This patch implements ftrace trampolines 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 their usage in module_init_ftrace_plt() with
ifdeffery rather than using IS_ENABLED().
Signed-off-by: Qing Zhang <zhangqing@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
#ifndef _ASM_LOONGARCH_FTRACE_H
#define _ASM_LOONGARCH_FTRACE_H
+#define FTRACE_PLT_IDX 0
+#define FTRACE_REGS_PLT_IDX 1
+#define NR_FTRACE_PLTS 2
+
#define GRAPH_FAKE_OFFSET (sizeof(struct pt_regs) - offsetof(struct pt_regs, regs[1]))
#ifdef CONFIG_FUNCTION_TRACER
#define ADDR_IMMMASK_LU52ID 0xFFF0000000000000
#define ADDR_IMMMASK_LU32ID 0x000FFFFF00000000
+#define ADDR_IMMMASK_LU12IW 0x00000000FFFFF000
#define ADDR_IMMMASK_ADDU16ID 0x00000000FFFF0000
#define ADDR_IMMSHIFT_LU52ID 52
#define ADDR_IMMSHIFT_LU32ID 32
+#define ADDR_IMMSHIFT_LU12IW 12
#define ADDR_IMMSHIFT_ADDU16ID 16
#define ADDR_IMM(addr, INSN) ((addr & ADDR_IMMMASK_##INSN) >> ADDR_IMMSHIFT_##INSN)
u32 larch_insn_gen_or(enum loongarch_gpr rd, enum loongarch_gpr rj, enum loongarch_gpr rk);
u32 larch_insn_gen_move(enum loongarch_gpr rd, enum loongarch_gpr rj);
+u32 larch_insn_gen_lu12iw(enum loongarch_gpr rd, int imm);
u32 larch_insn_gen_lu32id(enum loongarch_gpr rd, int imm);
u32 larch_insn_gen_lu52id(enum loongarch_gpr rd, enum loongarch_gpr rj, int imm);
u32 larch_insn_gen_jirl(enum loongarch_gpr rd, enum loongarch_gpr rj, unsigned long pc, unsigned long dest);
struct mod_section got;
struct mod_section plt;
struct mod_section plt_idx;
+
+ /* For CONFIG_DYNAMIC_FTRACE */
+ struct plt_entry *ftrace_trampolines;
};
struct got_entry {
{
u32 lu12iw, lu32id, lu52id, jirl;
- lu12iw = (lu12iw_op << 25 | (((val >> 12) & 0xfffff) << 5) | LOONGARCH_GPR_T1);
+ lu12iw = larch_insn_gen_lu12iw(LOONGARCH_GPR_T1, ADDR_IMM(val, LU12IW));
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));
.got : { BYTE(0) }
.plt : { BYTE(0) }
.plt.idx : { BYTE(0) }
+ .ftrace_trampoline : { BYTE(0) }
}
#include <linux/uaccess.h>
#include <asm/inst.h>
+#include <asm/module.h>
static int ftrace_modify_code(unsigned long pc, u32 old, u32 new, bool validate)
{
}
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
+
+#ifdef CONFIG_MODULES
+static inline int __get_mod(struct module **mod, unsigned long addr)
+{
+ preempt_disable();
+ *mod = __module_text_address(addr);
+ preempt_enable();
+
+ if (WARN_ON(!(*mod)))
+ return -EINVAL;
+
+ return 0;
+}
+
+static struct plt_entry *get_ftrace_plt(struct module *mod, unsigned long addr)
+{
+ struct plt_entry *plt = mod->arch.ftrace_trampolines;
+
+ if (addr == FTRACE_ADDR)
+ return &plt[FTRACE_PLT_IDX];
+ if (addr == FTRACE_REGS_ADDR &&
+ IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS))
+ return &plt[FTRACE_REGS_PLT_IDX];
+
+ return NULL;
+}
+
+static unsigned long get_plt_addr(struct module *mod, unsigned long addr)
+{
+ struct plt_entry *plt;
+
+ plt = get_ftrace_plt(mod, addr);
+ if (!plt) {
+ pr_err("ftrace: no module PLT for %ps\n", (void *)addr);
+ return -EINVAL;
+ }
+
+ return (unsigned long)plt;
+}
+#endif
+
int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, unsigned long addr)
{
u32 old, new;
unsigned long pc;
+ long offset __maybe_unused;
pc = rec->ip + LOONGARCH_INSN_SIZE;
+#ifdef CONFIG_MODULES
+ offset = (long)pc - (long)addr;
+
+ if (offset < -SZ_128M || offset >= SZ_128M) {
+ int ret;
+ struct module *mod;
+
+ ret = __get_mod(&mod, pc);
+ if (ret)
+ return ret;
+
+ addr = get_plt_addr(mod, addr);
+
+ old_addr = get_plt_addr(mod, old_addr);
+ }
+#endif
+
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 old, new;
unsigned long pc;
+ long offset __maybe_unused;
pc = rec->ip + LOONGARCH_INSN_SIZE;
+#ifdef CONFIG_MODULES
+ offset = (long)pc - (long)addr;
+
+ if (offset < -SZ_128M || offset >= SZ_128M) {
+ int ret;
+ struct module *mod;
+
+ ret = __get_mod(&mod, pc);
+ if (ret)
+ return ret;
+
+ addr = get_plt_addr(mod, addr);
+ }
+#endif
+
old = larch_insn_gen_nop();
new = larch_insn_gen_bl(pc, addr);
{
u32 old, new;
unsigned long pc;
+ long offset __maybe_unused;
pc = rec->ip + LOONGARCH_INSN_SIZE;
+#ifdef CONFIG_MODULES
+ offset = (long)pc - (long)addr;
+
+ if (offset < -SZ_128M || offset >= SZ_128M) {
+ int ret;
+ struct module *mod;
+
+ ret = __get_mod(&mod, pc);
+ if (ret)
+ return ret;
+
+ addr = get_plt_addr(mod, addr);
+ }
+#endif
+
new = larch_insn_gen_nop();
old = larch_insn_gen_bl(pc, addr);
return larch_insn_gen_or(rd, rj, 0);
}
+u32 larch_insn_gen_lu12iw(enum loongarch_gpr rd, int imm)
+{
+ union loongarch_instruction insn;
+
+ insn.reg1i20_format.opcode = lu12iw_op;
+ insn.reg1i20_format.rd = rd;
+ insn.reg1i20_format.immediate = imm;
+
+ return insn.word;
+}
+
u32 larch_insn_gen_lu32id(enum loongarch_gpr rd, int imm)
{
union loongarch_instruction insn;
#include <linux/elf.h>
#include <linux/kernel.h>
#include <linux/module.h>
+#include <linux/ftrace.h>
Elf_Addr module_emit_got_entry(struct module *mod, Elf_Shdr *sechdrs, Elf_Addr val)
{
char *secstrings, struct module *mod)
{
unsigned int i, num_plts = 0, num_gots = 0;
- Elf_Shdr *got_sec, *plt_sec, *plt_idx_sec;
+ Elf_Shdr *got_sec, *plt_sec, *plt_idx_sec, *tramp = NULL;
/*
* Find the empty .plt sections.
mod->arch.plt.shndx = i;
else if (!strcmp(secstrings + sechdrs[i].sh_name, ".plt.idx"))
mod->arch.plt_idx.shndx = i;
+ else if (!strcmp(secstrings + sechdrs[i].sh_name, ".ftrace_trampoline"))
+ tramp = sechdrs + i;
}
if (!mod->arch.got.shndx) {
mod->arch.plt_idx.num_entries = 0;
mod->arch.plt_idx.max_entries = num_plts;
+ if (tramp) {
+ tramp->sh_type = SHT_NOBITS;
+ tramp->sh_flags = SHF_EXECINSTR | SHF_ALLOC;
+ tramp->sh_addralign = __alignof__(struct plt_entry);
+ tramp->sh_size = NR_FTRACE_PLTS * sizeof(struct plt_entry);
+ }
+
return 0;
}
#include <linux/vmalloc.h>
#include <linux/slab.h>
#include <linux/fs.h>
+#include <linux/ftrace.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <asm/alternative.h>
+#include <asm/inst.h>
static int rela_stack_push(s64 stack_value, s64 *rela_stack, size_t *rela_stack_top)
{
GFP_KERNEL, PAGE_KERNEL, 0, NUMA_NO_NODE, __builtin_return_address(0));
}
+static void module_init_ftrace_plt(const Elf_Ehdr *hdr,
+ const Elf_Shdr *sechdrs, struct module *mod)
+{
+#ifdef CONFIG_DYNAMIC_FTRACE
+ struct plt_entry *ftrace_plts;
+
+ ftrace_plts = (void *)sechdrs->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
+}
+
int module_finalize(const Elf_Ehdr *hdr,
const Elf_Shdr *sechdrs, struct module *mod)
{
for (s = sechdrs, se = sechdrs + hdr->e_shnum; s < se; s++) {
if (!strcmp(".altinstructions", secstrs + s->sh_name))
apply_alternatives((void *)s->sh_addr, (void *)s->sh_addr + s->sh_size);
+ if (!strcmp(".ftrace_trampoline", secstrs + s->sh_name))
+ module_init_ftrace_plt(hdr, s, mod);
}
return 0;