diff options
Diffstat (limited to 'samples/ftrace/ftrace-direct-modify.c')
| -rw-r--r-- | samples/ftrace/ftrace-direct-modify.c | 339 |
1 files changed, 339 insertions, 0 deletions
diff --git a/samples/ftrace/ftrace-direct-modify.c b/samples/ftrace/ftrace-direct-modify.c new file mode 100644 index 000000000000..da3a9f2091f5 --- /dev/null +++ b/samples/ftrace/ftrace-direct-modify.c @@ -0,0 +1,339 @@ +// SPDX-License-Identifier: GPL-2.0-only +#include <linux/module.h> +#include <linux/kthread.h> +#include <linux/ftrace.h> +#if !defined(CONFIG_ARM64) && !defined(CONFIG_PPC32) +#include <asm/asm-offsets.h> +#endif + +extern void my_direct_func1(void); +extern void my_direct_func2(void); + +void my_direct_func1(void) +{ + trace_printk("my direct func1\n"); +} + +void my_direct_func2(void) +{ + trace_printk("my direct func2\n"); +} + +extern void my_tramp1(void *); +extern void my_tramp2(void *); + +static unsigned long my_ip = (unsigned long)schedule; + +#ifdef CONFIG_RISCV +#include <asm/asm.h> + +asm ( +" .pushsection .text, \"ax\", @progbits\n" +" .type my_tramp1, @function\n" +" .globl my_tramp1\n" +" my_tramp1:\n" +" addi sp,sp,-2*"SZREG"\n" +" "REG_S" t0,0*"SZREG"(sp)\n" +" "REG_S" ra,1*"SZREG"(sp)\n" +" call my_direct_func1\n" +" "REG_L" t0,0*"SZREG"(sp)\n" +" "REG_L" ra,1*"SZREG"(sp)\n" +" addi sp,sp,2*"SZREG"\n" +" jr t0\n" +" .size my_tramp1, .-my_tramp1\n" +" .type my_tramp2, @function\n" +" .globl my_tramp2\n" + +" my_tramp2:\n" +" addi sp,sp,-2*"SZREG"\n" +" "REG_S" t0,0*"SZREG"(sp)\n" +" "REG_S" ra,1*"SZREG"(sp)\n" +" call my_direct_func2\n" +" "REG_L" t0,0*"SZREG"(sp)\n" +" "REG_L" ra,1*"SZREG"(sp)\n" +" addi sp,sp,2*"SZREG"\n" +" jr t0\n" +" .size my_tramp2, .-my_tramp2\n" +" .popsection\n" +); + +#endif /* CONFIG_RISCV */ + +#ifdef CONFIG_X86_64 + +#include <asm/ibt.h> +#include <asm/nospec-branch.h> + +asm ( +" .pushsection .text, \"ax\", @progbits\n" +" .type my_tramp1, @function\n" +" .globl my_tramp1\n" +" my_tramp1:" + ASM_ENDBR +" pushq %rbp\n" +" movq %rsp, %rbp\n" + CALL_DEPTH_ACCOUNT +" call my_direct_func1\n" +" leave\n" + ASM_RET +" .size my_tramp1, .-my_tramp1\n" + +" .type my_tramp2, @function\n" +" .globl my_tramp2\n" +" my_tramp2:" + ASM_ENDBR +" pushq %rbp\n" +" movq %rsp, %rbp\n" + CALL_DEPTH_ACCOUNT +" call my_direct_func2\n" +" leave\n" + ASM_RET +" .size my_tramp2, .-my_tramp2\n" +" .popsection\n" +); + +#endif /* CONFIG_X86_64 */ + +#ifdef CONFIG_S390 + +asm ( +" .pushsection .text, \"ax\", @progbits\n" +" .type my_tramp1, @function\n" +" .globl my_tramp1\n" +" my_tramp1:" +" lgr %r1,%r15\n" +" stmg %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n" +" stg %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n" +" aghi %r15,"__stringify(-STACK_FRAME_OVERHEAD)"\n" +" stg %r1,"__stringify(__SF_BACKCHAIN)"(%r15)\n" +" brasl %r14,my_direct_func1\n" +" aghi %r15,"__stringify(STACK_FRAME_OVERHEAD)"\n" +" lmg %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n" +" lg %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n" +" lgr %r1,%r0\n" +" br %r1\n" +" .size my_tramp1, .-my_tramp1\n" +" .type my_tramp2, @function\n" +" .globl my_tramp2\n" +" my_tramp2:" +" lgr %r1,%r15\n" +" stmg %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n" +" stg %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n" +" aghi %r15,"__stringify(-STACK_FRAME_OVERHEAD)"\n" +" stg %r1,"__stringify(__SF_BACKCHAIN)"(%r15)\n" +" brasl %r14,my_direct_func2\n" +" aghi %r15,"__stringify(STACK_FRAME_OVERHEAD)"\n" +" lmg %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n" +" lg %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n" +" lgr %r1,%r0\n" +" br %r1\n" +" .size my_tramp2, .-my_tramp2\n" +" .popsection\n" +); + +#endif /* CONFIG_S390 */ + +#ifdef CONFIG_ARM64 + +asm ( +" .pushsection .text, \"ax\", @progbits\n" +" .type my_tramp1, @function\n" +" .globl my_tramp1\n" +" my_tramp1:" +" hint 34\n" // bti c +" sub sp, sp, #16\n" +" stp x9, x30, [sp]\n" +" bl my_direct_func1\n" +" ldp x30, x9, [sp]\n" +" add sp, sp, #16\n" +" ret x9\n" +" .size my_tramp1, .-my_tramp1\n" + +" .type my_tramp2, @function\n" +" .globl my_tramp2\n" +" my_tramp2:" +" hint 34\n" // bti c +" sub sp, sp, #16\n" +" stp x9, x30, [sp]\n" +" bl my_direct_func2\n" +" ldp x30, x9, [sp]\n" +" add sp, sp, #16\n" +" ret x9\n" +" .size my_tramp2, .-my_tramp2\n" +" .popsection\n" +); + +#endif /* CONFIG_ARM64 */ + +#ifdef CONFIG_LOONGARCH + +asm ( +" .pushsection .text, \"ax\", @progbits\n" +" .type my_tramp1, @function\n" +" .globl my_tramp1\n" +" my_tramp1:\n" +" addi.d $sp, $sp, -16\n" +" st.d $t0, $sp, 0\n" +" st.d $ra, $sp, 8\n" +" bl my_direct_func1\n" +" ld.d $t0, $sp, 0\n" +" ld.d $ra, $sp, 8\n" +" addi.d $sp, $sp, 16\n" +" jr $t0\n" +" .size my_tramp1, .-my_tramp1\n" + +" .type my_tramp2, @function\n" +" .globl my_tramp2\n" +" my_tramp2:\n" +" addi.d $sp, $sp, -16\n" +" st.d $t0, $sp, 0\n" +" st.d $ra, $sp, 8\n" +" bl my_direct_func2\n" +" ld.d $t0, $sp, 0\n" +" ld.d $ra, $sp, 8\n" +" addi.d $sp, $sp, 16\n" +" jr $t0\n" +" .size my_tramp2, .-my_tramp2\n" +" .popsection\n" +); + +#endif /* CONFIG_LOONGARCH */ + +#ifdef CONFIG_PPC +#include <asm/ppc_asm.h> + +#ifdef CONFIG_PPC64 +#define STACK_FRAME_SIZE 48 +#else +#define STACK_FRAME_SIZE 24 +#endif + +#if defined(CONFIG_PPC64_ELF_ABI_V2) && !defined(CONFIG_PPC_KERNEL_PCREL) +#define PPC64_TOC_SAVE_AND_UPDATE \ +" std 2, 24(1)\n" \ +" bcl 20, 31, 1f\n" \ +" 1: mflr 12\n" \ +" ld 2, (99f - 1b)(12)\n" +#define PPC64_TOC_RESTORE \ +" ld 2, 24(1)\n" +#define PPC64_TOC \ +" 99: .quad .TOC.@tocbase\n" +#else +#define PPC64_TOC_SAVE_AND_UPDATE "" +#define PPC64_TOC_RESTORE "" +#define PPC64_TOC "" +#endif + +#ifdef CONFIG_PPC_FTRACE_OUT_OF_LINE +#define PPC_FTRACE_RESTORE_LR \ + PPC_LL" 0, "__stringify(PPC_LR_STKOFF)"(1)\n" \ +" mtlr 0\n" +#define PPC_FTRACE_RET \ +" blr\n" +#else +#define PPC_FTRACE_RESTORE_LR \ + PPC_LL" 0, "__stringify(PPC_LR_STKOFF)"(1)\n" \ +" mtctr 0\n" +#define PPC_FTRACE_RET \ +" mtlr 0\n" \ +" bctr\n" +#endif + +asm ( +" .pushsection .text, \"ax\", @progbits\n" +" .type my_tramp1, @function\n" +" .globl my_tramp1\n" +" my_tramp1:\n" + PPC_STL" 0, "__stringify(PPC_LR_STKOFF)"(1)\n" + PPC_STLU" 1, -"__stringify(STACK_FRAME_MIN_SIZE)"(1)\n" +" mflr 0\n" + PPC_STL" 0, "__stringify(PPC_LR_STKOFF)"(1)\n" + PPC_STLU" 1, -"__stringify(STACK_FRAME_SIZE)"(1)\n" + PPC64_TOC_SAVE_AND_UPDATE +" bl my_direct_func1\n" + PPC64_TOC_RESTORE +" addi 1, 1, "__stringify(STACK_FRAME_SIZE)"\n" + PPC_FTRACE_RESTORE_LR +" addi 1, 1, "__stringify(STACK_FRAME_MIN_SIZE)"\n" + PPC_LL" 0, "__stringify(PPC_LR_STKOFF)"(1)\n" + PPC_FTRACE_RET +" .size my_tramp1, .-my_tramp1\n" + +" .type my_tramp2, @function\n" +" .globl my_tramp2\n" +" my_tramp2:\n" + PPC_STL" 0, "__stringify(PPC_LR_STKOFF)"(1)\n" + PPC_STLU" 1, -"__stringify(STACK_FRAME_MIN_SIZE)"(1)\n" +" mflr 0\n" + PPC_STL" 0, "__stringify(PPC_LR_STKOFF)"(1)\n" + PPC_STLU" 1, -"__stringify(STACK_FRAME_SIZE)"(1)\n" + PPC64_TOC_SAVE_AND_UPDATE +" bl my_direct_func2\n" + PPC64_TOC_RESTORE +" addi 1, 1, "__stringify(STACK_FRAME_SIZE)"\n" + PPC_FTRACE_RESTORE_LR +" addi 1, 1, "__stringify(STACK_FRAME_MIN_SIZE)"\n" + PPC_LL" 0, "__stringify(PPC_LR_STKOFF)"(1)\n" + PPC_FTRACE_RET + PPC64_TOC +" .size my_tramp2, .-my_tramp2\n" +" .popsection\n" +); + +#endif /* CONFIG_PPC */ + +static struct ftrace_ops direct; + +static unsigned long my_tramp = (unsigned long)my_tramp1; +static unsigned long tramps[2] = { + (unsigned long)my_tramp1, + (unsigned long)my_tramp2, +}; + +static int simple_thread(void *arg) +{ + static int t; + int ret = 0; + + while (!kthread_should_stop()) { + set_current_state(TASK_INTERRUPTIBLE); + schedule_timeout(2 * HZ); + + if (ret) + continue; + t ^= 1; + ret = modify_ftrace_direct(&direct, tramps[t]); + if (!ret) + my_tramp = tramps[t]; + WARN_ON_ONCE(ret); + } + + return 0; +} + +static struct task_struct *simple_tsk; + +static int __init ftrace_direct_init(void) +{ + int ret; + + ftrace_set_filter_ip(&direct, (unsigned long) my_ip, 0, 0); + ret = register_ftrace_direct(&direct, my_tramp); + + if (!ret) + simple_tsk = kthread_run(simple_thread, NULL, "event-sample-fn"); + return ret; +} + +static void __exit ftrace_direct_exit(void) +{ + kthread_stop(simple_tsk); + unregister_ftrace_direct(&direct, my_tramp, true); +} + +module_init(ftrace_direct_init); +module_exit(ftrace_direct_exit); + +MODULE_AUTHOR("Steven Rostedt"); +MODULE_DESCRIPTION("Example use case of using modify_ftrace_direct()"); +MODULE_LICENSE("GPL"); |