diff options
Diffstat (limited to 'arch/s390/kernel/unwind_bc.c')
| -rw-r--r-- | arch/s390/kernel/unwind_bc.c | 182 |
1 files changed, 182 insertions, 0 deletions
diff --git a/arch/s390/kernel/unwind_bc.c b/arch/s390/kernel/unwind_bc.c new file mode 100644 index 000000000..707fd99f6 --- /dev/null +++ b/arch/s390/kernel/unwind_bc.c @@ -0,0 +1,182 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#include <linux/sched.h> +#include <linux/sched/task.h> +#include <linux/sched/task_stack.h> +#include <linux/interrupt.h> +#include <asm/sections.h> +#include <asm/ptrace.h> +#include <asm/bitops.h> +#include <asm/stacktrace.h> +#include <asm/unwind.h> + +unsigned long unwind_get_return_address(struct unwind_state *state) +{ + if (unwind_done(state)) + return 0; + return __kernel_text_address(state->ip) ? state->ip : 0; +} +EXPORT_SYMBOL_GPL(unwind_get_return_address); + +static bool outside_of_stack(struct unwind_state *state, unsigned long sp) +{ + return (sp <= state->sp) || + (sp > state->stack_info.end - sizeof(struct stack_frame)); +} + +static bool update_stack_info(struct unwind_state *state, unsigned long sp) +{ + struct stack_info *info = &state->stack_info; + unsigned long *mask = &state->stack_mask; + + /* New stack pointer leaves the current stack */ + if (get_stack_info(sp, state->task, info, mask) != 0 || + !on_stack(info, sp, sizeof(struct stack_frame))) + /* 'sp' does not point to a valid stack */ + return false; + return true; +} + +static inline bool is_final_pt_regs(struct unwind_state *state, + struct pt_regs *regs) +{ + /* user mode or kernel thread pt_regs at the bottom of task stack */ + if (task_pt_regs(state->task) == regs) + return true; + + /* user mode pt_regs at the bottom of irq stack */ + return state->stack_info.type == STACK_TYPE_IRQ && + state->stack_info.end - sizeof(struct pt_regs) == (unsigned long)regs && + READ_ONCE_NOCHECK(regs->psw.mask) & PSW_MASK_PSTATE; +} + +bool unwind_next_frame(struct unwind_state *state) +{ + struct stack_info *info = &state->stack_info; + struct stack_frame *sf; + struct pt_regs *regs; + unsigned long sp, ip; + bool reliable; + + regs = state->regs; + if (unlikely(regs)) { + sp = state->sp; + sf = (struct stack_frame *) sp; + ip = READ_ONCE_NOCHECK(sf->gprs[8]); + reliable = false; + regs = NULL; + if (!__kernel_text_address(ip)) { + /* skip bogus %r14 */ + state->regs = NULL; + return unwind_next_frame(state); + } + } else { + sf = (struct stack_frame *) state->sp; + sp = READ_ONCE_NOCHECK(sf->back_chain); + if (likely(sp)) { + /* Non-zero back-chain points to the previous frame */ + if (unlikely(outside_of_stack(state, sp))) { + if (!update_stack_info(state, sp)) + goto out_err; + } + sf = (struct stack_frame *) sp; + ip = READ_ONCE_NOCHECK(sf->gprs[8]); + reliable = true; + } else { + /* No back-chain, look for a pt_regs structure */ + sp = state->sp + STACK_FRAME_OVERHEAD; + if (!on_stack(info, sp, sizeof(struct pt_regs))) + goto out_err; + regs = (struct pt_regs *) sp; + if (is_final_pt_regs(state, regs)) + goto out_stop; + ip = READ_ONCE_NOCHECK(regs->psw.addr); + sp = READ_ONCE_NOCHECK(regs->gprs[15]); + if (unlikely(outside_of_stack(state, sp))) { + if (!update_stack_info(state, sp)) + goto out_err; + } + reliable = true; + } + } + + /* Sanity check: ABI requires SP to be aligned 8 bytes. */ + if (sp & 0x7) + goto out_err; + + ip = ftrace_graph_ret_addr(state->task, &state->graph_idx, ip, (void *) sp); + + /* Update unwind state */ + state->sp = sp; + state->ip = ip; + state->regs = regs; + state->reliable = reliable; + return true; + +out_err: + state->error = true; +out_stop: + state->stack_info.type = STACK_TYPE_UNKNOWN; + return false; +} +EXPORT_SYMBOL_GPL(unwind_next_frame); + +void __unwind_start(struct unwind_state *state, struct task_struct *task, + struct pt_regs *regs, unsigned long first_frame) +{ + struct stack_info *info = &state->stack_info; + struct stack_frame *sf; + unsigned long ip, sp; + + memset(state, 0, sizeof(*state)); + state->task = task; + state->regs = regs; + + /* Don't even attempt to start from user mode regs: */ + if (regs && user_mode(regs)) { + info->type = STACK_TYPE_UNKNOWN; + return; + } + + /* Get the instruction pointer from pt_regs or the stack frame */ + if (regs) { + ip = regs->psw.addr; + sp = regs->gprs[15]; + } else if (task == current) { + sp = current_frame_address(); + } else { + sp = task->thread.ksp; + } + + /* Get current stack pointer and initialize stack info */ + if (!update_stack_info(state, sp)) { + /* Something is wrong with the stack pointer */ + info->type = STACK_TYPE_UNKNOWN; + state->error = true; + return; + } + + if (!regs) { + /* Stack frame is within valid stack */ + sf = (struct stack_frame *)sp; + ip = READ_ONCE_NOCHECK(sf->gprs[8]); + } + + ip = ftrace_graph_ret_addr(state->task, &state->graph_idx, ip, NULL); + + /* Update unwind state */ + state->sp = sp; + state->ip = ip; + state->reliable = true; + + if (!first_frame) + return; + /* Skip through the call chain to the specified starting frame */ + while (!unwind_done(state)) { + if (on_stack(&state->stack_info, first_frame, sizeof(struct stack_frame))) { + if (state->sp >= first_frame) + break; + } + unwind_next_frame(state); + } +} +EXPORT_SYMBOL_GPL(__unwind_start); |