On 2022/8/19 16:16, Qing Zhang wrote:
To Implement ftrace trampiones through plt entry.
Tested by forcing ftrace_make_call() to use the module PLT, and then
loading up a module after setting up ftrace with:
| echo ":mod:<module-name>" > set_ftrace_filter;
| echo function > current_tracer;
| modprobe <module-name>
Since FTRACE_ADDR/FTRACE_REGS_ADDR is only defined when CONFIG_DYNAMIC_FTRACE
is selected, we wrap its use along with most of module_init_ftrace_plt() with
ifdeffery rather than using IS_ENABLED().
Signed-off-by: Qing Zhang <zhangqing@xxxxxxxxxxx>
---
arch/loongarch/include/asm/ftrace.h | 4 ++
arch/loongarch/include/asm/inst.h | 2 +
arch/loongarch/include/asm/module.h | 14 +++--
arch/loongarch/include/asm/module.lds.h | 1 +
arch/loongarch/kernel/ftrace_dyn.c | 79 +++++++++++++++++++++++++
arch/loongarch/kernel/inst.c | 12 ++++
arch/loongarch/kernel/module-sections.c | 11 ++++
arch/loongarch/kernel/module.c | 48 +++++++++++++++
8 files changed, 166 insertions(+), 5 deletions(-)
[...]
@@ -36,14 +39,15 @@ Elf_Addr module_emit_plt_entry(struct module *mod, unsigned long val);
static inline struct plt_entry emit_plt_entry(unsigned long val)
{
- u32 lu12iw, lu32id, lu52id, jirl;
+ u32 addu16id, lu32id, lu52id, jirl;
- lu12iw = (lu12iw_op << 25 | (((val >> 12) & 0xfffff) << 5) | LOONGARCH_GPR_T1);
+ addu16id = larch_insn_gen_addu16id(LOONGARCH_GPR_T1, LOONGARCH_GPR_ZERO,
+ ADDR_IMM(val, ADDU16ID));
Hi, Qing,
Why change lu12iw to addu16id? They have same effect here.
lu32id = larch_insn_gen_lu32id(LOONGARCH_GPR_T1, ADDR_IMM(val, LU32ID));
lu52id = larch_insn_gen_lu52id(LOONGARCH_GPR_T1, LOONGARCH_GPR_T1, ADDR_IMM(val, LU52ID));
- jirl = larch_insn_gen_jirl(0, LOONGARCH_GPR_T1, 0, (val & 0xfff));
+ jirl = larch_insn_gen_jirl(0, LOONGARCH_GPR_T1, 0, (val & 0xffff));
- return (struct plt_entry) { lu12iw, lu32id, lu52id, jirl };
+ return (struct plt_entry) { addu16id, lu32id, lu52id, jirl };
}
[...]
+static int module_init_ftrace_plt(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs,
+ struct module *mod)
+{
+#ifdef CONFIG_DYNAMIC_FTRACE
+ const Elf_Shdr *s;
+ struct plt_entry *ftrace_plts;
+
+ s = find_section(hdr, sechdrs, ".ftrace_trampoline");
+ if (!s)
+ return -ENOEXEC;
Return value is not used later, may we do something or drop returning value.
Thanks,
Jinyang
+
+ ftrace_plts = (void *)s->sh_addr;
+
+ ftrace_plts[FTRACE_PLT_IDX] = emit_plt_entry(FTRACE_ADDR);
+
+ if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS))
+ ftrace_plts[FTRACE_REGS_PLT_IDX] = emit_plt_entry(FTRACE_REGS_ADDR);
+
+ mod->arch.ftrace_trampolines = ftrace_plts;
+#endif
+ return 0;
+}
+
+int module_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs, struct module *mod)
+{
+ module_init_ftrace_plt(hdr, sechdrs, mod);
+
+ return 0;
+}
