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Re: [Xen-devel] [PATCH v1 3/9] x86/arm64: Move the ALT_[ORIG|REPL]_PTR macros to header files.



Hi Konrad,

On 15/08/16 00:07, Konrad Rzeszutek Wilk wrote:
That way common code can use the same macro to access
the most common attributes without much #ifdef.

Take advantage of it right away in the livepatch code.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>

---
Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
Cc: Julien Grall <julien.grall@xxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

v1: First submission
---
 xen/arch/arm/alternative.c        | 4 ----
 xen/common/livepatch.c            | 4 ++--
 xen/include/asm-arm/alternative.h | 4 ++++
 xen/include/asm-x86/alternative.h | 4 ++++
 4 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/xen/arch/arm/alternative.c b/xen/arch/arm/alternative.c
index 8ee5a11..bf4101c 100644
--- a/xen/arch/arm/alternative.c
+++ b/xen/arch/arm/alternative.c
@@ -32,10 +32,6 @@
 #include <asm/insn.h>
 #include <asm/page.h>

-#define __ALT_PTR(a,f)      (u32 *)((void *)&(a)->f + (a)->f)
-#define ALT_ORIG_PTR(a)     __ALT_PTR(a, orig_offset)
-#define ALT_REPL_PTR(a)     __ALT_PTR(a, alt_offset)
-
 extern const struct alt_instr __alt_instructions[], __alt_instructions_end[];

 struct alt_region {
diff --git a/xen/common/livepatch.c b/xen/common/livepatch.c
index 3a22de2..9c45270 100644
--- a/xen/common/livepatch.c
+++ b/xen/common/livepatch.c
@@ -700,8 +700,8 @@ static int prepare_payload(struct payload *payload,

         for ( a = start; a < end; a++ )
         {
-            const void *instr = &a->instr_offset + a->instr_offset;
-            const void *replacement = &a->repl_offset + a->repl_offset;
+            const void *instr = ALT_ORIG_PTR(a);
+            const void *replacement = ALT_REPL_PTR(a);

             if ( (instr < region->start && instr >= region->end) ||
                  (replacement < region->start && replacement >= region->end) )
diff --git a/xen/include/asm-arm/alternative.h 
b/xen/include/asm-arm/alternative.h
index 4287bac..58d5fa7 100644
--- a/xen/include/asm-arm/alternative.h
+++ b/xen/include/asm-arm/alternative.h
@@ -21,6 +21,10 @@ struct alt_instr {
        u8  alt_len;            /* size of new instruction(s), <= orig_len */
 };

+#define __ALT_PTR(a,f)      (u32 *)((void *)&(a)->f + (a)->f)
+#define ALT_ORIG_PTR(a)     __ALT_PTR(a, orig_offset)
+#define ALT_REPL_PTR(a)     __ALT_PTR(a, alt_offset)
+

alternative.h is a verbatim copy of the Linux one. So can you add a comment such as /* Xen: helpers used by the common code */?

Also this should be indented with hard tab as the file is following the Linux coding style.

 void __init apply_alternatives_all(void);
 int apply_alternatives(void *start, size_t length);

diff --git a/xen/include/asm-x86/alternative.h 
b/xen/include/asm-x86/alternative.h
index acaeded..b72c401 100644
--- a/xen/include/asm-x86/alternative.h
+++ b/xen/include/asm-x86/alternative.h
@@ -23,6 +23,10 @@ struct alt_instr {
     u8  replacementlen;     /* length of new instruction, <= instrlen */
 };

+#define __ALT_PTR(a,f)      (u8 *)((void *)&(a)->f + (a)->f)
+#define ALT_ORIG_PTR(a)     __ALT_PTR(a, instr_offset)
+#define ALT_REPL_PTR(a)     __ALT_PTR(a, repl_offset)
+
 extern void add_nops(void *insns, unsigned int len);
 /* Similar to apply_alternatives except it can be run with IRQs enabled. */
 extern void apply_alternatives_nocheck(struct alt_instr *start,


Regards,

--
Julien Grall

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