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(unknown [9.114.12.104]) by d06av25.portsmouth.uk.ibm.com (Postfix) with ESMTP; Thu, 7 Apr 2022 09:48:29 +0000 (GMT) From: Janosch Frank To: qemu-devel@nongnu.org Subject: [PATCH v4] dump: Remove the sh_info variable Date: Thu, 7 Apr 2022 09:48:24 +0000 Message-Id: <20220407094824.5074-1-frankja@linux.ibm.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: References: MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: pwxRTkVLYwMg_GUtiFog5Z4HKXeIW4zJ X-Proofpoint-GUID: mp2Q2zT1vWntKq3Oj6Lg91PCKjAn7hGh X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.850,Hydra:6.0.425,FMLib:17.11.64.514 definitions=2022-04-06_13,2022-04-06_01,2022-02-23_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 mlxscore=0 mlxlogscore=999 lowpriorityscore=0 phishscore=0 priorityscore=1501 impostorscore=0 suspectscore=0 clxscore=1015 adultscore=0 malwarescore=0 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2202240000 definitions=main-2204070048 Received-SPF: pass client-ip=148.163.158.5; envelope-from=frankja@linux.ibm.com; helo=mx0b-001b2d01.pphosted.com X-Spam_score_int: -19 X-Spam_score: -2.0 X-Spam_bar: -- X-Spam_report: (-2.0 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: pbonzini@redhat.com, richard.henderson@linaro.org, marcandre.lureau@gmail.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" There's no need to have phdr_num and sh_info at the same time. We can make phdr_num 32 bit and set PN_XNUM when we write the header if phdr_num >= PN_XNUM. Signed-off-by: Janosch Frank Reviewed-by: Richard Henderson --- A question out of general curiosity: Is PN_XNUM a real concern anyway? Are architectures using >65k segments in real life? * Uses MIN() * Added explanation for the PN_XNUM usage --- dump/dump.c | 44 +++++++++++++++++++++++-------------------- include/sysemu/dump.h | 3 +-- 2 files changed, 25 insertions(+), 22 deletions(-) diff --git a/dump/dump.c b/dump/dump.c index 58c4923fce..56cd1b2bb8 100644 --- a/dump/dump.c +++ b/dump/dump.c @@ -124,6 +124,12 @@ static int fd_write_vmcore(const void *buf, size_t size, void *opaque) static void write_elf64_header(DumpState *s, Error **errp) { + /* + * phnum in the elf header is 16 bit, if we have more segments we + * set phnum to PN_XNUM and write the real number of segments to a + * special section. + */ + uint16_t phnum = MIN(s->phdr_num, PN_XNUM); Elf64_Ehdr elf_header; int ret; @@ -138,9 +144,9 @@ static void write_elf64_header(DumpState *s, Error **errp) elf_header.e_ehsize = cpu_to_dump16(s, sizeof(elf_header)); elf_header.e_phoff = cpu_to_dump64(s, sizeof(Elf64_Ehdr)); elf_header.e_phentsize = cpu_to_dump16(s, sizeof(Elf64_Phdr)); - elf_header.e_phnum = cpu_to_dump16(s, s->phdr_num); + elf_header.e_phnum = cpu_to_dump16(s, phnum); if (s->have_section) { - uint64_t shoff = sizeof(Elf64_Ehdr) + sizeof(Elf64_Phdr) * s->sh_info; + uint64_t shoff = sizeof(Elf64_Ehdr) + sizeof(Elf64_Phdr) * s->phdr_num; elf_header.e_shoff = cpu_to_dump64(s, shoff); elf_header.e_shentsize = cpu_to_dump16(s, sizeof(Elf64_Shdr)); @@ -155,6 +161,12 @@ static void write_elf64_header(DumpState *s, Error **errp) static void write_elf32_header(DumpState *s, Error **errp) { + /* + * phnum in the elf header is 16 bit, if we have more segments we + * set phnum to PN_XNUM and write the real number of segments to a + * special section. + */ + uint16_t phnum = MIN(s->phdr_num, PN_XNUM); Elf32_Ehdr elf_header; int ret; @@ -169,9 +181,9 @@ static void write_elf32_header(DumpState *s, Error **errp) elf_header.e_ehsize = cpu_to_dump16(s, sizeof(elf_header)); elf_header.e_phoff = cpu_to_dump32(s, sizeof(Elf32_Ehdr)); elf_header.e_phentsize = cpu_to_dump16(s, sizeof(Elf32_Phdr)); - elf_header.e_phnum = cpu_to_dump16(s, s->phdr_num); + elf_header.e_phnum = cpu_to_dump16(s, phnum); if (s->have_section) { - uint32_t shoff = sizeof(Elf32_Ehdr) + sizeof(Elf32_Phdr) * s->sh_info; + uint32_t shoff = sizeof(Elf32_Ehdr) + sizeof(Elf32_Phdr) * s->phdr_num; elf_header.e_shoff = cpu_to_dump32(s, shoff); elf_header.e_shentsize = cpu_to_dump16(s, sizeof(Elf32_Shdr)); @@ -358,12 +370,12 @@ static void write_elf_section(DumpState *s, int type, Error **errp) if (type == 0) { shdr_size = sizeof(Elf32_Shdr); memset(&shdr32, 0, shdr_size); - shdr32.sh_info = cpu_to_dump32(s, s->sh_info); + shdr32.sh_info = cpu_to_dump32(s, s->phdr_num); shdr = &shdr32; } else { shdr_size = sizeof(Elf64_Shdr); memset(&shdr64, 0, shdr_size); - shdr64.sh_info = cpu_to_dump32(s, s->sh_info); + shdr64.sh_info = cpu_to_dump32(s, s->phdr_num); shdr = &shdr64; } @@ -478,13 +490,6 @@ static void write_elf_loads(DumpState *s, Error **errp) hwaddr offset, filesz; MemoryMapping *memory_mapping; uint32_t phdr_index = 1; - uint32_t max_index; - - if (s->have_section) { - max_index = s->sh_info; - } else { - max_index = s->phdr_num; - } QTAILQ_FOREACH(memory_mapping, &s->list.head, next) { get_offset_range(memory_mapping->phys_addr, @@ -502,7 +507,7 @@ static void write_elf_loads(DumpState *s, Error **errp) return; } - if (phdr_index >= max_index) { + if (phdr_index >= s->phdr_num) { break; } } @@ -1801,22 +1806,21 @@ static void dump_init(DumpState *s, int fd, bool has_format, s->phdr_num += s->list.num; s->have_section = false; } else { + /* sh_info of section 0 holds the real number of phdrs */ s->have_section = true; - s->phdr_num = PN_XNUM; - s->sh_info = 1; /* PT_NOTE */ /* the type of shdr->sh_info is uint32_t, so we should avoid overflow */ if (s->list.num <= UINT32_MAX - 1) { - s->sh_info += s->list.num; + s->phdr_num += s->list.num; } else { - s->sh_info = UINT32_MAX; + s->phdr_num = UINT32_MAX; } } if (s->dump_info.d_class == ELFCLASS64) { if (s->have_section) { s->memory_offset = sizeof(Elf64_Ehdr) + - sizeof(Elf64_Phdr) * s->sh_info + + sizeof(Elf64_Phdr) * s->phdr_num + sizeof(Elf64_Shdr) + s->note_size; } else { s->memory_offset = sizeof(Elf64_Ehdr) + @@ -1825,7 +1829,7 @@ static void dump_init(DumpState *s, int fd, bool has_format, } else { if (s->have_section) { s->memory_offset = sizeof(Elf32_Ehdr) + - sizeof(Elf32_Phdr) * s->sh_info + + sizeof(Elf32_Phdr) * s->phdr_num + sizeof(Elf32_Shdr) + s->note_size; } else { s->memory_offset = sizeof(Elf32_Ehdr) + diff --git a/include/sysemu/dump.h b/include/sysemu/dump.h index 250143cb5a..b463fc9c02 100644 --- a/include/sysemu/dump.h +++ b/include/sysemu/dump.h @@ -154,8 +154,7 @@ typedef struct DumpState { GuestPhysBlockList guest_phys_blocks; ArchDumpInfo dump_info; MemoryMappingList list; - uint16_t phdr_num; - uint32_t sh_info; + uint32_t phdr_num; bool have_section; bool resume; bool detached;