[v2,5/7] create-diff-object: Add support for expectations

Commit Message

Wieczorkiewicz, Pawel Sept. 16, 2019, 11:30 a.m. UTC

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.

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

Signed-off-by: Pawel Wieczorkiewicz <[e-mail]>
---
Changed since v1:
  * Do not bump the payload version again.

 common.h             | 11 ++++++++++-
 create-diff-object.c |  1 +
 2 files changed, 11 insertions(+), 1 deletion(-)

Comments

Ross Lagerwall Nov. 25, 2019, 2:22 p.m. UTC | #1

On 9/16/19 12:30 PM, Pawel Wieczorkiewicz wrote:
> 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.
> 
> By default the expectation field is zero-out and the expectation is
> disabled unless explicitly specified in the patch.
> 
> Signed-off-by: Pawel Wieczorkiewicz <[e-mail]>
Reviewed-by: Ross Lagerwall <[e-mail]>

Patch

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 d518503..e4592a6 100644
--- a/create-diff-object.c
+++ b/create-diff-object.c
@@ -2018,6 +2018,7 @@  static void livepatch_create_patches_sections(struct kpatch_elf *kelf,
 			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