powerpc/ppc32: ftrace, dynamic ftrace to handle modules

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>
This commit is contained in:
Steven Rostedt 2008-11-15 02:39:05 -05:00
parent f48cb8b48b
commit 7cc45e6432
3 changed files with 109 additions and 7 deletions

View File

@ -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;

View File

@ -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);
}

View File

@ -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;
}