Re: [Xen-devel] [PATCH v2 08/12] livepatch: Add support for inline asm hotpatching expectations

["Wieczorkiewicz, Pawel" <wipawel@xxxxxxxxx>]

On 29. Aug 2019, at 16:34, Konrad Rzeszutek Wilk <konrad@xxxxxxxxxx> wrote:

…snip...

+
+struct livepatch_func __section(".livepatch.funcs") livepatch_exceptions = {
+    .version = LIVEPATCH_PAYLOAD_VERSION,
+    .name = livepatch_exceptions_str,
+    .new_addr = xen_hello_world,
+    .old_addr = xen_extra_version,
+    .new_size = EXPECT_BYTES_COUNT,
+    .old_size = EXPECT_BYTES_COUNT,
+    .expect = {
+        .enabled = 1,
+        .len = EXPECT_BYTES_COUNT,
+        .data = "" class=""> +    },
+
+};

When I compile with 32-bit ARM 'make tests' I get:

arm-eabi-ld    -EL -EL     --build-id=sha1 -r -o xen_action_hooks_norevert.livepatch xen_action_hooks_marker.o xen_hello_world_func.o note.o xen_note.o
make[3]: Circular expect_config.h <- xen_expectations.o dependency dropped.
objdump: can't disassemble for architecture UNKNOWN!

(set -e; \
echo "#define EXPECT_BYTES {"; \
        echo "#define EXPECT_BYTES_COUNT 6") > expect_config.h
arm-eabi-gcc -marm -DBUILD_ID -fno-strict-aliasing -std=gnu99 -Wall -Wstrict-prototypes -Wdeclaration-after-statement -Wno-unused-but-set-variable -Wno-unused-local-typedefs   -O1 -fno-omit-frame-pointer -nostdinc -fno-builtin -fno-common -Werror -Wredundant-decls -Wno-pointer-arith -Wvla -pipe -D__XEN__ -include /home/konrad/A20/xen.git/xen/include/xen/config.h '-D__OBJECT_FILE__="xen_expectations.o"' -Wa,--strip-local-absolute -g -MMD -MF ./.xen_expectations.o.d -msoft-float -mcpu=cortex-a15 -DCONFIG_EARLY_PRINTK -DEARLY_PRINTK_INC=\"debug-8250.inc\" -DEARLY_PRINTK_BAUD= -DEARLY_UART_BASE_ADDRESS=0x01c28000 -DEARLY_UART_REG_SHIFT=2  -I/home/konrad/A20/xen.git/xen/include -fno-stack-protector -fno-exceptions -Wnested-externs -DGCC_HAS_VISIBILITY_ATTRIBUTE -marm -DBUILD_ID -fno-strict-aliasing -std=gnu99 -Wall -Wstrict-prototypes -Wdeclaration-after-statement -Wno-unused-but-set-variable -Wno-unused-local-typedefs   -c xen_expectations.c -o xen_expectations.o
xen_expectations.c:31:2: error: expected '}' before ';' token
};
 ^
xen_expectations.c:18:76: note: to match this '{'
struct livepatch_func __section(".livepatch.funcs") livepatch_exceptions = {
                                                                           ^
make[3]: *** [/home/konrad/A20/xen.git/xen/Rules.mk:202: xen_expectations.o] Error 1
make[3]: Leaving directory '/home/konrad/A20/xen.git/xen/test/livepatch'


And this is what expect_config.h looks like:

#define EXPECT_BYTES {
#define EXPECT_BYTES_COUNT 6

Hi Konrad,

I think I fixed it with the following change on top:

[DIFF START]

diff --git a/xen/test/livepatch/Makefile b/xen/test/livepatch/Makefile

index 067861903f..20bdeb6c6d 100644

--- a/xen/test/livepatch/Makefile

+++ b/xen/test/livepatch/Makefile

@@ -186,10 +186,17 @@ xen_actions_hooks_norevert.o: config.h

 $(LIVEPATCH_ACTION_HOOKS_NOREVERT): xen_action_hooks_marker.o xen_hello_world_func.o note.o xen_note.o

        $(LD) $(LDFLAGS) $(build_id_linker) -r -o $(LIVEPATCH_ACTION_HOOKS_NOREVERT) $^

-CODE_GET_EXPECT=$(shell objdump -d --insn-width=1 $(1) | grep -A6 -E '<'$(2)'>:' | tail -n +2 | awk 'BEGIN {printf "{"} {printf "0x%s,", $$2}' | sed 's/,$$/}/g')

+ifeq ($(findstring arm, $(TARGET_ARCH) $(ARCH)),arm)

+INSN_WIDTH := 4

+INSN_PER_LINE := 2

+else

+INSN_WIDTH := 1

+INSN_PER_LINE := 8

+endif

+CODE_GET_EXPECT=$(shell $(OBJDUMP) -d --insn-width=$(INSN_WIDTH) $(1) | sed -n -e '/<'$(2)'>:$$/,/^$$/ p' | tail -n +2 | head -n $(INSN_PER_LINE) | awk '{printf "%s", $$2}' | sed 's/.\{2\}/0x&,/g' | sed 's/^/{/;s/,$$/}/g')

 .PHONY: expect_config.h

 expect_config.h: EXPECT_BYTES=$(call CODE_GET_EXPECT,$(BASEDIR)/xen-syms,xen_extra_version)

-expect_config.h: EXPECT_BYTES_COUNT=6

+expect_config.h: EXPECT_BYTES_COUNT=8

 expect_config.h: xen_expectations.o

        (set -e; \

         echo "#define EXPECT_BYTES $(EXPECT_BYTES)"; \

[DIFF END]

I will test that some more and add it to the v3 of the patchset.

Best Regards,
Pawel Wieczorkiewicz

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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