#ifndef _ASM_S390_FTRACE_H
#define _ASM_S390_FTRACE_H
+#define HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
#define ARCH_SUPPORTS_FTRACE_OPS 1
-
-#if defined(CC_USING_HOTPATCH) || defined(CC_USING_NOP_MCOUNT)
#define MCOUNT_INSN_SIZE 6
-#else
-#define MCOUNT_INSN_SIZE 24
-#define MCOUNT_RETURN_FIXUP 18
-#endif
-
-#define HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
#ifndef __ASSEMBLY__
#define ftrace_return_address(n) __builtin_return_address(n)
#endif
-void _mcount(void);
void ftrace_caller(void);
extern char ftrace_graph_caller_end;
struct dyn_arch_ftrace { };
-#define MCOUNT_ADDR ((unsigned long)_mcount)
+#define MCOUNT_ADDR 0
#define FTRACE_ADDR ((unsigned long)ftrace_caller)
#define KPROBE_ON_FTRACE_NOP 0
#define KPROBE_ON_FTRACE_CALL 1
+struct module;
+struct dyn_ftrace;
+/*
+ * Either -mhotpatch or -mnop-mcount is used - no explicit init is required
+ */
+static inline int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec) { return 0; }
+#define ftrace_init_nop ftrace_init_nop
+
static inline unsigned long ftrace_call_adjust(unsigned long addr)
{
return addr;
static inline void ftrace_generate_nop_insn(struct ftrace_insn *insn)
{
#ifdef CONFIG_FUNCTION_TRACER
-#if defined(CC_USING_HOTPATCH) || defined(CC_USING_NOP_MCOUNT)
/* brcl 0,0 */
insn->opc = 0xc004;
insn->disp = 0;
-#else
- /* jg .+24 */
- insn->opc = 0xc0f4;
- insn->disp = MCOUNT_INSN_SIZE / 2;
-#endif
#endif
}
static inline int is_ftrace_nop(struct ftrace_insn *insn)
{
#ifdef CONFIG_FUNCTION_TRACER
-#if defined(CC_USING_HOTPATCH) || defined(CC_USING_NOP_MCOUNT)
if (insn->disp == 0)
return 1;
-#else
- if (insn->disp == MCOUNT_INSN_SIZE / 2)
- return 1;
-#endif
#endif
return 0;
}
#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)
{
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;
projects / linux-2.6-block.git / commitdiff