[Xen-devel] [PATCH v2 1/6] lib: Add a generic implementation of current_text_addr()

[Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>]

Remove the unused x86 implementation.

Signed-off-by: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
---

Changes in v2:
* Include Clang in the comment.

 xen/common/lib.c                | 12 ++++++++++++
 xen/include/asm-x86/processor.h | 10 ----------
 xen/include/xen/lib.h           |  2 ++
 3 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/xen/common/lib.c b/xen/common/lib.c
index 6233020..7674d3a 100644
--- a/xen/common/lib.c
+++ b/xen/common/lib.c
@@ -501,6 +501,18 @@ void __init init_constructors(void)
 }
 
 /*
+ * The GCC and Clang docs state that the function must be marked noinline to
+ * have the expected result. From the GCC docs:
+ * "When inlining the expected behavior is that the function returns the
+ * address of the function that is returned to. To work around this behavior
+ * use the noinline function attribute."
+ */
+noinline void *current_text_addr(void)
+{
+    return __builtin_return_address(0);
+}
+
+/*
  * Local variables:
  * mode: C
  * c-file-style: "BSD"
diff --git a/xen/include/asm-x86/processor.h b/xen/include/asm-x86/processor.h
index dda8b83..f9de357 100644
--- a/xen/include/asm-x86/processor.h
+++ b/xen/include/asm-x86/processor.h
@@ -98,16 +98,6 @@
 struct domain;
 struct vcpu;
 
-/*
- * Default implementation of macro that returns current
- * instruction pointer ("program counter").
- */
-#define current_text_addr() ({                      \
-    void *pc;                                       \
-    asm ( "leaq 1f(%%rip),%0\n1:" : "=r" (pc) );    \
-    pc;                                             \
-})
-
 struct x86_cpu_id {
     uint16_t vendor;
     uint16_t family;
diff --git a/xen/include/xen/lib.h b/xen/include/xen/lib.h
index 995a85a..6b4f1e4 100644
--- a/xen/include/xen/lib.h
+++ b/xen/include/xen/lib.h
@@ -162,6 +162,8 @@ extern void add_taint(unsigned int taint);
 struct cpu_user_regs;
 void dump_execstate(struct cpu_user_regs *);
 
+void *current_text_addr(void);
+
 void init_constructors(void);
 
 void *bsearch(const void *key, const void *base, size_t num, size_t size,
-- 
2.7.4


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