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Wed, 23 Nov 2022 13:07:39 +0000 (GMT) Received: from p-imbrenda (unknown [9.152.224.56]) by b06wcsmtp001.portsmouth.uk.ibm.com (Postfix) with ESMTP; Wed, 23 Nov 2022 13:07:39 +0000 (GMT) Date: Wed, 23 Nov 2022 13:45:23 +0100 From: Claudio Imbrenda To: Janosch Frank Cc: kvm@vger.kernel.org, linux-s390@vger.kernel.org, david@redhat.com, thuth@redhat.com, seiden@linux.ibm.com, nrb@linux.ibm.com Subject: Re: [kvm-unit-tests PATCH 1/5] s390x: Add a linker script to assembly snippets Message-ID: <20221123134523.5af2b5ab@p-imbrenda> In-Reply-To: <20221123084656.19864-2-frankja@linux.ibm.com> References: <20221123084656.19864-1-frankja@linux.ibm.com> <20221123084656.19864-2-frankja@linux.ibm.com> Organization: IBM X-Mailer: Claws Mail 4.1.1 (GTK 3.24.34; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: VHIUI7TdKQkhLKLvbua2QUQ0hhxUmAei X-Proofpoint-ORIG-GUID: f8OAfI_T4QmobjKf8GLoY6gS5b7_MGrP X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.219,Aquarius:18.0.895,Hydra:6.0.545,FMLib:17.11.122.1 definitions=2022-11-23_06,2022-11-23_01,2022-06-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxscore=0 phishscore=0 adultscore=0 spamscore=0 impostorscore=0 clxscore=1015 bulkscore=0 malwarescore=0 suspectscore=0 lowpriorityscore=0 mlxlogscore=999 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2210170000 definitions=main-2211230097 Precedence: bulk List-ID: X-Mailing-List: linux-s390@vger.kernel.org On Wed, 23 Nov 2022 08:46:52 +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 looks good in general, but I have a few questions > --- > 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 > > > /* > 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 $(patsubst %.gbin,%.o,$@) I think you can simply use $< instead of the patsubst expression > + $(OBJCOPY) -O binary -j ".rodata" -j ".lowcore" -j ".text" -j ".data" -j ".bss" --set-section-flags .bss=alloc,load,contents $@ $@ > 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/mvpg-sie.c b/s390x/mvpg-sie.c > index 46a2edb6..99f4859b 100644 > --- a/s390x/mvpg-sie.c > +++ b/s390x/mvpg-sie.c > @@ -87,7 +87,7 @@ static void setup_guest(void) > > snippet_setup_guest(&vm, false); > snippet_init(&vm, SNIPPET_NAME_START(c, mvpg_snippet), > - SNIPPET_LEN(c, mvpg_snippet), SNIPPET_OFF_C); > + SNIPPET_LEN(c, mvpg_snippet), SNIPPET_UNPACK_OFF); > > /* Enable MVPG interpretation as we want to test KVM and not ourselves */ > vm.sblk->eca = ECA_MVPGI; > diff --git a/s390x/pv-diags.c b/s390x/pv-diags.c > index 9ced68c7..5165937a 100644 > --- a/s390x/pv-diags.c > +++ b/s390x/pv-diags.c > @@ -28,7 +28,7 @@ static void test_diag_500(void) > > snippet_pv_init(&vm, SNIPPET_NAME_START(asm, snippet_pv_diag_500), > SNIPPET_HDR_START(asm, snippet_pv_diag_500), > - size_gbin, size_hdr, SNIPPET_OFF_ASM); > + size_gbin, size_hdr, SNIPPET_UNPACK_OFF); > > sie(&vm); > report(vm.sblk->icptcode == ICPT_PV_INSTR && vm.sblk->ipa == 0x8302 && > @@ -83,7 +83,7 @@ static void test_diag_288(void) > > snippet_pv_init(&vm, SNIPPET_NAME_START(asm, snippet_pv_diag_288), > SNIPPET_HDR_START(asm, snippet_pv_diag_288), > - size_gbin, size_hdr, SNIPPET_OFF_ASM); > + size_gbin, size_hdr, SNIPPET_UNPACK_OFF); > > sie(&vm); > report(vm.sblk->icptcode == ICPT_PV_INSTR && vm.sblk->ipa == 0x8302 && > @@ -124,7 +124,7 @@ static void test_diag_yield(void) > > snippet_pv_init(&vm, SNIPPET_NAME_START(asm, snippet_pv_diag_yield), > SNIPPET_HDR_START(asm, snippet_pv_diag_yield), > - size_gbin, size_hdr, SNIPPET_OFF_ASM); > + size_gbin, size_hdr, SNIPPET_UNPACK_OFF); > > /* 0x44 */ > report_prefix_push("0x44"); > 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); any reason to align to 64k? (instead of e.g. 4k) > + etext = .; > + . = ALIGN(16); do you need the ALIGN? I would think we are already aligned here > + .data : { > + *(.data) > + *(.data.rel*) > + } > + . = ALIGN(16); > + .rodata : { *(.rodata) *(.rodata.*) } > + . = ALIGN(16); > + __bss_start = .; > + .bss : { *(.bss) } > + __bss_end = .; > + . = ALIGN(64K); same question as above regarding 64k > +}