[Xen-devel] [PATCH livepatch-expect 1/2] create-diff-object: Add support for expectations

[Pawel Wieczorkiewicz <wipawel@xxxxxxxxx>]

Extend livepatch_patch_func to support a new field: expect. This new
field describes the expected data, its length and whether expectation
is enabled. The expectation's data is of opaque padding size.

Bump the payload version for hotpatches built with expectations.
The expectations are supported starting from version 3 of the payload.

By default the expectation field is zero-out and the expectation is
disabled unless explicitly specified in the patch.

Signed-off-by: Pawel Wieczorkiewicz <wipawel@xxxxxxxxx>
---
 common.h             | 11 ++++++++++-
 create-diff-object.c |  3 ++-
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/common.h b/common.h
index d8cde35..7c6fb73 100644
--- a/common.h
+++ b/common.h
@@ -115,6 +115,14 @@ struct kpatch_elf {
 };
 
 #define PATCH_INSN_SIZE 5
+#define MAX_REPLACEMENT_SIZE 31
+struct livepatch_expectation {
+       uint8_t enabled : 1;
+       uint8_t len : 5;
+       uint8_t pad : 2;
+       uint8_t data[MAX_REPLACEMENT_SIZE];
+};
+typedef struct livepatch_expectation livepatch_expectation_t;
 
 struct livepatch_patch_func {
        char *name;
@@ -123,9 +131,10 @@ struct livepatch_patch_func {
        uint32_t new_size;
        uint32_t old_size;
        uint8_t version;
-       unsigned char pad[31];
+       unsigned char pad[MAX_REPLACEMENT_SIZE];
        uint8_t applied;
        uint8_t _pad[7];
+       livepatch_expectation_t expect;
 };
 
 struct special_section {
diff --git a/create-diff-object.c b/create-diff-object.c
index 534516b..c7431cc 100644
--- a/create-diff-object.c
+++ b/create-diff-object.c
@@ -2009,10 +2009,11 @@ static void livepatch_create_patches_sections(struct 
kpatch_elf *kelf,
                        funcs[index].old_size = result.size;
                        funcs[index].new_addr = 0;
                        funcs[index].new_size = sym->sym.st_size;
-                       funcs[index].version = 2;
+                       funcs[index].version = 3;
                        memset(funcs[index].pad, 0, sizeof funcs[index].pad);
                        funcs[index].applied = 0;
                        memset(funcs[index]._pad, 0, sizeof funcs[index]._pad);
+                       memset(&funcs[index].expect, 0, sizeof 
funcs[index].expect);
 
                        /*
                         * Add a relocation that will populate
-- 
2.16.5




Amazon Development Center Germany GmbH
Krausenstr. 38
10117 Berlin
Geschaeftsfuehrung: Christian Schlaeger, Ralf Herbrich
Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B
Sitz: Berlin
Ust-ID: DE 289 237 879




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