On 11/24/22 21:42, Janis Schoetterl-Glausch wrote:
On Wed, 2022-11-23 at 08:46 +0000, Janosch Frank wrote:
A linker script has a few benefits:
- Random data doesn't end up in the binary breaking tests
- We can easily define a lowcore and load the snippet from 0x0 instead
of 0x4000 which makes asm snippets behave like c snippets
- We can easily define an invalid PGM new PSW to ensure an exit on a
guest PGM
Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
---
lib/s390x/snippet.h | 3 +--
s390x/Makefile | 5 +++--
s390x/mvpg-sie.c | 2 +-
s390x/pv-diags.c | 6 +++---
s390x/snippets/asm/flat.lds | 43 +++++++++++++++++++++++++++++++++++++
5 files changed, 51 insertions(+), 8 deletions(-)
create mode 100644 s390x/snippets/asm/flat.lds
diff --git a/lib/s390x/snippet.h b/lib/s390x/snippet.h
index b17b2a4c..57045994 100644
--- a/lib/s390x/snippet.h
+++ b/lib/s390x/snippet.h
@@ -32,8 +32,7 @@
#define SNIPPET_PV_TWEAK0 0x42UL
#define SNIPPET_PV_TWEAK1 0UL
-#define SNIPPET_OFF_C 0
-#define SNIPPET_OFF_ASM 0x4000
+#define SNIPPET_UNPACK_OFF 0
You could also get rid of the offset parameter, couldn't you?
Right
/*
diff --git a/s390x/Makefile b/s390x/Makefile
index bf1504f9..bb0f9eb8 100644
--- a/s390x/Makefile
+++ b/s390x/Makefile
@@ -135,7 +135,8 @@ $(SNIPPET_DIR)/c/%.o: $(SNIPPET_DIR)/c/%.c $(asm-offsets)
$(CC) $(CFLAGS) -c -nostdlib -o $@ $<
$(SNIPPET_DIR)/asm/%.gbin: $(SNIPPET_DIR)/asm/%.o
- $(OBJCOPY) -O binary -j ".rodata" -j ".text" -j ".data" -j ".bss" --set-section-flags .bss=alloc,load,contents $(patsubst %.gbin,%.o,$@) $@
+ $(CC) $(LDFLAGS) -o $@ -T $(SRCDIR)/s390x/snippets/asm/flat.lds $(patsubst %.gbin,%.o,$@)
+ $(OBJCOPY) -O binary -j ".rodata" -j ".lowcore" -j ".text" -j ".data" -j ".bss" --set-section-flags .bss=alloc,load,contents $@ $@
I assume .bss=alloc allocates the bss in the binary...
And that's fine since I don't want to handle 0x3E PGMs/faults.
If bss is in the binary then it'll be made secure on initial image
unpack, if it isn't, then we need a handler to import pages on a 0x3E.
And I don't really want to do that since a 0x3E could also mean that we
have an issue with the test or HW/FW.
truncate -s '%4096' $@
$(SNIPPET_DIR)/c/%.gbin: $(SNIPPET_DIR)/c/%.o $(snippet_lib) $(FLATLIBS)
@@ -144,7 +145,7 @@ $(SNIPPET_DIR)/c/%.gbin: $(SNIPPET_DIR)/c/%.o $(snippet_lib) $(FLATLIBS)
truncate -s '%4096' $@
$(SNIPPET_DIR)/asm/%.hdr: $(SNIPPET_DIR)/asm/%.gbin $(HOST_KEY_DOCUMENT)
- $(GEN_SE_HEADER) -k $(HOST_KEY_DOCUMENT) -c $<,0x4000,0x00000000000000420000000000000000 --psw-addr 0x4000 -o $@
+ $(GEN_SE_HEADER) -k $(HOST_KEY_DOCUMENT) -c $<,0x0,0x00000000000000420000000000000000 --psw-addr 0x4000 -o $@
$(SNIPPET_DIR)/c/%.hdr: $(SNIPPET_DIR)/c/%.gbin $(HOST_KEY_DOCUMENT)
$(GEN_SE_HEADER) -k $(HOST_KEY_DOCUMENT) -c $<,0x0,0x00000000000000420000000000000000 --psw-addr 0x4000 -o $@
[...]
diff --git a/s390x/snippets/asm/flat.lds b/s390x/snippets/asm/flat.lds
new file mode 100644
index 00000000..366d2d78
--- /dev/null
+++ b/s390x/snippets/asm/flat.lds
@@ -0,0 +1,43 @@
+SECTIONS
+{
+ .lowcore : {
+ /*
+ * Initial short psw for disk boot, with 31 bit addressing for
+ * non z/Arch environment compatibility and the instruction
+ * address 0x4000.
+ */
+ . = 0;
+ LONG(0x00080000)
+ LONG(0x80004000)
+ /* Restart new PSW for booting via PSW restart. */
+ . = 0x1a0;
+ QUAD(0x0000000180000000)
+ QUAD(0x0000000000004000)
+ /*
+ * Invalid PGM new PSW so we hopefully get a code 8
+ * intercept on a PGM
+ */
+ . = 0x1d0;
+ QUAD(0x0008000000000000)
+ QUAD(0x0000000000000001)
+ }
+ . = 0x4000;
+ .text : {
+ *(.text)
+ *(.text.*)
+ }
+ . = ALIGN(64K);
+ etext = .;
+ . = ALIGN(16);
+ .data : {
+ *(.data)
+ *(.data.rel*)
+ }
+ . = ALIGN(16);
+ .rodata : { *(.rodata) *(.rodata.*) }
+ . = ALIGN(16);
+ __bss_start = .;
.. so the __bss symbols are not necessary.
But then, the c flat.lds has them too.
+ .bss : { *(.bss) }
+ __bss_end = .;
+ . = ALIGN(64K);
+}
