From c8921d72e390cb6fca3fb2b0c2badfda851647eb Mon Sep 17 00:00:00 2001 From: Helge Deller Date: Sun, 5 Aug 2018 00:03:29 +0200 Subject: parisc: Fix and improve kernel stack unwinding This patchset fixes and improves stack unwinding a lot: 1. Show backward stack traces with up to 30 callsites 2. Add callinfo to ENTRY_CFI() such that every assembler function will get an entry in the unwind table 3. Use constants instead of numbers in call_on_stack() 4. Do not depend on CONFIG_KALLSYMS to generate backtraces. 5. Speed up backtrace generation Make sure you have this patch to GNU as installed: https://sourceware.org/ml/binutils/2018-07/msg00474.html Without this patch, unwind info in the kernel is often wrong for various functions. Signed-off-by: Helge Deller --- arch/parisc/kernel/unwind.c | 89 +++++++++++++++++++++++++-------------------- 1 file changed, 49 insertions(+), 40 deletions(-) (limited to 'arch/parisc/kernel/unwind.c') diff --git a/arch/parisc/kernel/unwind.c b/arch/parisc/kernel/unwind.c index a4b430f440a9..5cdf13069dd9 100644 --- a/arch/parisc/kernel/unwind.c +++ b/arch/parisc/kernel/unwind.c @@ -13,7 +13,6 @@ #include #include #include -#include #include #include @@ -117,7 +116,8 @@ unwind_table_init(struct unwind_table *table, const char *name, for (; start <= end; start++) { if (start < end && start->region_end > (start+1)->region_start) { - printk("WARNING: Out of order unwind entry! %p and %p\n", start, start+1); + pr_warn("Out of order unwind entry! %px and %px\n", + start, start+1); } start->region_start += base_addr; @@ -203,25 +203,60 @@ int __init unwind_init(void) return 0; } -#ifdef CONFIG_64BIT -#define get_func_addr(fptr) fptr[2] -#else -#define get_func_addr(fptr) fptr[0] -#endif - static int unwind_special(struct unwind_frame_info *info, unsigned long pc, int frame_size) { - extern void handle_interruption(int, struct pt_regs *); - static unsigned long *hi = (unsigned long *)&handle_interruption; - - if (pc == get_func_addr(hi)) { + /* + * 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 + */ + 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 == (unsigned long) &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 == (unsigned long) &ret_from_kernel_thread || + pc == (unsigned long) &syscall_exit) { + info->prev_sp = info->prev_ip = 0; + return 1; + } + + if (pc == (unsigned long) &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 == (unsigned long) &_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 == (unsigned long) &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; } @@ -238,34 +273,8 @@ static void unwind_frame_regs(struct unwind_frame_info *info) if (e == NULL) { unsigned long sp; - dbg("Cannot find unwind entry for 0x%lx; forced unwinding\n", info->ip); - -#ifdef CONFIG_KALLSYMS - /* Handle some frequent special cases.... */ - { - char symname[KSYM_NAME_LEN]; - char *modname; - - kallsyms_lookup(info->ip, NULL, NULL, &modname, - symname); - - dbg("info->ip = 0x%lx, name = %s\n", info->ip, symname); - - if (strcmp(symname, "_switch_to_ret") == 0) { - info->prev_sp = info->sp - CALLEE_SAVE_FRAME_SIZE; - info->prev_ip = *(unsigned long *)(info->prev_sp - RP_OFFSET); - dbg("_switch_to_ret @ %lx - setting " - "prev_sp=%lx prev_ip=%lx\n", - info->ip, info->prev_sp, - info->prev_ip); - return; - } else if (strcmp(symname, "ret_from_kernel_thread") == 0 || - strcmp(symname, "syscall_exit") == 0) { - info->prev_ip = info->prev_sp = 0; - return; - } - } -#endif + 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 -- cgit v1.2.3-59-g8ed1b