From 526869b757f8855bb193aa6a3950c3216bc92c84 Mon Sep 17 00:00:00 2001
From: Nick Alcock <nick.alcock@oracle.com>
Date: Fri, 29 Jan 2016 15:04:40 +0000
Subject: [PATCH] dtrace: apply stack bias to user stack walks on SPARC

We were walking the stack without applying the stack bias, leading to a
big chunk of the start of the stack being cut off (often all of it).

Orabug: 22629102
Signed-off-by: Nick Alcock <nick.alcock@oracle.com>
Acked-by: Kris Van Hees <kris.van.hees@oracle.com>
---
 dtrace/dtrace_isa.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/dtrace/dtrace_isa.c b/dtrace/dtrace_isa.c
index f107b425d924..8b5e8c40ccb6 100644
--- a/dtrace/dtrace_isa.c
+++ b/dtrace/dtrace_isa.c
@@ -31,6 +31,7 @@
 #include <linux/smp.h>
 #include <linux/uaccess.h>
 #include <asm/cacheflush.h>
+#include <asm/ptrace.h>
 #include <asm/stacktrace.h>
 
 #include "dtrace.h"
@@ -232,8 +233,10 @@ unsigned long dtrace_getufpstack(uint64_t *pcstack, uint64_t *fpstack,
 
 #ifdef CONFIG_X86_64
 	tos = current_user_stack_pointer();
+#elif defined(STACK_BIAS)
+	tos = user_stack_pointer(current_pt_regs()) + STACK_BIAS;
 #else
-	tos = user_stack_pointer(current_pt_regs());
+#error Not x86-64 nor a stack-biased platform, porting needed
 #endif
 	stack_vma = find_user_vma(p, mm, NULL, (unsigned long) tos, 0);
 	if (!stack_vma ||
-- 
2.50.1