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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:
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f48cb8b48b
commit
7cc45e6432
3 changed files with 109 additions and 7 deletions
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@ -39,11 +39,14 @@ struct mod_arch_specific {
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unsigned long tramp;
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#endif
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#else
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#else /* powerpc64 */
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/* Indices of PLT sections within module. */
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unsigned int core_plt_section;
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unsigned int init_plt_section;
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#ifdef CONFIG_DYNAMIC_FTRACE
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unsigned long tramp;
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#endif
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#endif /* powerpc64 */
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/* List of BUG addresses, source line numbers and filenames */
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struct list_head bug_list;
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@ -274,7 +274,63 @@ static int
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__ftrace_make_nop(struct module *mod,
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struct dyn_ftrace *rec, unsigned long addr)
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{
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/* Ignore modules for PPC32 (for now) */
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unsigned char replaced[MCOUNT_INSN_SIZE];
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unsigned int *op = (unsigned *)&replaced;
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unsigned char jmp[8];
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unsigned int *ptr = (unsigned int *)&jmp;
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unsigned long ip = rec->ip;
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unsigned long tramp;
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int offset;
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if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))
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return -EFAULT;
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/* Make sure that that this is still a 24bit jump */
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if (!is_bl_op(*op)) {
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printk(KERN_ERR "Not expected bl: opcode is %x\n", *op);
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return -EINVAL;
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}
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/* lets find where the pointer goes */
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tramp = find_bl_target(ip, *op);
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/*
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* On PPC32 the trampoline looks like:
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* lis r11,sym@ha
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* addi r11,r11,sym@l
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* mtctr r11
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* bctr
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*/
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DEBUGP("ip:%lx jumps to %lx", ip, tramp);
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/* Find where the trampoline jumps to */
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if (probe_kernel_read(jmp, (void *)tramp, 8)) {
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printk(KERN_ERR "Failed to read %lx\n", tramp);
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return -EFAULT;
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}
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DEBUGP(" %08x %08x ", ptr[0], ptr[1]);
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tramp = (ptr[1] & 0xffff) |
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((ptr[0] & 0xffff) << 16);
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if (tramp & 0x8000)
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tramp -= 0x10000;
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DEBUGP(" %x ", tramp);
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if (tramp != addr) {
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printk(KERN_ERR
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"Trampoline location %08lx does not match addr\n",
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tramp);
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return -EINVAL;
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}
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op[0] = PPC_NOP_INSTR;
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if (probe_kernel_write((void *)ip, replaced, MCOUNT_INSN_SIZE))
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return -EPERM;
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return 0;
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}
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#endif /* PPC64 */
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@ -297,7 +353,6 @@ int ftrace_make_nop(struct module *mod,
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return ftrace_modify_code(ip, old, new);
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}
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#ifdef CONFIG_PPC64
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/*
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* Out of range jumps are called from modules.
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* We should either already have a pointer to the module
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@ -320,7 +375,6 @@ int ftrace_make_nop(struct module *mod,
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/* nothing to do if mod == rec->arch.mod */
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} else
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mod = rec->arch.mod;
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#endif /* CONFIG_PPC64 */
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return __ftrace_make_nop(mod, rec, addr);
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@ -380,7 +434,44 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
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static int
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__ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
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{
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/* PPC32 ignores modules for now */
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unsigned char replaced[MCOUNT_INSN_SIZE];
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unsigned int *op = (unsigned *)&replaced;
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unsigned long ip = rec->ip;
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unsigned long offset;
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/* read where this goes */
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if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))
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return -EFAULT;
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/* It should be pointing to a nop */
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if (op[0] != PPC_NOP_INSTR) {
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printk(KERN_ERR "Expected NOP but have %x\n", op[0]);
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return -EINVAL;
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}
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/* If we never set up a trampoline to ftrace_caller, then bail */
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if (!rec->arch.mod->arch.tramp) {
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printk(KERN_ERR "No ftrace trampoline\n");
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return -EINVAL;
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}
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/* now calculate a jump to the ftrace caller trampoline */
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offset = rec->arch.mod->arch.tramp - ip;
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if (test_offset(offset)) {
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printk(KERN_ERR "REL24 %li out of range!\n",
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(long int)offset);
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return -EINVAL;
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}
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/* Set to "bl addr" */
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op[0] = branch_offset(offset);
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DEBUGP("write to %lx\n", rec->ip);
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if (probe_kernel_write((void *)ip, replaced, MCOUNT_INSN_SIZE))
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return -EPERM;
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return 0;
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}
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#endif /* CONFIG_PPC64 */
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@ -402,7 +493,6 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
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return ftrace_modify_code(ip, old, new);
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}
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#ifdef CONFIG_PPC64
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/*
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* Out of range jumps are called from modules.
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* Being that we are converting from nop, it had better
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@ -412,7 +502,6 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
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printk(KERN_ERR "No module loaded\n");
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return -EINVAL;
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}
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#endif
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return __ftrace_make_call(rec, addr);
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}
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@ -22,6 +22,7 @@
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#include <linux/fs.h>
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#include <linux/string.h>
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#include <linux/kernel.h>
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#include <linux/ftrace.h>
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#include <linux/cache.h>
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#include <linux/bug.h>
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#include <linux/sort.h>
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@ -53,6 +54,9 @@ static unsigned int count_relocs(const Elf32_Rela *rela, unsigned int num)
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r_addend = rela[i].r_addend;
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}
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#ifdef CONFIG_DYNAMIC_FTRACE
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_count_relocs++; /* add one for ftrace_caller */
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#endif
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return _count_relocs;
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}
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@ -306,5 +310,11 @@ int apply_relocate_add(Elf32_Shdr *sechdrs,
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return -ENOEXEC;
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}
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}
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#ifdef CONFIG_DYNAMIC_FTRACE
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module->arch.tramp =
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do_plt_call(module->module_core,
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(unsigned long)ftrace_caller,
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sechdrs, module);
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#endif
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return 0;
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}
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