offset;
+
+ /* read where this goes */
+ if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))
+ return -EFAULT;
+
+ /* It should be pointing to a nop */
+ if (op[0] != PPC_NOP_INSTR) {
+ printk(KERN_ERR "Expected NOP but have %x\n", op[0]);
+ return -EINVAL;
+ }
+
+ /* If we never set up a trampoline to ftrace_caller, then bail */
+ if (!rec->arch.mod->arch.tramp) {
+ printk(KERN_ERR "No ftrace trampoline\n");
+ return -EINVAL;
+ }
+
+ /* now calculate a jump to the ftrace caller trampoline */
+ offset = rec->arch.mod->arch.tramp - ip;
+
+ if (test_offset(offset)) {
+ printk(KERN_ERR "REL24 %li out of range!\n",
+ (long int)offset);
+ return -EINVAL;
+ }
+
+ /* Set to "bl addr" */
+ op[0] = branch_offset(offset);
+
+ DEBUGP("write to %lx\n", rec->ip);
+
+ if (probe_kernel_write((void *)ip, replaced, MCOUNT_INSN_SIZE))
+ return -EPERM;
+
return 0;
}
#endif /* CONFIG_PPC64 */
@@ -402,7 +493,6 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
return ftrace_modify_code(ip, old, new);
}
-#ifdef CONFIG_PPC64
/*
* Out of range jumps are called from modules.
* Being that we are converting from nop, it had better
@@ -412,7 +502,6 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
printk(KERN_ERR "No module loaded\n");
return -EINVAL;
}
-#endif
return __ftrace_make_call(rec, addr);
}
@@ -22,6 +22,7 @@
#include <linux/fs.h>
#include <linux/string.h>
#include <linux/kernel.h>
+#include <linux/ftrace.h>
#include <linux/cache.h>
#include <linux/bug.h>
#include <linux/sort.h>
@@ -53,6 +54,9 @@ static unsigned int count_relocs(const Elf32_Rela *rela, unsigned int num)
r_addend = rela[i].r_addend;
}
+#ifdef CONFIG_DYNAMIC_FTRACE
+ _count_relocs++; /* add one for ftrace_caller */
+#endif
return _count_relocs;
}
@@ -306,5 +310,11 @@ int apply_relocate_add(Elf32_Shdr *sechdrs,
return -ENOEXEC;
}
}
+#ifdef CONFIG_DYNAMIC_FTRACE
+ module->arch.tramp =
+ do_plt_call(module->module_core,
+ (unsigned long)ftrace_caller,
+ sechdrs, module);
+#endif
return 0;
}
Impact: add ability to trace modules on 32 bit PowerPC This patch performs the necessary trampoline calls to handle modules with dynamic ftrace on 32 bit PowerPC. Signed-off-by: Steven Rostedt <srostedt@redhat.com> --- arch/powerpc/include/asm/module.h | 5 ++- arch/powerpc/kernel/ftrace.c | 101 ++++++++++++++++++++++++++++++++++-- arch/powerpc/kernel/module_32.c | 10 ++++ 3 files changed, 109 insertions(+), 7 deletions(-)