Commit 7cc45e64 authored by Steven Rostedt's avatar Steven Rostedt

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: default avatarSteven Rostedt <srostedt@redhat.com>
parent f48cb8b4
...@@ -39,11 +39,14 @@ struct mod_arch_specific { ...@@ -39,11 +39,14 @@ struct mod_arch_specific {
unsigned long tramp; unsigned long tramp;
#endif #endif
#else #else /* powerpc64 */
/* Indices of PLT sections within module. */ /* Indices of PLT sections within module. */
unsigned int core_plt_section; unsigned int core_plt_section;
unsigned int init_plt_section; unsigned int init_plt_section;
#ifdef CONFIG_DYNAMIC_FTRACE
unsigned long tramp;
#endif #endif
#endif /* powerpc64 */
/* List of BUG addresses, source line numbers and filenames */ /* List of BUG addresses, source line numbers and filenames */
struct list_head bug_list; struct list_head bug_list;
......
...@@ -274,7 +274,63 @@ static int ...@@ -274,7 +274,63 @@ static int
__ftrace_make_nop(struct module *mod, __ftrace_make_nop(struct module *mod,
struct dyn_ftrace *rec, unsigned long addr) 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; return 0;
} }
#endif /* PPC64 */ #endif /* PPC64 */
...@@ -297,7 +353,6 @@ int ftrace_make_nop(struct module *mod, ...@@ -297,7 +353,6 @@ int ftrace_make_nop(struct module *mod,
return ftrace_modify_code(ip, old, new); return ftrace_modify_code(ip, old, new);
} }
#ifdef CONFIG_PPC64
/* /*
* Out of range jumps are called from modules. * Out of range jumps are called from modules.
* We should either already have a pointer to the module * We should either already have a pointer to the module
...@@ -320,7 +375,6 @@ int ftrace_make_nop(struct module *mod, ...@@ -320,7 +375,6 @@ int ftrace_make_nop(struct module *mod,
/* nothing to do if mod == rec->arch.mod */ /* nothing to do if mod == rec->arch.mod */
} else } else
mod = rec->arch.mod; mod = rec->arch.mod;
#endif /* CONFIG_PPC64 */
return __ftrace_make_nop(mod, rec, addr); return __ftrace_make_nop(mod, rec, addr);
...@@ -380,7 +434,44 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) ...@@ -380,7 +434,44 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
static int static int
__ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) __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; return 0;
} }
#endif /* CONFIG_PPC64 */ #endif /* CONFIG_PPC64 */
...@@ -402,7 +493,6 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) ...@@ -402,7 +493,6 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
return ftrace_modify_code(ip, old, new); return ftrace_modify_code(ip, old, new);
} }
#ifdef CONFIG_PPC64
/* /*
* Out of range jumps are called from modules. * Out of range jumps are called from modules.
* Being that we are converting from nop, it had better * 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) ...@@ -412,7 +502,6 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
printk(KERN_ERR "No module loaded\n"); printk(KERN_ERR "No module loaded\n");
return -EINVAL; return -EINVAL;
} }
#endif
return __ftrace_make_call(rec, addr); return __ftrace_make_call(rec, addr);
} }
......
...@@ -22,6 +22,7 @@ ...@@ -22,6 +22,7 @@
#include <linux/fs.h> #include <linux/fs.h>
#include <linux/string.h> #include <linux/string.h>
#include <linux/kernel.h> #include <linux/kernel.h>
#include <linux/ftrace.h>
#include <linux/cache.h> #include <linux/cache.h>
#include <linux/bug.h> #include <linux/bug.h>
#include <linux/sort.h> #include <linux/sort.h>
...@@ -53,6 +54,9 @@ static unsigned int count_relocs(const Elf32_Rela *rela, unsigned int num) ...@@ -53,6 +54,9 @@ static unsigned int count_relocs(const Elf32_Rela *rela, unsigned int num)
r_addend = rela[i].r_addend; r_addend = rela[i].r_addend;
} }
#ifdef CONFIG_DYNAMIC_FTRACE
_count_relocs++; /* add one for ftrace_caller */
#endif
return _count_relocs; return _count_relocs;
} }
...@@ -306,5 +310,11 @@ int apply_relocate_add(Elf32_Shdr *sechdrs, ...@@ -306,5 +310,11 @@ int apply_relocate_add(Elf32_Shdr *sechdrs,
return -ENOEXEC; return -ENOEXEC;
} }
} }
#ifdef CONFIG_DYNAMIC_FTRACE
module->arch.tramp =
do_plt_call(module->module_core,
(unsigned long)ftrace_caller,
sechdrs, module);
#endif
return 0; return 0;
} }
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