@@ -95,6 +95,7 @@ config LOONGARCH
select HAVE_DMA_CONTIGUOUS
select HAVE_DYNAMIC_FTRACE
select HAVE_DYNAMIC_FTRACE_WITH_ARGS
+ select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
select HAVE_DYNAMIC_FTRACE_WITH_REGS
select HAVE_EBPF_JIT
select HAVE_EFFICIENT_UNALIGNED_ACCESS if !ARCH_STRICT_ALIGN
@@ -57,6 +57,18 @@ static __always_inline struct pt_regs *arch_ftrace_get_regs(struct ftrace_regs *
#define ftrace_graph_func ftrace_graph_func
void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
struct ftrace_ops *op, struct ftrace_regs *fregs);
+
+#ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
+static inline void
+__arch_ftrace_set_direct_caller(struct pt_regs *regs, unsigned long addr)
+{
+ regs->regs[13] = addr; /* t1 */
+}
+
+#define arch_ftrace_set_direct_caller(fregs, addr) \
+ __arch_ftrace_set_direct_caller(&(fregs)->regs, addr)
+#endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */
+
#endif
#endif /* __ASSEMBLY__ */
@@ -66,6 +66,14 @@ static bool ftrace_find_callable_addr(struct dyn_ftrace *rec, struct module *mod
unsigned long pc = rec->ip + LOONGARCH_INSN_SIZE;
struct plt_entry *plt;
+ /*
+ * If a custom trampoline is unreachable, rely on the ftrace_regs_caller
+ * trampoline which knows how to indirectly reach that trampoline
+ * through ops->direct_call.
+ */
+ if (*addr != FTRACE_ADDR && *addr != FTRACE_REGS_ADDR && !reachable_by_bl(*addr, pc))
+ *addr = FTRACE_REGS_ADDR;
+
/*
* When the target is within range of the 'bl' instruction, use 'addr'
* as-is and branch to that directly.
@@ -42,7 +42,6 @@
.if \allregs
PTR_S tp, sp, PT_R2
PTR_S t0, sp, PT_R12
- PTR_S t1, sp, PT_R13
PTR_S t2, sp, PT_R14
PTR_S t3, sp, PT_R15
PTR_S t4, sp, PT_R16
@@ -64,6 +63,8 @@
PTR_S zero, sp, PT_R0
.endif
PTR_S ra, sp, PT_ERA /* Save trace function ra at PT_ERA */
+ move t1, zero
+ PTR_S t1, sp, PT_R13
PTR_ADDI t8, sp, PT_SIZE
PTR_S t8, sp, PT_R3
.endm
@@ -104,8 +105,12 @@ ftrace_common_return:
PTR_L a7, sp, PT_R11
PTR_L fp, sp, PT_R22
PTR_L t0, sp, PT_ERA
+ PTR_L t1, sp, PT_R13
PTR_ADDI sp, sp, PT_SIZE
+ bnez t1,.Ldirect
jr t0
+.Ldirect:
+ jr t1
SYM_CODE_END(ftrace_common)
SYM_CODE_START(ftrace_caller)
Select the DYNAMIC_FTRACE_WITH_DIRECT_CALLS to provide the register_ftrace_direct[_multi] interfaces allowing users to register the customed trampoline (direct_caller) as the mcount for one or more target functions. And modify_ftrace_direct[_multi] are also provided for modifying direct_caller. There are a few cases to distinguish: - If a direct call ops is the only one tracing a function AND the direct called trampoline is within the reach of a 'bl' instruction -> the ftrace patchsite jumps to the trampoline - Else -> the ftrace patchsite jumps to the ftrace_regs_caller trampoline points to ftrace_list_ops so it iterates over all registered ftrace ops, including the direct call ops and calls its call_direct_funcs handler which stores the direct called trampoline's address in the ftrace_regs and the ftrace_regs_caller trampoline will return to that address instead of returning to the traced function Signed-off-by: Qing Zhang <zhangqing@loongson.cn> Signed-off-by: Youling Tang <tangyouling@loongson.cn> --- arch/loongarch/Kconfig | 1 + arch/loongarch/include/asm/ftrace.h | 12 ++++++++++++ arch/loongarch/kernel/ftrace_dyn.c | 8 ++++++++ arch/loongarch/kernel/mcount_dyn.S | 7 ++++++- 4 files changed, 27 insertions(+), 1 deletion(-)