struct dyn_ftrace *rec, unsigned long addr)
{
unsigned int op;
- unsigned int jmp[5];
unsigned long ptr;
unsigned long ip = rec->ip;
- unsigned long tramp;
- int offset;
+ void *tramp;
/* read where this goes */
if (probe_kernel_read(&op, (void *)ip, sizeof(int)))
}
/* lets find where the pointer goes */
- tramp = find_bl_target(ip, op);
-
- /*
- * On PPC64 the trampoline looks like:
- * 0x3d, 0x82, 0x00, 0x00, addis r12,r2, <high>
- * 0x39, 0x8c, 0x00, 0x00, addi r12,r12, <low>
- * Where the bytes 2,3,6 and 7 make up the 32bit offset
- * to the TOC that holds the pointer.
- * to jump to.
- * 0xf8, 0x41, 0x00, 0x28, std r2,40(r1)
- * 0xe9, 0x6c, 0x00, 0x20, ld r11,32(r12)
- * The actually address is 32 bytes from the offset
- * into the TOC.
- * 0xe8, 0x4c, 0x00, 0x28, ld r2,40(r12)
- */
-
- pr_devel("ip:%lx jumps to %lx r2: %lx", ip, tramp, mod->arch.toc);
-
- /* Find where the trampoline jumps to */
- if (probe_kernel_read(jmp, (void *)tramp, sizeof(jmp))) {
- printk(KERN_ERR "Failed to read %lx\n", tramp);
- return -EFAULT;
- }
+ tramp = (void *)find_bl_target(ip, op);
- pr_devel(" %08x %08x", jmp[0], jmp[1]);
+ pr_devel("ip:%lx jumps to %p", ip, tramp);
- /* verify that this is what we expect it to be */
- if (((jmp[0] & 0xffff0000) != 0x3d820000) ||
- ((jmp[1] & 0xffff0000) != 0x398c0000) ||
- (jmp[2] != 0xf8410028) ||
- (jmp[3] != 0xe96c0020) ||
- (jmp[4] != 0xe84c0028)) {
+ if (!is_module_trampoline(tramp)) {
printk(KERN_ERR "Not a trampoline\n");
return -EINVAL;
}
- /* The bottom half is signed extended */
- offset = ((unsigned)((unsigned short)jmp[0]) << 16) +
- (int)((short)jmp[1]);
-
- pr_devel(" %x ", offset);
-
- /* get the address this jumps too */
- tramp = mod->arch.toc + offset + 32;
- pr_devel("toc: %lx", tramp);
-
- if (probe_kernel_read(jmp, (void *)tramp, 8)) {
- printk(KERN_ERR "Failed to read %lx\n", tramp);
+ if (module_trampoline_target(mod, tramp, &ptr)) {
+ printk(KERN_ERR "Failed to get trampoline target\n");
return -EFAULT;
}
- pr_devel(" %08x %08x\n", jmp[0], jmp[1]);
-
-#ifdef __LITTLE_ENDIAN__
- ptr = ((unsigned long)jmp[1] << 32) + jmp[0];
-#else
- ptr = ((unsigned long)jmp[0] << 32) + jmp[1];
-#endif
+ pr_devel("trampoline target %lx", ptr);
/* This should match what was called */
if (ptr != ppc_function_entry((void *)addr)) {
- printk(KERN_ERR "addr does not match %lx\n", ptr);
+ printk(KERN_ERR "addr %lx does not match expected %lx\n",
+ ptr, ppc_function_entry((void *)addr));
return -EINVAL;
}
/*
- * We want to nop the line, but the next line is
- * 0xe8, 0x41, 0x00, 0x28 ld r2,40(r1)
- * This needs to be turned to a nop too.
- */
- if (probe_kernel_read(&op, (void *)(ip+4), MCOUNT_INSN_SIZE))
- return -EFAULT;
-
- if (op != 0xe8410028) {
- printk(KERN_ERR "Next line is not ld! (%08x)\n", op);
- return -EINVAL;
- }
-
- /*
- * Milton Miller pointed out that we can not blindly do nops.
- * If a task was preempted when calling a trace function,
- * the nops will remove the way to restore the TOC in r2
- * and the r2 TOC will get corrupted.
- */
-
- /*
- * Replace:
- * bl <tramp> <==== will be replaced with "b 1f"
- * ld r2,40(r1)
- * 1:
+ * Our original call site looks like:
+ *
+ * bl <tramp>
+ * ld r2,XX(r1)
+ *
+ * Milton Miller pointed out that we can not simply nop the branch.
+ * If a task was preempted when calling a trace function, the nops
+ * will remove the way to restore the TOC in r2 and the r2 TOC will
+ * get corrupted.
+ *
+ * Use a b +8 to jump over the load.
*/
op = 0x48000008; /* b +8 */
__ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
{
unsigned int op[2];
- unsigned long ip = rec->ip;
+ void *ip = (void *)rec->ip;
/* read where this goes */
- if (probe_kernel_read(op, (void *)ip, MCOUNT_INSN_SIZE * 2))
+ if (probe_kernel_read(op, ip, sizeof(op)))
return -EFAULT;
/*
- * It should be pointing to two nops or
- * b +8; ld r2,40(r1)
+ * We expect to see:
+ *
+ * b +8
+ * ld r2,XX(r1)
+ *
+ * The load offset is different depending on the ABI. For simplicity
+ * just mask it out when doing the compare.
*/
- if (((op[0] != 0x48000008) || (op[1] != 0xe8410028)) &&
- ((op[0] != PPC_INST_NOP) || (op[1] != PPC_INST_NOP))) {
- printk(KERN_ERR "Expected NOPs but have %x %x\n", op[0], op[1]);
+ if ((op[0] != 0x48000008) || ((op[1] & 0xffff00000) != 0xe8410000)) {
+ printk(KERN_ERR "Unexpected call sequence: %x %x\n",
+ op[0], op[1]);
return -EINVAL;
}
return -EINVAL;
}
- /* create the branch to the trampoline */
- op[0] = create_branch((unsigned int *)ip,
- rec->arch.mod->arch.tramp, BRANCH_SET_LINK);
- if (!op[0]) {
- printk(KERN_ERR "REL24 out of range!\n");
+ /* Ensure branch is within 24 bits */
+ if (create_branch(ip, rec->arch.mod->arch.tramp, BRANCH_SET_LINK)) {
+ printk(KERN_ERR "Branch out of range");
return -EINVAL;
}
- /* ld r2,40(r1) */
- op[1] = 0xe8410028;
-
- pr_devel("write to %lx\n", rec->ip);
-
- if (probe_kernel_write((void *)ip, op, MCOUNT_INSN_SIZE * 2))
- return -EPERM;
-
- flush_icache_range(ip, ip + 8);
+ if (patch_branch(ip, rec->arch.mod->arch.tramp, BRANCH_SET_LINK)) {
+ printk(KERN_ERR "REL24 out of range!\n");
+ return -EINVAL;
+ }
return 0;
}
projects / karo-tx-linux.git / blobdiff