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Fri, 25 Nov 2022 10:07:12 +0000 (GMT) Received: from [9.171.63.115] (unknown [9.171.63.115]) by d06av24.portsmouth.uk.ibm.com (Postfix) with ESMTP; Fri, 25 Nov 2022 10:07:12 +0000 (GMT) Message-ID: <76c9dbfe-a570-667d-37e9-8d1bc710b58f@linux.ibm.com> Date: Fri, 25 Nov 2022 11:07:12 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.5.0 Subject: Re: [kvm-unit-tests PATCH 1/5] s390x: Add a linker script to assembly snippets To: Janis Schoetterl-Glausch , kvm@vger.kernel.org Cc: linux-s390@vger.kernel.org, imbrenda@linux.ibm.com, david@redhat.com, thuth@redhat.com, seiden@linux.ibm.com, nrb@linux.ibm.com References: <20221123084656.19864-1-frankja@linux.ibm.com> <20221123084656.19864-2-frankja@linux.ibm.com> <2803564dcc325f716548ea3a8938d8c0b7814a33.camel@linux.ibm.com> Content-Language: en-US From: Janosch Frank In-Reply-To: <2803564dcc325f716548ea3a8938d8c0b7814a33.camel@linux.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: WDqXyYpPlPBeT5k9cE5DMl3jqri6SSXD X-Proofpoint-GUID: Vv9oImV2gUlE0MketFukBJYxydeT9vq6 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=2022-11-25_02,2022-11-25_01,2022-06-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 lowpriorityscore=0 suspectscore=0 mlxscore=0 phishscore=0 malwarescore=0 adultscore=0 clxscore=1015 mlxlogscore=999 spamscore=0 impostorscore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2210170000 definitions=main-2211250075 Precedence: bulk List-ID: X-Mailing-List: linux-s390@vger.kernel.org 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 >> --- >> 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); >> +} >