Merge tag 'sound-fix-5.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai...

[linux-2.6-microblaze.git] / arch / s390 / kernel / ftrace.c

diff --git a/arch/s390/kernel/ftrace.c b/arch/s390/kernel/ftrace.c
index b388e87..c6ddeb5 100644 (file)
--- a/arch/s390/kernel/ftrace.c
+++ b/arch/s390/kernel/ftrace.c
@@ -22,56 +22,26 @@
 #include "entry.h"
 
 /*
- * The mcount code looks like this:
- *     stg     %r14,8(%r15)            # offset 0
- *     larl    %r1,<&counter>          # offset 6
- *     brasl   %r14,_mcount            # offset 12
- *     lg      %r14,8(%r15)            # offset 18
- * Total length is 24 bytes. Only the first instruction will be patched
- * by ftrace_make_call / ftrace_make_nop.
- * The enabled ftrace code block looks like this:
+ * To generate function prologue either gcc's hotpatch feature (since gcc 4.8)
+ * or a combination of -pg -mrecord-mcount -mnop-mcount -mfentry flags
+ * (since gcc 9 / clang 10) is used.
+ * In both cases the original and also the disabled function prologue contains
+ * only a single six byte instruction and looks like this:
+ * >   brcl    0,0                     # offset 0
+ * To enable ftrace the code gets patched like above and afterwards looks
+ * like this:
  * >   brasl   %r0,ftrace_caller       # offset 0
- *     larl    %r1,<&counter>          # offset 6
- *     brasl   %r14,_mcount            # offset 12
- *     lg      %r14,8(%r15)            # offset 18
+ *
+ * The instruction will be patched by ftrace_make_call / ftrace_make_nop.
  * The ftrace function gets called with a non-standard C function call ABI
  * where r0 contains the return address. It is also expected that the called
  * function only clobbers r0 and r1, but restores r2-r15.
  * For module code we can't directly jump to ftrace caller, but need a
  * trampoline (ftrace_plt), which clobbers also r1.
- * The return point of the ftrace function has offset 24, so execution
- * continues behind the mcount block.
- * The disabled ftrace code block looks like this:
- * >   jg      .+24                    # offset 0
- *     larl    %r1,<&counter>          # offset 6
- *     brasl   %r14,_mcount            # offset 12
- *     lg      %r14,8(%r15)            # offset 18
- * The jg instruction branches to offset 24 to skip as many instructions
- * as possible.
- * In case we use gcc's hotpatch feature the original and also the disabled
- * function prologue contains only a single six byte instruction and looks
- * like this:
- * >   brcl    0,0                     # offset 0
- * To enable ftrace the code gets patched like above and afterwards looks
- * like this:
- * >   brasl   %r0,ftrace_caller       # offset 0
  */
 
 unsigned long ftrace_plt;
 
-static inline void ftrace_generate_orig_insn(struct ftrace_insn *insn)
-{
-#if defined(CC_USING_HOTPATCH) || defined(CC_USING_NOP_MCOUNT)
-       /* brcl 0,0 */
-       insn->opc = 0xc004;
-       insn->disp = 0;
-#else
-       /* stg r14,8(r15) */
-       insn->opc = 0xe3e0;
-       insn->disp = 0xf0080024;
-#endif
-}
-
 int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
                       unsigned long addr)
 {
@@ -85,15 +55,10 @@ int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
 
        if (copy_from_kernel_nofault(&old, (void *) rec->ip, sizeof(old)))
                return -EFAULT;
-       if (addr == MCOUNT_ADDR) {
-               /* Initial code replacement */
-               ftrace_generate_orig_insn(&orig);
-               ftrace_generate_nop_insn(&new);
-       } else {
-               /* Replace ftrace call with a nop. */
-               ftrace_generate_call_insn(&orig, rec->ip);
-               ftrace_generate_nop_insn(&new);
-       }
+       /* Replace ftrace call with a nop. */
+       ftrace_generate_call_insn(&orig, rec->ip);
+       ftrace_generate_nop_insn(&new);
+
        /* Verify that the to be replaced code matches what we expect. */
        if (memcmp(&orig, &old, sizeof(old)))
                return -EINVAL;
@@ -198,17 +163,26 @@ int ftrace_disable_ftrace_graph_caller(void)
 
 #ifdef CONFIG_KPROBES_ON_FTRACE
 void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
-               struct ftrace_ops *ops, struct pt_regs *regs)
+               struct ftrace_ops *ops, struct ftrace_regs *fregs)
 {
        struct kprobe_ctlblk *kcb;
-       struct kprobe *p = get_kprobe((kprobe_opcode_t *)ip);
+       struct pt_regs *regs;
+       struct kprobe *p;
+       int bit;
 
-       if (unlikely(!p) || kprobe_disabled(p))
+       bit = ftrace_test_recursion_trylock(ip, parent_ip);
+       if (bit < 0)
                return;
 
+       regs = ftrace_get_regs(fregs);
+       preempt_disable_notrace();
+       p = get_kprobe((kprobe_opcode_t *)ip);
+       if (unlikely(!p) || kprobe_disabled(p))
+               goto out;
+
        if (kprobe_running()) {
                kprobes_inc_nmissed_count(p);
-               return;
+               goto out;
        }
 
        __this_cpu_write(current_kprobe, p);
@@ -228,6 +202,9 @@ void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
                }
        }
        __this_cpu_write(current_kprobe, NULL);
+out:
+       preempt_enable_notrace();
+       ftrace_test_recursion_unlock(bit);
 }
 NOKPROBE_SYMBOL(kprobe_ftrace_handler);