LoongArch/ftrace: Add HAVE_DYNAMIC_FTRACE_WITH_REGS support

This patch implements CONFIG_DYNAMIC_FTRACE_WITH_REGS on LoongArch,
which allows a traced function's arguments (and some other registers)
to be captured into a struct pt_regs, allowing these to be inspected
and modified.

Co-developed-by: Jinyang He <hejinyang@loongson.cn>
Signed-off-by: Jinyang He <hejinyang@loongson.cn>
Signed-off-by: Qing Zhang <zhangqing@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index 6e9aaa7..f2d1b2a 100644 (file)
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -89,6 +89,7 @@ config LOONGARCH
        select HAVE_DEBUG_STACKOVERFLOW
        select HAVE_DMA_CONTIGUOUS
        select HAVE_DYNAMIC_FTRACE
+       select HAVE_DYNAMIC_FTRACE_WITH_REGS
        select HAVE_EBPF_JIT
        select HAVE_EXIT_THREAD
        select HAVE_FAST_GUP

diff --git a/arch/loongarch/include/asm/ftrace.h b/arch/loongarch/include/asm/ftrace.h
index 09ff0f8..dd4a0c8 100644 (file)
--- a/arch/loongarch/include/asm/ftrace.h
+++ b/arch/loongarch/include/asm/ftrace.h
@@ -23,6 +23,8 @@ extern void prepare_ftrace_return(unsigned long self_addr, unsigned long callsit
 struct dyn_ftrace;
 struct dyn_arch_ftrace { };
 
+#define ARCH_SUPPORTS_FTRACE_OPS 1
+
 #define ftrace_init_nop ftrace_init_nop
 int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec);
 

diff --git a/arch/loongarch/kernel/ftrace_dyn.c b/arch/loongarch/kernel/ftrace_dyn.c
index 5a801c3..d6f3091 100644 (file)
--- a/arch/loongarch/kernel/ftrace_dyn.c
+++ b/arch/loongarch/kernel/ftrace_dyn.c
@@ -28,6 +28,21 @@ static int ftrace_modify_code(unsigned long pc, u32 old, u32 new, bool validate)
        return 0;
 }
 
+#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
+int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, unsigned long addr)
+{
+       u32 old, new;
+       unsigned long pc;
+
+       pc = rec->ip + LOONGARCH_INSN_SIZE;
+
+       new = larch_insn_gen_bl(pc, addr);
+       old = larch_insn_gen_bl(pc, old_addr);
+
+       return ftrace_modify_code(pc, old, new, true);
+}
+#endif /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */
+
 int ftrace_update_ftrace_func(ftrace_func_t func)
 {
        u32 new;

diff --git a/arch/loongarch/kernel/mcount_dyn.S b/arch/loongarch/kernel/mcount_dyn.S
index cce3daa..bbabf06 100644 (file)
--- a/arch/loongarch/kernel/mcount_dyn.S
+++ b/arch/loongarch/kernel/mcount_dyn.S
@@ -27,7 +27,7 @@
  * follows the LoongArch's psABI as well.
  */
 
-       .macro  ftrace_regs_entry
+       .macro  ftrace_regs_entry allregs=0
        PTR_ADDI        sp, sp, -PT_SIZE
        PTR_S           t0, sp, PT_R1  /* Save parent ra at PT_R1(RA) */
        PTR_S           a0, sp, PT_R4
@@ -39,6 +39,30 @@
        PTR_S           a6, sp, PT_R10
        PTR_S           a7, sp, PT_R11
        PTR_S           fp, sp, PT_R22
+       .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
+       PTR_S           t5, sp, PT_R17
+       PTR_S           t6, sp, PT_R18
+       PTR_S           t7, sp, PT_R19
+       PTR_S           t8, sp, PT_R20
+       PTR_S           u0, sp, PT_R21
+       PTR_S           s0, sp, PT_R23
+       PTR_S           s1, sp, PT_R24
+       PTR_S           s2, sp, PT_R25
+       PTR_S           s3, sp, PT_R26
+       PTR_S           s4, sp, PT_R27
+       PTR_S           s5, sp, PT_R28
+       PTR_S           s6, sp, PT_R29
+       PTR_S           s7, sp, PT_R30
+       PTR_S           s8, sp, PT_R31
+       /* Clear it for later use as a flag sometimes. */
+       PTR_S           zero, sp, PT_R0
+       .endif
        PTR_S           ra, sp, PT_ERA /* Save trace function ra at PT_ERA */
        PTR_ADDI        t8, sp, PT_SIZE
        PTR_S           t8, sp, PT_R3
@@ -85,10 +109,17 @@ ftrace_common_return:
 SYM_CODE_END(ftrace_common)
 
 SYM_CODE_START(ftrace_caller)
-       ftrace_regs_entry
+       ftrace_regs_entry allregs=0
        b               ftrace_common
 SYM_CODE_END(ftrace_caller)
 
+#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
+SYM_CODE_START(ftrace_regs_caller)
+       ftrace_regs_entry allregs=1
+       b               ftrace_common
+SYM_CODE_END(ftrace_regs_caller)
+#endif
+
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 SYM_CODE_START(ftrace_graph_caller)
        PTR_L           a0, sp, PT_ERA