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359 lines
8.4 KiB
359 lines
8.4 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* Test module for unwind_for_each_frame |
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*/ |
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#define pr_fmt(fmt) "test_unwind: " fmt |
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#include <asm/unwind.h> |
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#include <linux/completion.h> |
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#include <linux/kallsyms.h> |
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#include <linux/kthread.h> |
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#include <linux/module.h> |
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#include <linux/timer.h> |
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#include <linux/slab.h> |
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#include <linux/string.h> |
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#include <linux/kprobes.h> |
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#include <linux/wait.h> |
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#include <asm/irq.h> |
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#define BT_BUF_SIZE (PAGE_SIZE * 4) |
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/* |
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* To avoid printk line limit split backtrace by lines |
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*/ |
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static void print_backtrace(char *bt) |
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{ |
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char *p; |
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while (true) { |
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p = strsep(&bt, "\n"); |
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if (!p) |
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break; |
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pr_err("%s\n", p); |
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} |
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} |
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/* |
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* Calls unwind_for_each_frame(task, regs, sp) and verifies that the result |
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* contains unwindme_func2 followed by unwindme_func1. |
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*/ |
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static noinline int test_unwind(struct task_struct *task, struct pt_regs *regs, |
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unsigned long sp) |
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{ |
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int frame_count, prev_is_func2, seen_func2_func1; |
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const int max_frames = 128; |
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struct unwind_state state; |
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size_t bt_pos = 0; |
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int ret = 0; |
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char *bt; |
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bt = kmalloc(BT_BUF_SIZE, GFP_ATOMIC); |
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if (!bt) { |
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pr_err("failed to allocate backtrace buffer\n"); |
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return -ENOMEM; |
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} |
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/* Unwind. */ |
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frame_count = 0; |
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prev_is_func2 = 0; |
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seen_func2_func1 = 0; |
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unwind_for_each_frame(&state, task, regs, sp) { |
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unsigned long addr = unwind_get_return_address(&state); |
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char sym[KSYM_SYMBOL_LEN]; |
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if (frame_count++ == max_frames) |
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break; |
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if (state.reliable && !addr) { |
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pr_err("unwind state reliable but addr is 0\n"); |
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ret = -EINVAL; |
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break; |
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} |
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sprint_symbol(sym, addr); |
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if (bt_pos < BT_BUF_SIZE) { |
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bt_pos += snprintf(bt + bt_pos, BT_BUF_SIZE - bt_pos, |
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state.reliable ? " [%-7s%px] %pSR\n" : |
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"([%-7s%px] %pSR)\n", |
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stack_type_name(state.stack_info.type), |
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(void *)state.sp, (void *)state.ip); |
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if (bt_pos >= BT_BUF_SIZE) |
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pr_err("backtrace buffer is too small\n"); |
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} |
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frame_count += 1; |
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if (prev_is_func2 && str_has_prefix(sym, "unwindme_func1")) |
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seen_func2_func1 = 1; |
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prev_is_func2 = str_has_prefix(sym, "unwindme_func2"); |
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} |
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/* Check the results. */ |
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if (unwind_error(&state)) { |
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pr_err("unwind error\n"); |
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ret = -EINVAL; |
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} |
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if (!seen_func2_func1) { |
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pr_err("unwindme_func2 and unwindme_func1 not found\n"); |
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ret = -EINVAL; |
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} |
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if (frame_count == max_frames) { |
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pr_err("Maximum number of frames exceeded\n"); |
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ret = -EINVAL; |
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} |
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if (ret) |
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print_backtrace(bt); |
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kfree(bt); |
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return ret; |
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} |
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/* State of the task being unwound. */ |
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struct unwindme { |
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int flags; |
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int ret; |
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struct task_struct *task; |
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struct completion task_ready; |
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wait_queue_head_t task_wq; |
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unsigned long sp; |
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}; |
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static struct unwindme *unwindme; |
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/* Values of unwindme.flags. */ |
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#define UWM_DEFAULT 0x0 |
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#define UWM_THREAD 0x1 /* Unwind a separate task. */ |
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#define UWM_REGS 0x2 /* Pass regs to test_unwind(). */ |
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#define UWM_SP 0x4 /* Pass sp to test_unwind(). */ |
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#define UWM_CALLER 0x8 /* Unwind starting from caller. */ |
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#define UWM_SWITCH_STACK 0x10 /* Use call_on_stack. */ |
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#define UWM_IRQ 0x20 /* Unwind from irq context. */ |
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#define UWM_PGM 0x40 /* Unwind from program check handler. */ |
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static __always_inline unsigned long get_psw_addr(void) |
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{ |
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unsigned long psw_addr; |
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asm volatile( |
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"basr %[psw_addr],0\n" |
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: [psw_addr] "=d" (psw_addr)); |
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return psw_addr; |
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} |
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#ifdef CONFIG_KPROBES |
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static int pgm_pre_handler(struct kprobe *p, struct pt_regs *regs) |
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{ |
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struct unwindme *u = unwindme; |
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u->ret = test_unwind(NULL, (u->flags & UWM_REGS) ? regs : NULL, |
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(u->flags & UWM_SP) ? u->sp : 0); |
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return 0; |
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} |
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#endif |
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/* This function may or may not appear in the backtrace. */ |
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static noinline int unwindme_func4(struct unwindme *u) |
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{ |
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if (!(u->flags & UWM_CALLER)) |
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u->sp = current_frame_address(); |
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if (u->flags & UWM_THREAD) { |
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complete(&u->task_ready); |
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wait_event(u->task_wq, kthread_should_park()); |
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kthread_parkme(); |
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return 0; |
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#ifdef CONFIG_KPROBES |
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} else if (u->flags & UWM_PGM) { |
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struct kprobe kp; |
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int ret; |
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unwindme = u; |
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memset(&kp, 0, sizeof(kp)); |
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kp.symbol_name = "do_report_trap"; |
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kp.pre_handler = pgm_pre_handler; |
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ret = register_kprobe(&kp); |
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if (ret < 0) { |
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pr_err("register_kprobe failed %d\n", ret); |
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return -EINVAL; |
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} |
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/* |
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* Trigger operation exception; use insn notation to bypass |
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* llvm's integrated assembler sanity checks. |
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*/ |
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asm volatile( |
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" .insn e,0x0000\n" /* illegal opcode */ |
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"0: nopr %%r7\n" |
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EX_TABLE(0b, 0b) |
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:); |
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unregister_kprobe(&kp); |
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unwindme = NULL; |
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return u->ret; |
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#endif |
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} else { |
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struct pt_regs regs; |
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memset(®s, 0, sizeof(regs)); |
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regs.psw.addr = get_psw_addr(); |
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regs.gprs[15] = current_stack_pointer(); |
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return test_unwind(NULL, |
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(u->flags & UWM_REGS) ? ®s : NULL, |
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(u->flags & UWM_SP) ? u->sp : 0); |
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} |
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} |
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/* This function may or may not appear in the backtrace. */ |
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static noinline int unwindme_func3(struct unwindme *u) |
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{ |
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u->sp = current_frame_address(); |
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return unwindme_func4(u); |
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} |
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/* This function must appear in the backtrace. */ |
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static noinline int unwindme_func2(struct unwindme *u) |
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{ |
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unsigned long flags; |
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int rc; |
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if (u->flags & UWM_SWITCH_STACK) { |
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local_irq_save(flags); |
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local_mcck_disable(); |
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rc = call_on_stack(1, S390_lowcore.nodat_stack, |
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int, unwindme_func3, struct unwindme *, u); |
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local_mcck_enable(); |
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local_irq_restore(flags); |
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return rc; |
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} else { |
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return unwindme_func3(u); |
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} |
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} |
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/* This function must follow unwindme_func2 in the backtrace. */ |
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static noinline int unwindme_func1(void *u) |
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{ |
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return unwindme_func2((struct unwindme *)u); |
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} |
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static void unwindme_timer_fn(struct timer_list *unused) |
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{ |
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struct unwindme *u = READ_ONCE(unwindme); |
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if (u) { |
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unwindme = NULL; |
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u->task = NULL; |
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u->ret = unwindme_func1(u); |
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complete(&u->task_ready); |
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} |
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} |
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static struct timer_list unwind_timer; |
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static int test_unwind_irq(struct unwindme *u) |
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{ |
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unwindme = u; |
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init_completion(&u->task_ready); |
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timer_setup(&unwind_timer, unwindme_timer_fn, 0); |
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mod_timer(&unwind_timer, jiffies + 1); |
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wait_for_completion(&u->task_ready); |
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return u->ret; |
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} |
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/* Spawns a task and passes it to test_unwind(). */ |
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static int test_unwind_task(struct unwindme *u) |
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{ |
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struct task_struct *task; |
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int ret; |
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/* Initialize thread-related fields. */ |
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init_completion(&u->task_ready); |
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init_waitqueue_head(&u->task_wq); |
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/* |
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* Start the task and wait until it reaches unwindme_func4() and sleeps |
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* in (task_ready, unwind_done] range. |
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*/ |
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task = kthread_run(unwindme_func1, u, "%s", __func__); |
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if (IS_ERR(task)) { |
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pr_err("kthread_run() failed\n"); |
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return PTR_ERR(task); |
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} |
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/* |
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* Make sure task reaches unwindme_func4 before parking it, |
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* we might park it before kthread function has been executed otherwise |
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*/ |
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wait_for_completion(&u->task_ready); |
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kthread_park(task); |
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/* Unwind. */ |
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ret = test_unwind(task, NULL, (u->flags & UWM_SP) ? u->sp : 0); |
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kthread_stop(task); |
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return ret; |
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} |
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static int test_unwind_flags(int flags) |
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{ |
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struct unwindme u; |
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u.flags = flags; |
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if (u.flags & UWM_THREAD) |
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return test_unwind_task(&u); |
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else if (u.flags & UWM_IRQ) |
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return test_unwind_irq(&u); |
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else |
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return unwindme_func1(&u); |
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} |
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static int test_unwind_init(void) |
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{ |
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int failed = 0; |
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int total = 0; |
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#define TEST(flags) \ |
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do { \ |
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pr_info("[ RUN ] " #flags "\n"); \ |
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total++; \ |
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if (!test_unwind_flags((flags))) { \ |
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pr_info("[ OK ] " #flags "\n"); \ |
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} else { \ |
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pr_err("[ FAILED ] " #flags "\n"); \ |
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failed++; \ |
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} \ |
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} while (0) |
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pr_info("running stack unwinder tests"); |
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TEST(UWM_DEFAULT); |
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TEST(UWM_SP); |
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TEST(UWM_REGS); |
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TEST(UWM_SWITCH_STACK); |
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TEST(UWM_SP | UWM_REGS); |
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TEST(UWM_CALLER | UWM_SP); |
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TEST(UWM_CALLER | UWM_SP | UWM_REGS); |
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TEST(UWM_CALLER | UWM_SP | UWM_REGS | UWM_SWITCH_STACK); |
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TEST(UWM_THREAD); |
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TEST(UWM_THREAD | UWM_SP); |
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TEST(UWM_THREAD | UWM_CALLER | UWM_SP); |
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TEST(UWM_IRQ); |
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TEST(UWM_IRQ | UWM_SWITCH_STACK); |
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TEST(UWM_IRQ | UWM_SP); |
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TEST(UWM_IRQ | UWM_REGS); |
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TEST(UWM_IRQ | UWM_SP | UWM_REGS); |
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TEST(UWM_IRQ | UWM_CALLER | UWM_SP); |
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TEST(UWM_IRQ | UWM_CALLER | UWM_SP | UWM_REGS); |
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TEST(UWM_IRQ | UWM_CALLER | UWM_SP | UWM_REGS | UWM_SWITCH_STACK); |
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#ifdef CONFIG_KPROBES |
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TEST(UWM_PGM); |
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TEST(UWM_PGM | UWM_SP); |
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TEST(UWM_PGM | UWM_REGS); |
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TEST(UWM_PGM | UWM_SP | UWM_REGS); |
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#endif |
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#undef TEST |
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if (failed) { |
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pr_err("%d of %d stack unwinder tests failed", failed, total); |
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WARN(1, "%d of %d stack unwinder tests failed", failed, total); |
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} else { |
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pr_info("all %d stack unwinder tests passed", total); |
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} |
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return failed ? -EINVAL : 0; |
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} |
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static void test_unwind_exit(void) |
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{ |
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} |
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module_init(test_unwind_init); |
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module_exit(test_unwind_exit); |
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MODULE_LICENSE("GPL");
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