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qemu-kvm/kvm-dump-Add-architecture-section-and-section-string-tab.patch

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From f2f3efff83dddd38a97699cd2701f46f61a732e3 Mon Sep 17 00:00:00 2001
From: Janosch Frank <frankja@linux.ibm.com>
Date: Mon, 17 Oct 2022 11:32:10 +0000
Subject: [PATCH 36/42] dump: Add architecture section and section string table
support
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
RH-Author: Cédric Le Goater <clg@redhat.com>
RH-MergeRequest: 226: s390: Enhanced Interpretation for PCI Functions and Secure Execution guest dump
RH-Bugzilla: 1664378 2043909
RH-Acked-by: Thomas Huth <thuth@redhat.com>
RH-Acked-by: Cornelia Huck <cohuck@redhat.com>
RH-Acked-by: Jon Maloy <jmaloy@redhat.com>
RH-Commit: [36/41] 83b98ff185e93e62703f686b65546d60c783d783
Add hooks which architectures can use to add arbitrary data to custom
sections.
Also add a section name string table in order to identify section
contents
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20221017113210.41674-1-frankja@linux.ibm.com>
(cherry picked from commit 9b72224f44612ddd5b434a1bccf79346946d11da)
Signed-off-by: Cédric Le Goater <clg@redhat.com>
---
dump/dump.c | 186 +++++++++++++++++++++++++++++++------
include/sysemu/dump-arch.h | 3 +
include/sysemu/dump.h | 3 +
3 files changed, 166 insertions(+), 26 deletions(-)
diff --git a/dump/dump.c b/dump/dump.c
index 7a42401790..4aa8fb64d2 100644
--- a/dump/dump.c
+++ b/dump/dump.c
@@ -104,6 +104,7 @@ static int dump_cleanup(DumpState *s)
memory_mapping_list_free(&s->list);
close(s->fd);
g_free(s->guest_note);
+ g_array_unref(s->string_table_buf);
s->guest_note = NULL;
if (s->resume) {
if (s->detached) {
@@ -153,11 +154,10 @@ static void prepare_elf64_header(DumpState *s, Elf64_Ehdr *elf_header)
elf_header->e_phoff = cpu_to_dump64(s, s->phdr_offset);
elf_header->e_phentsize = cpu_to_dump16(s, sizeof(Elf64_Phdr));
elf_header->e_phnum = cpu_to_dump16(s, phnum);
- if (s->shdr_num) {
- elf_header->e_shoff = cpu_to_dump64(s, s->shdr_offset);
- elf_header->e_shentsize = cpu_to_dump16(s, sizeof(Elf64_Shdr));
- elf_header->e_shnum = cpu_to_dump16(s, s->shdr_num);
- }
+ elf_header->e_shoff = cpu_to_dump64(s, s->shdr_offset);
+ elf_header->e_shentsize = cpu_to_dump16(s, sizeof(Elf64_Shdr));
+ elf_header->e_shnum = cpu_to_dump16(s, s->shdr_num);
+ elf_header->e_shstrndx = cpu_to_dump16(s, s->shdr_num - 1);
}
static void prepare_elf32_header(DumpState *s, Elf32_Ehdr *elf_header)
@@ -181,11 +181,10 @@ static void prepare_elf32_header(DumpState *s, Elf32_Ehdr *elf_header)
elf_header->e_phoff = cpu_to_dump32(s, s->phdr_offset);
elf_header->e_phentsize = cpu_to_dump16(s, sizeof(Elf32_Phdr));
elf_header->e_phnum = cpu_to_dump16(s, phnum);
- if (s->shdr_num) {
- elf_header->e_shoff = cpu_to_dump32(s, s->shdr_offset);
- elf_header->e_shentsize = cpu_to_dump16(s, sizeof(Elf32_Shdr));
- elf_header->e_shnum = cpu_to_dump16(s, s->shdr_num);
- }
+ elf_header->e_shoff = cpu_to_dump32(s, s->shdr_offset);
+ elf_header->e_shentsize = cpu_to_dump16(s, sizeof(Elf32_Shdr));
+ elf_header->e_shnum = cpu_to_dump16(s, s->shdr_num);
+ elf_header->e_shstrndx = cpu_to_dump16(s, s->shdr_num - 1);
}
static void write_elf_header(DumpState *s, Error **errp)
@@ -196,6 +195,8 @@ static void write_elf_header(DumpState *s, Error **errp)
void *header_ptr;
int ret;
+ /* The NULL header and the shstrtab are always defined */
+ assert(s->shdr_num >= 2);
if (dump_is_64bit(s)) {
prepare_elf64_header(s, &elf64_header);
header_size = sizeof(elf64_header);
@@ -394,17 +395,49 @@ static void prepare_elf_section_hdr_zero(DumpState *s)
}
}
-static void prepare_elf_section_hdrs(DumpState *s)
+static void prepare_elf_section_hdr_string(DumpState *s, void *buff)
+{
+ uint64_t index = s->string_table_buf->len;
+ const char strtab[] = ".shstrtab";
+ Elf32_Shdr shdr32 = {};
+ Elf64_Shdr shdr64 = {};
+ int shdr_size;
+ void *shdr;
+
+ g_array_append_vals(s->string_table_buf, strtab, sizeof(strtab));
+ if (dump_is_64bit(s)) {
+ shdr_size = sizeof(Elf64_Shdr);
+ shdr64.sh_type = SHT_STRTAB;
+ shdr64.sh_offset = s->section_offset + s->elf_section_data_size;
+ shdr64.sh_name = index;
+ shdr64.sh_size = s->string_table_buf->len;
+ shdr = &shdr64;
+ } else {
+ shdr_size = sizeof(Elf32_Shdr);
+ shdr32.sh_type = SHT_STRTAB;
+ shdr32.sh_offset = s->section_offset + s->elf_section_data_size;
+ shdr32.sh_name = index;
+ shdr32.sh_size = s->string_table_buf->len;
+ shdr = &shdr32;
+ }
+ memcpy(buff, shdr, shdr_size);
+}
+
+static bool prepare_elf_section_hdrs(DumpState *s, Error **errp)
{
size_t len, sizeof_shdr;
+ void *buff_hdr;
/*
* Section ordering:
* - HDR zero
+ * - Arch section hdrs
+ * - String table hdr
*/
sizeof_shdr = dump_is_64bit(s) ? sizeof(Elf64_Shdr) : sizeof(Elf32_Shdr);
len = sizeof_shdr * s->shdr_num;
s->elf_section_hdrs = g_malloc0(len);
+ buff_hdr = s->elf_section_hdrs;
/*
* The first section header is ALWAYS a special initial section
@@ -420,6 +453,26 @@ static void prepare_elf_section_hdrs(DumpState *s)
if (s->phdr_num >= PN_XNUM) {
prepare_elf_section_hdr_zero(s);
}
+ buff_hdr += sizeof_shdr;
+
+ /* Add architecture defined section headers */
+ if (s->dump_info.arch_sections_write_hdr_fn
+ && s->shdr_num > 2) {
+ buff_hdr += s->dump_info.arch_sections_write_hdr_fn(s, buff_hdr);
+
+ if (s->shdr_num >= SHN_LORESERVE) {
+ error_setg_errno(errp, EINVAL,
+ "dump: too many architecture defined sections");
+ return false;
+ }
+ }
+
+ /*
+ * String table is the last section since strings are added via
+ * arch_sections_write_hdr().
+ */
+ prepare_elf_section_hdr_string(s, buff_hdr);
+ return true;
}
static void write_elf_section_headers(DumpState *s, Error **errp)
@@ -427,7 +480,9 @@ static void write_elf_section_headers(DumpState *s, Error **errp)
size_t sizeof_shdr = dump_is_64bit(s) ? sizeof(Elf64_Shdr) : sizeof(Elf32_Shdr);
int ret;
- prepare_elf_section_hdrs(s);
+ if (!prepare_elf_section_hdrs(s, errp)) {
+ return;
+ }
ret = fd_write_vmcore(s->elf_section_hdrs, s->shdr_num * sizeof_shdr, s);
if (ret < 0) {
@@ -437,6 +492,29 @@ static void write_elf_section_headers(DumpState *s, Error **errp)
g_free(s->elf_section_hdrs);
}
+static void write_elf_sections(DumpState *s, Error **errp)
+{
+ int ret;
+
+ if (s->elf_section_data_size) {
+ /* Write architecture section data */
+ ret = fd_write_vmcore(s->elf_section_data,
+ s->elf_section_data_size, s);
+ if (ret < 0) {
+ error_setg_errno(errp, -ret,
+ "dump: failed to write architecture section data");
+ return;
+ }
+ }
+
+ /* Write string table */
+ ret = fd_write_vmcore(s->string_table_buf->data,
+ s->string_table_buf->len, s);
+ if (ret < 0) {
+ error_setg_errno(errp, -ret, "dump: failed to write string table data");
+ }
+}
+
static void write_data(DumpState *s, void *buf, int length, Error **errp)
{
int ret;
@@ -693,6 +771,31 @@ static void dump_iterate(DumpState *s, Error **errp)
}
}
+static void dump_end(DumpState *s, Error **errp)
+{
+ int rc;
+ ERRP_GUARD();
+
+ if (s->elf_section_data_size) {
+ s->elf_section_data = g_malloc0(s->elf_section_data_size);
+ }
+
+ /* Adds the architecture defined section data to s->elf_section_data */
+ if (s->dump_info.arch_sections_write_fn &&
+ s->elf_section_data_size) {
+ rc = s->dump_info.arch_sections_write_fn(s, s->elf_section_data);
+ if (rc) {
+ error_setg_errno(errp, rc,
+ "dump: failed to get arch section data");
+ g_free(s->elf_section_data);
+ return;
+ }
+ }
+
+ /* write sections to vmcore */
+ write_elf_sections(s, errp);
+}
+
static void create_vmcore(DumpState *s, Error **errp)
{
ERRP_GUARD();
@@ -702,7 +805,14 @@ static void create_vmcore(DumpState *s, Error **errp)
return;
}
+ /* Iterate over memory and dump it to file */
dump_iterate(s, errp);
+ if (*errp) {
+ return;
+ }
+
+ /* Write the section data */
+ dump_end(s, errp);
}
static int write_start_flat_header(int fd)
@@ -1720,6 +1830,14 @@ static void dump_init(DumpState *s, int fd, bool has_format,
s->filter_area_begin = begin;
s->filter_area_length = length;
+ /* First index is 0, it's the special null name */
+ s->string_table_buf = g_array_new(FALSE, TRUE, 1);
+ /*
+ * Allocate the null name, due to the clearing option set to true
+ * it will be 0.
+ */
+ g_array_set_size(s->string_table_buf, 1);
+
memory_mapping_list_init(&s->list);
guest_phys_blocks_init(&s->guest_phys_blocks);
@@ -1856,26 +1974,42 @@ static void dump_init(DumpState *s, int fd, bool has_format,
}
/*
- * calculate phdr_num
+ * The first section header is always a special one in which most
+ * fields are 0. The section header string table is also always
+ * set.
+ */
+ s->shdr_num = 2;
+
+ /*
+ * Adds the number of architecture sections to shdr_num and sets
+ * elf_section_data_size so we know the offsets and sizes of all
+ * parts.
+ */
+ if (s->dump_info.arch_sections_add_fn) {
+ s->dump_info.arch_sections_add_fn(s);
+ }
+
+ /*
+ * calculate shdr_num so we know the offsets and sizes of all
+ * parts.
+ * Calculate phdr_num
*
- * the type of ehdr->e_phnum is uint16_t, so we should avoid overflow
+ * The absolute maximum amount of phdrs is UINT32_MAX - 1 as
+ * sh_info is 32 bit. There's special handling once we go over
+ * UINT16_MAX - 1 but that is handled in the ehdr and section
+ * code.
*/
- s->phdr_num = 1; /* PT_NOTE */
- if (s->list.num < UINT16_MAX - 2) {
- s->shdr_num = 0;
+ s->phdr_num = 1; /* Reserve PT_NOTE */
+ if (s->list.num <= UINT32_MAX - 1) {
s->phdr_num += s->list.num;
} else {
- /* sh_info of section 0 holds the real number of phdrs */
- s->shdr_num = 1;
-
- /* the type of shdr->sh_info is uint32_t, so we should avoid overflow */
- if (s->list.num <= UINT32_MAX - 1) {
- s->phdr_num += s->list.num;
- } else {
- s->phdr_num = UINT32_MAX;
- }
+ s->phdr_num = UINT32_MAX;
}
+ /*
+ * Now that the number of section and program headers is known we
+ * can calculate the offsets of the headers and data.
+ */
if (dump_is_64bit(s)) {
s->shdr_offset = sizeof(Elf64_Ehdr);
s->phdr_offset = s->shdr_offset + sizeof(Elf64_Shdr) * s->shdr_num;
diff --git a/include/sysemu/dump-arch.h b/include/sysemu/dump-arch.h
index e25b02e990..59bbc9be38 100644
--- a/include/sysemu/dump-arch.h
+++ b/include/sysemu/dump-arch.h
@@ -21,6 +21,9 @@ typedef struct ArchDumpInfo {
uint32_t page_size; /* The target's page size. If it's variable and
* unknown, then this should be the maximum. */
uint64_t phys_base; /* The target's physmem base. */
+ void (*arch_sections_add_fn)(DumpState *s);
+ uint64_t (*arch_sections_write_hdr_fn)(DumpState *s, uint8_t *buff);
+ int (*arch_sections_write_fn)(DumpState *s, uint8_t *buff);
} ArchDumpInfo;
struct GuestPhysBlockList; /* memory_mapping.h */
diff --git a/include/sysemu/dump.h b/include/sysemu/dump.h
index 9ed811b313..38ccac7190 100644
--- a/include/sysemu/dump.h
+++ b/include/sysemu/dump.h
@@ -180,6 +180,9 @@ typedef struct DumpState {
hwaddr note_offset;
void *elf_section_hdrs; /* Pointer to section header buffer */
+ void *elf_section_data; /* Pointer to section data buffer */
+ uint64_t elf_section_data_size; /* Size of section data */
+ GArray *string_table_buf; /* String table data buffer */
uint8_t *note_buf; /* buffer for notes */
size_t note_buf_offset; /* the writing place in note_buf */
--
2.37.3
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