diff options
Diffstat (limited to 'arch/parisc/kernel/unwind.c')
| -rw-r--r-- | arch/parisc/kernel/unwind.c | 490 |
1 files changed, 490 insertions, 0 deletions
diff --git a/arch/parisc/kernel/unwind.c b/arch/parisc/kernel/unwind.c new file mode 100644 index 000000000..86a57fb0e --- /dev/null +++ b/arch/parisc/kernel/unwind.c @@ -0,0 +1,490 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Kernel unwinding support + * + * (c) 2002-2004 Randolph Chung <tausq@debian.org> + * + * Derived partially from the IA64 implementation. The PA-RISC + * Runtime Architecture Document is also a useful reference to + * understand what is happening here + */ + +#include <linux/kernel.h> +#include <linux/init.h> +#include <linux/sched.h> +#include <linux/slab.h> +#include <linux/sort.h> + +#include <linux/uaccess.h> +#include <asm/assembly.h> +#include <asm/asm-offsets.h> +#include <asm/ptrace.h> + +#include <asm/unwind.h> +#include <asm/switch_to.h> +#include <asm/sections.h> + +/* #define DEBUG 1 */ +#ifdef DEBUG +#define dbg(x...) pr_debug(x) +#else +#define dbg(x...) +#endif + +#define KERNEL_START (KERNEL_BINARY_TEXT_START) + +extern struct unwind_table_entry __start___unwind[]; +extern struct unwind_table_entry __stop___unwind[]; + +static DEFINE_SPINLOCK(unwind_lock); +/* + * the kernel unwind block is not dynamically allocated so that + * we can call unwind_init as early in the bootup process as + * possible (before the slab allocator is initialized) + */ +static struct unwind_table kernel_unwind_table __ro_after_init; +static LIST_HEAD(unwind_tables); + +static inline const struct unwind_table_entry * +find_unwind_entry_in_table(const struct unwind_table *table, unsigned long addr) +{ + const struct unwind_table_entry *e = NULL; + unsigned long lo, hi, mid; + + lo = 0; + hi = table->length - 1; + + while (lo <= hi) { + mid = (hi - lo) / 2 + lo; + e = &table->table[mid]; + if (addr < e->region_start) + hi = mid - 1; + else if (addr > e->region_end) + lo = mid + 1; + else + return e; + } + + return NULL; +} + +static const struct unwind_table_entry * +find_unwind_entry(unsigned long addr) +{ + struct unwind_table *table; + const struct unwind_table_entry *e = NULL; + + if (addr >= kernel_unwind_table.start && + addr <= kernel_unwind_table.end) + e = find_unwind_entry_in_table(&kernel_unwind_table, addr); + else { + unsigned long flags; + + spin_lock_irqsave(&unwind_lock, flags); + list_for_each_entry(table, &unwind_tables, list) { + if (addr >= table->start && + addr <= table->end) + e = find_unwind_entry_in_table(table, addr); + if (e) { + /* Move-to-front to exploit common traces */ + list_move(&table->list, &unwind_tables); + break; + } + } + spin_unlock_irqrestore(&unwind_lock, flags); + } + + return e; +} + +static void +unwind_table_init(struct unwind_table *table, const char *name, + unsigned long base_addr, unsigned long gp, + void *table_start, void *table_end) +{ + struct unwind_table_entry *start = table_start; + struct unwind_table_entry *end = + (struct unwind_table_entry *)table_end - 1; + + table->name = name; + table->base_addr = base_addr; + table->gp = gp; + table->start = base_addr + start->region_start; + table->end = base_addr + end->region_end; + table->table = (struct unwind_table_entry *)table_start; + table->length = end - start + 1; + INIT_LIST_HEAD(&table->list); + + for (; start <= end; start++) { + if (start < end && + start->region_end > (start+1)->region_start) { + pr_warn("Out of order unwind entry! %px and %px\n", + start, start+1); + } + + start->region_start += base_addr; + start->region_end += base_addr; + } +} + +static int cmp_unwind_table_entry(const void *a, const void *b) +{ + return ((const struct unwind_table_entry *)a)->region_start + - ((const struct unwind_table_entry *)b)->region_start; +} + +static void +unwind_table_sort(struct unwind_table_entry *start, + struct unwind_table_entry *finish) +{ + sort(start, finish - start, sizeof(struct unwind_table_entry), + cmp_unwind_table_entry, NULL); +} + +struct unwind_table * +unwind_table_add(const char *name, unsigned long base_addr, + unsigned long gp, + void *start, void *end) +{ + struct unwind_table *table; + unsigned long flags; + struct unwind_table_entry *s = (struct unwind_table_entry *)start; + struct unwind_table_entry *e = (struct unwind_table_entry *)end; + + unwind_table_sort(s, e); + + table = kmalloc(sizeof(struct unwind_table), GFP_USER); + if (table == NULL) + return NULL; + unwind_table_init(table, name, base_addr, gp, start, end); + spin_lock_irqsave(&unwind_lock, flags); + list_add_tail(&table->list, &unwind_tables); + spin_unlock_irqrestore(&unwind_lock, flags); + + return table; +} + +void unwind_table_remove(struct unwind_table *table) +{ + unsigned long flags; + + spin_lock_irqsave(&unwind_lock, flags); + list_del(&table->list); + spin_unlock_irqrestore(&unwind_lock, flags); + + kfree(table); +} + +/* Called from setup_arch to import the kernel unwind info */ +int __init unwind_init(void) +{ + long start, stop; + register unsigned long gp __asm__ ("r27"); + + start = (long)&__start___unwind[0]; + stop = (long)&__stop___unwind[0]; + + dbg("unwind_init: start = 0x%lx, end = 0x%lx, entries = %lu\n", + start, stop, + (stop - start) / sizeof(struct unwind_table_entry)); + + unwind_table_init(&kernel_unwind_table, "kernel", KERNEL_START, + gp, + &__start___unwind[0], &__stop___unwind[0]); +#if 0 + { + int i; + for (i = 0; i < 10; i++) + { + printk("region 0x%x-0x%x\n", + __start___unwind[i].region_start, + __start___unwind[i].region_end); + } + } +#endif + return 0; +} + +static bool pc_is_kernel_fn(unsigned long pc, void *fn) +{ + return (unsigned long)dereference_kernel_function_descriptor(fn) == pc; +} + +static int unwind_special(struct unwind_frame_info *info, unsigned long pc, int frame_size) +{ + /* + * We have to use void * instead of a function pointer, because + * function pointers aren't a pointer to the function on 64-bit. + * Make them const so the compiler knows they live in .text + * Note: We could use dereference_kernel_function_descriptor() + * instead but we want to keep it simple here. + */ + extern void * const handle_interruption; + extern void * const ret_from_kernel_thread; + extern void * const syscall_exit; + extern void * const intr_return; + extern void * const _switch_to_ret; +#ifdef CONFIG_IRQSTACKS + extern void * const _call_on_stack; +#endif /* CONFIG_IRQSTACKS */ + + if (pc_is_kernel_fn(pc, handle_interruption)) { + struct pt_regs *regs = (struct pt_regs *)(info->sp - frame_size - PT_SZ_ALGN); + dbg("Unwinding through handle_interruption()\n"); + info->prev_sp = regs->gr[30]; + info->prev_ip = regs->iaoq[0]; + return 1; + } + + if (pc_is_kernel_fn(pc, ret_from_kernel_thread) || + pc_is_kernel_fn(pc, syscall_exit)) { + info->prev_sp = info->prev_ip = 0; + return 1; + } + + if (pc_is_kernel_fn(pc, intr_return)) { + struct pt_regs *regs; + + dbg("Found intr_return()\n"); + regs = (struct pt_regs *)(info->sp - PT_SZ_ALGN); + info->prev_sp = regs->gr[30]; + info->prev_ip = regs->iaoq[0]; + info->rp = regs->gr[2]; + return 1; + } + + if (pc_is_kernel_fn(pc, _switch_to) || + pc_is_kernel_fn(pc, _switch_to_ret)) { + info->prev_sp = info->sp - CALLEE_SAVE_FRAME_SIZE; + info->prev_ip = *(unsigned long *)(info->prev_sp - RP_OFFSET); + return 1; + } + +#ifdef CONFIG_IRQSTACKS + if (pc_is_kernel_fn(pc, _call_on_stack)) { + info->prev_sp = *(unsigned long *)(info->sp - FRAME_SIZE - REG_SZ); + info->prev_ip = *(unsigned long *)(info->sp - FRAME_SIZE - RP_OFFSET); + return 1; + } +#endif + return 0; +} + +static void unwind_frame_regs(struct unwind_frame_info *info) +{ + const struct unwind_table_entry *e; + unsigned long npc; + unsigned int insn; + long frame_size = 0; + int looking_for_rp, rpoffset = 0; + + e = find_unwind_entry(info->ip); + if (e == NULL) { + unsigned long sp; + + dbg("Cannot find unwind entry for %pS; forced unwinding\n", + (void *) info->ip); + + /* Since we are doing the unwinding blind, we don't know if + we are adjusting the stack correctly or extracting the rp + correctly. The rp is checked to see if it belongs to the + kernel text section, if not we assume we don't have a + correct stack frame and we continue to unwind the stack. + This is not quite correct, and will fail for loadable + modules. */ + sp = info->sp & ~63; + do { + unsigned long tmp; + + info->prev_sp = sp - 64; + info->prev_ip = 0; + + /* The stack is at the end inside the thread_union + * struct. If we reach data, we have reached the + * beginning of the stack and should stop unwinding. */ + if (info->prev_sp >= (unsigned long) task_thread_info(info->t) && + info->prev_sp < ((unsigned long) task_thread_info(info->t) + + THREAD_SZ_ALGN)) { + info->prev_sp = 0; + break; + } + + if (get_user(tmp, (unsigned long *)(info->prev_sp - RP_OFFSET))) + break; + info->prev_ip = tmp; + sp = info->prev_sp; + } while (!kernel_text_address(info->prev_ip)); + + info->rp = 0; + + dbg("analyzing func @ %lx with no unwind info, setting " + "prev_sp=%lx prev_ip=%lx\n", info->ip, + info->prev_sp, info->prev_ip); + } else { + dbg("e->start = 0x%x, e->end = 0x%x, Save_SP = %d, " + "Save_RP = %d, Millicode = %d size = %u\n", + e->region_start, e->region_end, e->Save_SP, e->Save_RP, + e->Millicode, e->Total_frame_size); + + looking_for_rp = e->Save_RP; + + for (npc = e->region_start; + (frame_size < (e->Total_frame_size << 3) || + looking_for_rp) && + npc < info->ip; + npc += 4) { + + insn = *(unsigned int *)npc; + + if ((insn & 0xffffc001) == 0x37de0000 || + (insn & 0xffe00001) == 0x6fc00000) { + /* ldo X(sp), sp, or stwm X,D(sp) */ + frame_size += (insn & 0x3fff) >> 1; + dbg("analyzing func @ %lx, insn=%08x @ " + "%lx, frame_size = %ld\n", info->ip, + insn, npc, frame_size); + } else if ((insn & 0xffe00009) == 0x73c00008) { + /* std,ma X,D(sp) */ + frame_size += ((insn >> 4) & 0x3ff) << 3; + dbg("analyzing func @ %lx, insn=%08x @ " + "%lx, frame_size = %ld\n", info->ip, + insn, npc, frame_size); + } else if (insn == 0x6bc23fd9) { + /* stw rp,-20(sp) */ + rpoffset = 20; + looking_for_rp = 0; + dbg("analyzing func @ %lx, insn=stw rp," + "-20(sp) @ %lx\n", info->ip, npc); + } else if (insn == 0x0fc212c1) { + /* std rp,-16(sr0,sp) */ + rpoffset = 16; + looking_for_rp = 0; + dbg("analyzing func @ %lx, insn=std rp," + "-16(sp) @ %lx\n", info->ip, npc); + } + } + + if (frame_size > e->Total_frame_size << 3) + frame_size = e->Total_frame_size << 3; + + if (!unwind_special(info, e->region_start, frame_size)) { + info->prev_sp = info->sp - frame_size; + if (e->Millicode) + info->rp = info->r31; + else if (rpoffset) + info->rp = *(unsigned long *)(info->prev_sp - rpoffset); + info->prev_ip = info->rp; + info->rp = 0; + } + + dbg("analyzing func @ %lx, setting prev_sp=%lx " + "prev_ip=%lx npc=%lx\n", info->ip, info->prev_sp, + info->prev_ip, npc); + } +} + +void unwind_frame_init(struct unwind_frame_info *info, struct task_struct *t, + struct pt_regs *regs) +{ + memset(info, 0, sizeof(struct unwind_frame_info)); + info->t = t; + info->sp = regs->gr[30]; + info->ip = regs->iaoq[0]; + info->rp = regs->gr[2]; + info->r31 = regs->gr[31]; + + dbg("(%d) Start unwind from sp=%08lx ip=%08lx\n", + t ? (int)t->pid : -1, info->sp, info->ip); +} + +void unwind_frame_init_from_blocked_task(struct unwind_frame_info *info, struct task_struct *t) +{ + struct pt_regs *r = &t->thread.regs; + struct pt_regs *r2; + + r2 = kmalloc(sizeof(struct pt_regs), GFP_ATOMIC); + if (!r2) + return; + *r2 = *r; + r2->gr[30] = r->ksp; + r2->iaoq[0] = r->kpc; + unwind_frame_init(info, t, r2); + kfree(r2); +} + +#define get_parisc_stackpointer() ({ \ + unsigned long sp; \ + __asm__("copy %%r30, %0" : "=r"(sp)); \ + (sp); \ +}) + +void unwind_frame_init_task(struct unwind_frame_info *info, + struct task_struct *task, struct pt_regs *regs) +{ + task = task ? task : current; + + if (task == current) { + struct pt_regs r; + + if (!regs) { + memset(&r, 0, sizeof(r)); + r.iaoq[0] = _THIS_IP_; + r.gr[2] = _RET_IP_; + r.gr[30] = get_parisc_stackpointer(); + regs = &r; + } + unwind_frame_init(info, task, regs); + } else { + unwind_frame_init_from_blocked_task(info, task); + } +} + +int unwind_once(struct unwind_frame_info *next_frame) +{ + unwind_frame_regs(next_frame); + + if (next_frame->prev_sp == 0 || + next_frame->prev_ip == 0) + return -1; + + next_frame->sp = next_frame->prev_sp; + next_frame->ip = next_frame->prev_ip; + next_frame->prev_sp = 0; + next_frame->prev_ip = 0; + + dbg("(%d) Continue unwind to sp=%08lx ip=%08lx\n", + next_frame->t ? (int)next_frame->t->pid : -1, + next_frame->sp, next_frame->ip); + + return 0; +} + +int unwind_to_user(struct unwind_frame_info *info) +{ + int ret; + + do { + ret = unwind_once(info); + } while (!ret && !(info->ip & 3)); + + return ret; +} + +unsigned long return_address(unsigned int level) +{ + struct unwind_frame_info info; + + /* initialize unwind info */ + unwind_frame_init_task(&info, current, NULL); + + /* unwind stack */ + level += 2; + do { + if (unwind_once(&info) < 0 || info.ip == 0) + return 0; + if (!kernel_text_address(info.ip)) + return 0; + } while (info.ip && level--); + + return info.ip; +} |