Re: [PATCH v2] parisc: Fix and improve kernel stack unwinding

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This patchset fixes and improves stack unwinding a lot:
1. Show backward stack traces with up to 30 callsites
2. Do not depend on CONFIG_KALLSYMS to generate backtraces. This is done
   by adding proper unwind entries for some of the used assembler
   functions.
3. 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 <deller@xxxxxx>

diff --git a/arch/parisc/include/asm/assembly.h b/arch/parisc/include/asm/assembly.h
index 60e6f07b7e32..3f8d90a965a9 100644
--- a/arch/parisc/include/asm/assembly.h
+++ b/arch/parisc/include/asm/assembly.h
@@ -36,6 +36,7 @@
 #define RP_OFFSET	16
 #define FRAME_SIZE	128
 #define CALLEE_REG_FRAME_SIZE	144
+#define REG_SZ	8
 #define ASM_ULONG_INSN	.dword
 #else	/* CONFIG_64BIT */
 #define LDREG	ldw
@@ -50,6 +51,7 @@
 #define RP_OFFSET	20
 #define FRAME_SIZE	64
 #define CALLEE_REG_FRAME_SIZE	128
+#define REG_SZ	4
 #define ASM_ULONG_INSN	.word
 #endif
 
diff --git a/arch/parisc/include/asm/linkage.h b/arch/parisc/include/asm/linkage.h
index 9a69bf6fc4b6..501cbe5e8b95 100644
--- a/arch/parisc/include/asm/linkage.h
+++ b/arch/parisc/include/asm/linkage.h
@@ -31,11 +31,16 @@
 	END(name)
 #endif
 
-#define ENTRY_CFI(name) \
+#define ENTRY_CFI(name, ...) \
 	ENTRY(name)	ASM_NL\
+	.proc		ASM_NL\
+	.callinfo __VA_ARGS__	ASM_NL\
+	.entry		ASM_NL\
 	CFI_STARTPROC
 
 #define ENDPROC_CFI(name) \
+	.exit		ASM_NL\
+	.procend	ASM_NL\
 	ENDPROC(name)	ASM_NL\
 	CFI_ENDPROC
 
diff --git a/arch/parisc/include/asm/unwind.h b/arch/parisc/include/asm/unwind.h
index c73a3ee20226..f133b7efbebb 100644
--- a/arch/parisc/include/asm/unwind.h
+++ b/arch/parisc/include/asm/unwind.h
@@ -4,6 +4,9 @@
 
 #include <linux/list.h>
 
+/* Max number of levels to backtrace */
+#define MAX_UNWIND_ENTRIES	30
+
 /* From ABI specifications */
 struct unwind_table_entry {
 	unsigned int region_start;
diff --git a/arch/parisc/kernel/entry.S b/arch/parisc/kernel/entry.S
index e95207c0565e..8e176125f941 100644
--- a/arch/parisc/kernel/entry.S
+++ b/arch/parisc/kernel/entry.S
@@ -764,7 +764,6 @@ END(fault_vector_11)
 #endif
 	/* Fault vector is separately protected and *must* be on its own page */
 	.align		PAGE_SIZE
-ENTRY(end_fault_vector)
 
 	.import		handle_interruption,code
 	.import		do_cpu_irq_mask,code
@@ -776,7 +775,6 @@ ENTRY(end_fault_vector)
 	 */
 
 ENTRY_CFI(ret_from_kernel_thread)
-
 	/* Call schedule_tail first though */
 	BL	schedule_tail, %r2
 	nop
@@ -815,8 +813,9 @@ ENTRY_CFI(_switch_to)
 	LDREG	TASK_THREAD_INFO(%r25), %r25
 	bv	%r0(%r2)
 	mtctl   %r25,%cr30
+ENDPROC_CFI(_switch_to)
 
-_switch_to_ret:
+ENTRY_CFI(_switch_to_ret)
 	mtctl	%r0, %cr0		/* Needed for single stepping */
 	callee_rest
 	callee_rest_float
@@ -824,7 +823,7 @@ _switch_to_ret:
 	LDREG	-RP_OFFSET(%r30), %r2
 	bv	%r0(%r2)
 	copy	%r26, %r28
-ENDPROC_CFI(_switch_to)
+ENDPROC_CFI(_switch_to_ret)
 
 	/*
 	 * Common rfi return path for interruptions, kernel execve, and
@@ -885,12 +884,14 @@ ENTRY_CFI(syscall_exit_rfi)
 	STREG   %r19,PT_SR5(%r16)
 	STREG   %r19,PT_SR6(%r16)
 	STREG   %r19,PT_SR7(%r16)
+ENDPROC_CFI(syscall_exit_rfi)
 
-intr_return:
+ENTRY_CFI(intr_return)
 	/* check for reschedule */
 	mfctl   %cr30,%r1
 	LDREG   TI_FLAGS(%r1),%r19	/* sched.h: TIF_NEED_RESCHED */
 	bb,<,n	%r19,31-TIF_NEED_RESCHED,intr_do_resched /* forward */
+ENDPROC_CFI(intr_return)
 
 	.import do_notify_resume,code
 intr_check_sig:
@@ -1046,7 +1047,6 @@ intr_extint:
 
 	b	do_cpu_irq_mask
 	ldo	R%intr_return(%r2), %r2	/* return to intr_return, not here */
-ENDPROC_CFI(syscall_exit_rfi)
 
 
 	/* Generic interruptions (illegal insn, unaligned, page fault, etc) */
@@ -1997,12 +1997,9 @@ ENDPROC_CFI(syscall_exit)
 	.align L1_CACHE_BYTES
 	.globl mcount
 	.type  mcount, @function
-ENTRY(mcount)
+ENTRY_CFI(mcount, caller)
 _mcount:
 	.export _mcount,data
-	.proc
-	.callinfo caller,frame=0
-	.entry
 	/*
 	 * The 64bit mcount() function pointer needs 4 dwords, of which the
 	 * first two are free.  We optimize it here and put 2 instructions for
@@ -2024,18 +2021,13 @@ ftrace_stub:
 	.dword mcount
 	.dword 0 /* code in head.S puts value of global gp here */
 #endif
-	.exit
-	.procend
-ENDPROC(mcount)
+ENDPROC_CFI(mcount)
 
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 	.align 8
 	.globl return_to_handler
 	.type  return_to_handler, @function
-ENTRY_CFI(return_to_handler)
-	.proc
-	.callinfo caller,frame=FRAME_SIZE
-	.entry
+ENTRY_CFI(return_to_handler, caller,frame=FRAME_SIZE)
 	.export parisc_return_to_handler,data
 parisc_return_to_handler:
 	copy %r3,%r1
@@ -2074,8 +2066,6 @@ parisc_return_to_handler:
 	bv	%r0(%rp)
 #endif
 	LDREGM -FRAME_SIZE(%sp),%r3
-	.exit
-	.procend
 ENDPROC_CFI(return_to_handler)
 
 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
@@ -2085,31 +2075,30 @@ ENDPROC_CFI(return_to_handler)
 #ifdef CONFIG_IRQSTACKS
 /* void call_on_stack(unsigned long param1, void *func,
 		      unsigned long new_stack) */
-ENTRY_CFI(call_on_stack)
+ENTRY_CFI(call_on_stack, FRAME=2*FRAME_SIZE,CALLS,SAVE_RP,SAVE_SP)
 	copy	%sp, %r1
 
 	/* Regarding the HPPA calling conventions for function pointers,
 	   we assume the PIC register is not changed across call.  For
 	   CONFIG_64BIT, the argument pointer is left to point at the
 	   argument region allocated for the call to call_on_stack. */
+
+	/* Switch to new stack.  We allocate two frames.  */
+	ldo	2*FRAME_SIZE(%arg2), %sp
 # ifdef CONFIG_64BIT
-	/* Switch to new stack.  We allocate two 128 byte frames.  */
-	ldo	256(%arg2), %sp
 	/* Save previous stack pointer and return pointer in frame marker */
-	STREG	%rp, -144(%sp)
+	STREG	%rp, -FRAME_SIZE-RP_OFFSET(%sp)
 	/* Calls always use function descriptor */
 	LDREG	16(%arg1), %arg1
 	bve,l	(%arg1), %rp
-	STREG	%r1, -136(%sp)
-	LDREG	-144(%sp), %rp
+	STREG	%r1, -FRAME_SIZE-REG_SZ(%sp)
+	LDREG	-FRAME_SIZE-RP_OFFSET(%sp), %rp
 	bve	(%rp)
-	LDREG	-136(%sp), %sp
+	LDREG	-FRAME_SIZE-REG_SZ(%sp), %sp
 # else
-	/* Switch to new stack.  We allocate two 64 byte frames.  */
-	ldo	128(%arg2), %sp
 	/* Save previous stack pointer and return pointer in frame marker */
-	STREG	%r1, -68(%sp)
-	STREG	%rp, -84(%sp)
+	STREG	%r1, -FRAME_SIZE-REG_SZ(%sp)
+	STREG	%rp, -FRAME_SIZE-RP_OFFSET(%sp)
 	/* Calls use function descriptor if PLABEL bit is set */
 	bb,>=,n	%arg1, 30, 1f
 	depwi	0,31,2, %arg1
@@ -2117,9 +2106,9 @@ ENTRY_CFI(call_on_stack)
 1:
 	be,l	0(%sr4,%arg1), %sr0, %r31
 	copy	%r31, %rp
-	LDREG	-84(%sp), %rp
+	LDREG	-FRAME_SIZE-RP_OFFSET(%sp), %rp
 	bv	(%rp)
-	LDREG	-68(%sp), %sp
+	LDREG	-FRAME_SIZE-REG_SZ(%sp), %sp
 # endif /* CONFIG_64BIT */
 ENDPROC_CFI(call_on_stack)
 #endif /* CONFIG_IRQSTACKS */
diff --git a/arch/parisc/kernel/pacache.S b/arch/parisc/kernel/pacache.S
index 22e6374ece44..2db56d4db174 100644
--- a/arch/parisc/kernel/pacache.S
+++ b/arch/parisc/kernel/pacache.S
@@ -44,10 +44,6 @@
 	.align	16
 
 ENTRY_CFI(flush_tlb_all_local)
-	.proc
-	.callinfo NO_CALLS
-	.entry
-
 	/*
 	 * The pitlbe and pdtlbe instructions should only be used to
 	 * flush the entire tlb. Also, there needs to be no intervening
@@ -189,18 +185,11 @@ fdtdone:
 
 2:      bv		%r0(%r2)
 	nop
-
-	.exit
-	.procend
 ENDPROC_CFI(flush_tlb_all_local)
 
 	.import cache_info,data
 
 ENTRY_CFI(flush_instruction_cache_local)
-	.proc
-	.callinfo NO_CALLS
-	.entry
-
 	load32		cache_info, %r1
 
 	/* Flush Instruction Cache */
@@ -256,18 +245,11 @@ fisync:
 	mtsm		%r22			/* restore I-bit */
 	bv		%r0(%r2)
 	nop
-	.exit
-
-	.procend
 ENDPROC_CFI(flush_instruction_cache_local)
 
 
 	.import cache_info, data
 ENTRY_CFI(flush_data_cache_local)
-	.proc
-	.callinfo NO_CALLS
-	.entry
-
 	load32		cache_info, %r1
 
 	/* Flush Data Cache */
@@ -324,9 +306,6 @@ fdsync:
 	mtsm		%r22			/* restore I-bit */
 	bv		%r0(%r2)
 	nop
-	.exit
-
-	.procend
 ENDPROC_CFI(flush_data_cache_local)
 
 /* Macros to serialize TLB purge operations on SMP.  */
@@ -361,10 +340,6 @@ ENDPROC_CFI(flush_data_cache_local)
 /* Clear page using kernel mapping.  */
 
 ENTRY_CFI(clear_page_asm)
-	.proc
-	.callinfo NO_CALLS
-	.entry
-
 #ifdef CONFIG_64BIT
 
 	/* Unroll the loop.  */
@@ -423,18 +398,11 @@ ENTRY_CFI(clear_page_asm)
 #endif
 	bv		%r0(%r2)
 	nop
-	.exit
-
-	.procend
 ENDPROC_CFI(clear_page_asm)
 
 /* Copy page using kernel mapping.  */
 
 ENTRY_CFI(copy_page_asm)
-	.proc
-	.callinfo NO_CALLS
-	.entry
-
 #ifdef CONFIG_64BIT
 	/* PA8x00 CPUs can consume 2 loads or 1 store per cycle.
 	 * Unroll the loop by hand and arrange insn appropriately.
@@ -541,9 +509,6 @@ ENTRY_CFI(copy_page_asm)
 #endif
 	bv		%r0(%r2)
 	nop
-	.exit
-
-	.procend
 ENDPROC_CFI(copy_page_asm)
 
 /*
@@ -597,10 +562,6 @@ ENDPROC_CFI(copy_page_asm)
 	 */
 
 ENTRY_CFI(copy_user_page_asm)
-	.proc
-	.callinfo NO_CALLS
-	.entry
-
 	/* Convert virtual `to' and `from' addresses to physical addresses.
 	   Move `from' physical address to non shadowed register.  */
 	ldil		L%(__PAGE_OFFSET), %r1
@@ -749,16 +710,9 @@ ENTRY_CFI(copy_user_page_asm)
 
 	bv		%r0(%r2)
 	nop
-	.exit
-
-	.procend
 ENDPROC_CFI(copy_user_page_asm)
 
 ENTRY_CFI(clear_user_page_asm)
-	.proc
-	.callinfo NO_CALLS
-	.entry
-
 	tophys_r1	%r26
 
 	ldil		L%(TMPALIAS_MAP_START), %r28
@@ -835,16 +789,9 @@ ENTRY_CFI(clear_user_page_asm)
 
 	bv		%r0(%r2)
 	nop
-	.exit
-
-	.procend
 ENDPROC_CFI(clear_user_page_asm)
 
 ENTRY_CFI(flush_dcache_page_asm)
-	.proc
-	.callinfo NO_CALLS
-	.entry
-
 	ldil		L%(TMPALIAS_MAP_START), %r28
 #ifdef CONFIG_64BIT
 #if (TMPALIAS_MAP_START >= 0x80000000)
@@ -902,16 +849,9 @@ ENTRY_CFI(flush_dcache_page_asm)
 	sync
 	bv		%r0(%r2)
 	nop
-	.exit
-
-	.procend
 ENDPROC_CFI(flush_dcache_page_asm)
 
 ENTRY_CFI(flush_icache_page_asm)
-	.proc
-	.callinfo NO_CALLS
-	.entry
-
 	ldil		L%(TMPALIAS_MAP_START), %r28
 #ifdef CONFIG_64BIT
 #if (TMPALIAS_MAP_START >= 0x80000000)
@@ -976,16 +916,9 @@ ENTRY_CFI(flush_icache_page_asm)
 	sync
 	bv		%r0(%r2)
 	nop
-	.exit
-
-	.procend
 ENDPROC_CFI(flush_icache_page_asm)
 
 ENTRY_CFI(flush_kernel_dcache_page_asm)
-	.proc
-	.callinfo NO_CALLS
-	.entry
-
 	ldil		L%dcache_stride, %r1
 	ldw		R%dcache_stride(%r1), %r23
 
@@ -1019,16 +952,9 @@ ENTRY_CFI(flush_kernel_dcache_page_asm)
 	sync
 	bv		%r0(%r2)
 	nop
-	.exit
-
-	.procend
 ENDPROC_CFI(flush_kernel_dcache_page_asm)
 
 ENTRY_CFI(purge_kernel_dcache_page_asm)
-	.proc
-	.callinfo NO_CALLS
-	.entry
-
 	ldil		L%dcache_stride, %r1
 	ldw		R%dcache_stride(%r1), %r23
 
@@ -1061,16 +987,9 @@ ENTRY_CFI(purge_kernel_dcache_page_asm)
 	sync
 	bv		%r0(%r2)
 	nop
-	.exit
-
-	.procend
 ENDPROC_CFI(purge_kernel_dcache_page_asm)
 
 ENTRY_CFI(flush_user_dcache_range_asm)
-	.proc
-	.callinfo NO_CALLS
-	.entry
-
 	ldil		L%dcache_stride, %r1
 	ldw		R%dcache_stride(%r1), %r23
 	ldo		-1(%r23), %r21
@@ -1082,16 +1001,9 @@ ENTRY_CFI(flush_user_dcache_range_asm)
 	sync
 	bv		%r0(%r2)
 	nop
-	.exit
-
-	.procend
 ENDPROC_CFI(flush_user_dcache_range_asm)
 
 ENTRY_CFI(flush_kernel_dcache_range_asm)
-	.proc
-	.callinfo NO_CALLS
-	.entry
-
 	ldil		L%dcache_stride, %r1
 	ldw		R%dcache_stride(%r1), %r23
 	ldo		-1(%r23), %r21
@@ -1104,16 +1016,9 @@ ENTRY_CFI(flush_kernel_dcache_range_asm)
 	syncdma
 	bv		%r0(%r2)
 	nop
-	.exit
-
-	.procend
 ENDPROC_CFI(flush_kernel_dcache_range_asm)
 
 ENTRY_CFI(purge_kernel_dcache_range_asm)
-	.proc
-	.callinfo NO_CALLS
-	.entry
-
 	ldil		L%dcache_stride, %r1
 	ldw		R%dcache_stride(%r1), %r23
 	ldo		-1(%r23), %r21
@@ -1126,16 +1031,9 @@ ENTRY_CFI(purge_kernel_dcache_range_asm)
 	syncdma
 	bv		%r0(%r2)
 	nop
-	.exit
-
-	.procend
 ENDPROC_CFI(purge_kernel_dcache_range_asm)
 
 ENTRY_CFI(flush_user_icache_range_asm)
-	.proc
-	.callinfo NO_CALLS
-	.entry
-
 	ldil		L%icache_stride, %r1
 	ldw		R%icache_stride(%r1), %r23
 	ldo		-1(%r23), %r21
@@ -1147,16 +1045,9 @@ ENTRY_CFI(flush_user_icache_range_asm)
 	sync
 	bv		%r0(%r2)
 	nop
-	.exit
-
-	.procend
 ENDPROC_CFI(flush_user_icache_range_asm)
 
 ENTRY_CFI(flush_kernel_icache_page)
-	.proc
-	.callinfo NO_CALLS
-	.entry
-
 	ldil		L%icache_stride, %r1
 	ldw		R%icache_stride(%r1), %r23
 
@@ -1190,16 +1081,9 @@ ENTRY_CFI(flush_kernel_icache_page)
 	sync
 	bv		%r0(%r2)
 	nop
-	.exit
-
-	.procend
 ENDPROC_CFI(flush_kernel_icache_page)
 
 ENTRY_CFI(flush_kernel_icache_range_asm)
-	.proc
-	.callinfo NO_CALLS
-	.entry
-
 	ldil		L%icache_stride, %r1
 	ldw		R%icache_stride(%r1), %r23
 	ldo		-1(%r23), %r21
@@ -1211,8 +1095,6 @@ ENTRY_CFI(flush_kernel_icache_range_asm)
 	sync
 	bv		%r0(%r2)
 	nop
-	.exit
-	.procend
 ENDPROC_CFI(flush_kernel_icache_range_asm)
 
 	__INIT
@@ -1222,10 +1104,6 @@ ENDPROC_CFI(flush_kernel_icache_range_asm)
 	 */
 	.align	256
 ENTRY_CFI(disable_sr_hashing_asm)
-	.proc
-	.callinfo NO_CALLS
-	.entry
-
 	/*
 	 * Switch to real mode
 	 */
@@ -1307,9 +1185,6 @@ srdis_done:
 
 2:      bv		%r0(%r2)
 	nop
-	.exit
-
-	.procend
 ENDPROC_CFI(disable_sr_hashing_asm)
 
 	.end
diff --git a/arch/parisc/kernel/process.c b/arch/parisc/kernel/process.c
index b931745815e0..eb39e7e380d7 100644
--- a/arch/parisc/kernel/process.c
+++ b/arch/parisc/kernel/process.c
@@ -302,7 +302,7 @@ get_wchan(struct task_struct *p)
 		ip = info.ip;
 		if (!in_sched_functions(ip))
 			return ip;
-	} while (count++ < 16);
+	} while (count++ < MAX_UNWIND_ENTRIES);
 	return 0;
 }
 
diff --git a/arch/parisc/kernel/real2.S b/arch/parisc/kernel/real2.S
index cc9963421a19..2b16d8d6598f 100644
--- a/arch/parisc/kernel/real2.S
+++ b/arch/parisc/kernel/real2.S
@@ -35,12 +35,6 @@ real32_stack:
 real64_stack:
 	.block	8192
 
-#ifdef CONFIG_64BIT
-#  define REG_SZ 8
-#else
-#  define REG_SZ 4
-#endif
-
 #define N_SAVED_REGS 9
 
 save_cr_space:
diff --git a/arch/parisc/kernel/traps.c b/arch/parisc/kernel/traps.c
index 4309ad31a874..318815212518 100644
--- a/arch/parisc/kernel/traps.c
+++ b/arch/parisc/kernel/traps.c
@@ -172,7 +172,7 @@ static void do_show_stack(struct unwind_frame_info *info)
 	int i = 1;
 
 	printk(KERN_CRIT "Backtrace:\n");
-	while (i <= 16) {
+	while (i <= MAX_UNWIND_ENTRIES) {
 		if (unwind_once(info) < 0 || info->ip == 0)
 			break;
 
diff --git a/arch/parisc/kernel/unwind.c b/arch/parisc/kernel/unwind.c
index 2ef83d78eec4..7c662f770bd5 100644
--- a/arch/parisc/kernel/unwind.c
+++ b/arch/parisc/kernel/unwind.c
@@ -13,7 +13,6 @@
 #include <linux/init.h>
 #include <linux/sched.h>
 #include <linux/slab.h>
-#include <linux/kallsyms.h>
 #include <linux/sort.h>
 
 #include <linux/uaccess.h>
@@ -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
diff --git a/arch/parisc/lib/lusercopy.S b/arch/parisc/lib/lusercopy.S
index d4fe19806d57..b53fb6fedf06 100644
--- a/arch/parisc/lib/lusercopy.S
+++ b/arch/parisc/lib/lusercopy.S
@@ -64,9 +64,6 @@
 	 */
 
 ENTRY_CFI(lclear_user)
-	.proc
-	.callinfo NO_CALLS
-	.entry
 	comib,=,n   0,%r25,$lclu_done
 	get_sr
 $lclu_loop:
@@ -81,13 +78,9 @@ $lclu_done:
 	ldo         1(%r25),%r25
 
 	ASM_EXCEPTIONTABLE_ENTRY(1b,2b)
-
-	.exit
 ENDPROC_CFI(lclear_user)
 
 
-	.procend
-
 	/*
 	 * long lstrnlen_user(char *s, long n)
 	 *
@@ -97,9 +90,6 @@ ENDPROC_CFI(lclear_user)
 	 */
 
 ENTRY_CFI(lstrnlen_user)
-	.proc
-	.callinfo NO_CALLS
-	.entry
 	comib,=     0,%r25,$lslen_nzero
 	copy	    %r26,%r24
 	get_sr
@@ -111,7 +101,6 @@ $lslen_loop:
 $lslen_done:
 	bv          %r0(%r2)
 	sub	    %r26,%r24,%r28
-	.exit
 
 $lslen_nzero:
 	b           $lslen_done
@@ -125,9 +114,6 @@ $lslen_nzero:
 
 ENDPROC_CFI(lstrnlen_user)
 
-	.procend
-
-
 
 /*
  * unsigned long pa_memcpy(void *dstp, const void *srcp, unsigned long len)
@@ -186,10 +172,6 @@ ENDPROC_CFI(lstrnlen_user)
 	save_len = r31
 
 ENTRY_CFI(pa_memcpy)
-	.proc
-	.callinfo NO_CALLS
-	.entry
-
 	/* Last destination address */
 	add	dst,len,end
 
@@ -439,9 +421,6 @@ ENTRY_CFI(pa_memcpy)
 	b	.Lcopy_done
 10:	stw,ma	t1,4(dstspc,dst)
 	ASM_EXCEPTIONTABLE_ENTRY(10b,.Lcopy_done)
-
-	.exit
 ENDPROC_CFI(pa_memcpy)
-	.procend
 
 	.end
--
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