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151 lines
4.9 KiB
151 lines
4.9 KiB
From a918c7305ec7c68e8bc37b449f71e75d84124cd0 Mon Sep 17 00:00:00 2001
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From: Janosch Frank <frankja@linux.ibm.com>
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Date: Mon, 17 Oct 2022 08:38:13 +0000
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Subject: [PATCH 32/42] dump: Use a buffer for ELF section data and headers
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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RH-Author: Cédric Le Goater <clg@redhat.com>
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RH-MergeRequest: 226: s390: Enhanced Interpretation for PCI Functions and Secure Execution guest dump
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RH-Bugzilla: 1664378 2043909
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RH-Acked-by: Thomas Huth <thuth@redhat.com>
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RH-Acked-by: Cornelia Huck <cohuck@redhat.com>
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RH-Acked-by: Jon Maloy <jmaloy@redhat.com>
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RH-Commit: [32/41] e1a03e202e67764581e486f37e13e479200e5846
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Currently we're writing the NULL section header if we overflow the
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physical header number in the ELF header. But in the future we'll add
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custom section headers AND section data.
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To facilitate this we need to rearange section handling a bit. As with
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the other ELF headers we split the code into a prepare and a write
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step.
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Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
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Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
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Message-Id: <20221017083822.43118-2-frankja@linux.ibm.com>
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(cherry picked from commit e41ed29bcee5cb16715317bcf290f6b5c196eb0a)
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Signed-off-by: Cédric Le Goater <clg@redhat.com>
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---
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dump/dump.c | 75 +++++++++++++++++++++++++++++--------------
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include/sysemu/dump.h | 2 ++
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2 files changed, 53 insertions(+), 24 deletions(-)
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diff --git a/dump/dump.c b/dump/dump.c
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index 88177fa886..4142b4cc0c 100644
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--- a/dump/dump.c
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+++ b/dump/dump.c
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@@ -381,31 +381,60 @@ static void write_elf_phdr_note(DumpState *s, Error **errp)
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}
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}
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-static void write_elf_section(DumpState *s, int type, Error **errp)
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+static void prepare_elf_section_hdr_zero(DumpState *s)
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{
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- Elf32_Shdr shdr32;
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- Elf64_Shdr shdr64;
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- int shdr_size;
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- void *shdr;
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- int ret;
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+ if (dump_is_64bit(s)) {
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+ Elf64_Shdr *shdr64 = s->elf_section_hdrs;
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- if (type == 0) {
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- shdr_size = sizeof(Elf32_Shdr);
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- memset(&shdr32, 0, shdr_size);
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- shdr32.sh_info = cpu_to_dump32(s, s->phdr_num);
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- shdr = &shdr32;
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+ shdr64->sh_info = cpu_to_dump32(s, s->phdr_num);
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} else {
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- shdr_size = sizeof(Elf64_Shdr);
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- memset(&shdr64, 0, shdr_size);
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- shdr64.sh_info = cpu_to_dump32(s, s->phdr_num);
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- shdr = &shdr64;
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+ Elf32_Shdr *shdr32 = s->elf_section_hdrs;
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+
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+ shdr32->sh_info = cpu_to_dump32(s, s->phdr_num);
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+ }
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+}
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+
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+static void prepare_elf_section_hdrs(DumpState *s)
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+{
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+ size_t len, sizeof_shdr;
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+
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+ /*
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+ * Section ordering:
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+ * - HDR zero
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+ */
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+ sizeof_shdr = dump_is_64bit(s) ? sizeof(Elf64_Shdr) : sizeof(Elf32_Shdr);
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+ len = sizeof_shdr * s->shdr_num;
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+ s->elf_section_hdrs = g_malloc0(len);
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+
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+ /*
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+ * The first section header is ALWAYS a special initial section
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+ * header.
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+ *
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+ * The header should be 0 with one exception being that if
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+ * phdr_num is PN_XNUM then the sh_info field contains the real
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+ * number of segment entries.
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+ *
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+ * As we zero allocate the buffer we will only need to modify
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+ * sh_info for the PN_XNUM case.
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+ */
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+ if (s->phdr_num >= PN_XNUM) {
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+ prepare_elf_section_hdr_zero(s);
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}
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+}
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- ret = fd_write_vmcore(shdr, shdr_size, s);
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+static void write_elf_section_headers(DumpState *s, Error **errp)
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+{
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+ size_t sizeof_shdr = dump_is_64bit(s) ? sizeof(Elf64_Shdr) : sizeof(Elf32_Shdr);
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+ int ret;
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+
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+ prepare_elf_section_hdrs(s);
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+
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+ ret = fd_write_vmcore(s->elf_section_hdrs, s->shdr_num * sizeof_shdr, s);
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if (ret < 0) {
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- error_setg_errno(errp, -ret,
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- "dump: failed to write section header table");
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+ error_setg_errno(errp, -ret, "dump: failed to write section headers");
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}
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+
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+ g_free(s->elf_section_hdrs);
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}
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static void write_data(DumpState *s, void *buf, int length, Error **errp)
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@@ -592,12 +621,10 @@ static void dump_begin(DumpState *s, Error **errp)
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return;
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}
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- /* write section to vmcore */
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- if (s->shdr_num) {
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- write_elf_section(s, 1, errp);
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- if (*errp) {
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- return;
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- }
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+ /* write section headers to vmcore */
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+ write_elf_section_headers(s, errp);
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+ if (*errp) {
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+ return;
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}
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/* write notes to vmcore */
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diff --git a/include/sysemu/dump.h b/include/sysemu/dump.h
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index b62513d87d..9995f65dc8 100644
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--- a/include/sysemu/dump.h
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+++ b/include/sysemu/dump.h
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@@ -177,6 +177,8 @@ typedef struct DumpState {
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int64_t filter_area_begin; /* Start address of partial guest memory area */
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int64_t filter_area_length; /* Length of partial guest memory area */
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+ void *elf_section_hdrs; /* Pointer to section header buffer */
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+
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uint8_t *note_buf; /* buffer for notes */
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size_t note_buf_offset; /* the writing place in note_buf */
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uint32_t nr_cpus; /* number of guest's cpu */
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--
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2.37.3
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