[PATCH v2 0/9] dump: Cleanup and consolidation

[PATCH v2 0/9] dump: Cleanup and consolidation

[Janosch Frank]

The dump/dump.c file has lots of duplicated code for handling 64 and
32 bit elf files. Additionally there are many instances where code can
be improved by adding a variable to avoid having to specify the same
calculation or check over and over.

This series is the cleanup step onto which my series that adds custom
section support and finally the series that introduces PV dump support
are based on.

Personal comments:
It's taken me quite a while to understand how the code works and I
expect that this patch might improve that but it won't fix every
issue. Going forward it might make sense to split kdump and elf dump
code into separate files and also cleanup the kdump code.

v2:
	* Added the ERRP_GUARD() patch which converts dump.c to the
          new error handling methods
	* Switched patches #2 and #3 around
	* Added a patch that removes the section if/else
	* Moved dump_is_64bit() to dump.c


Janosch Frank (9):
  dump: Use ERRP_GUARD()
  dump: Remove the sh_info variable
  dump: Introduce shdr_num to decrease complexity
  dump: Remove the section if when calculating the memory offset
  dump: Add more offset variables
  dump: Introduce dump_is_64bit() helper function
  dump: Consolidate phdr note writes
  dump: Cleanup dump_begin write functions
  dump: Consolidate elf note function

 dump/dump.c           | 361 ++++++++++++++++++------------------------
 include/sysemu/dump.h |   9 +-
 2 files changed, 164 insertions(+), 206 deletions(-)

-- 
2.32.0

[PATCH v2 1/9] dump: Use ERRP_GUARD()

[Janosch Frank]

Let's move to the new way of handling errors before changing the dump
code. This patch has mostly been generated by the coccinelle script
scripts/coccinelle/errp-guard.cocci.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
---
 dump/dump.c | 144 ++++++++++++++++++++++------------------------------
 1 file changed, 61 insertions(+), 83 deletions(-)

diff --git a/dump/dump.c b/dump/dump.c
index a84d8b1598..ef1700174b 100644
--- a/dump/dump.c
+++ b/dump/dump.c
@@ -390,23 +390,21 @@ static void write_data(DumpState *s, void *buf, int length, Error **errp)
 static void write_memory(DumpState *s, GuestPhysBlock *block, ram_addr_t start,
                          int64_t size, Error **errp)
 {
+    ERRP_GUARD();
     int64_t i;
-    Error *local_err = NULL;
 
     for (i = 0; i < size / s->dump_info.page_size; i++) {
         write_data(s, block->host_addr + start + i * s->dump_info.page_size,
-                   s->dump_info.page_size, &local_err);
-        if (local_err) {
-            error_propagate(errp, local_err);
+                   s->dump_info.page_size, errp);
+        if (*errp) {
             return;
         }
     }
 
     if ((size % s->dump_info.page_size) != 0) {
         write_data(s, block->host_addr + start + i * s->dump_info.page_size,
-                   size % s->dump_info.page_size, &local_err);
-        if (local_err) {
-            error_propagate(errp, local_err);
+                   size % s->dump_info.page_size, errp);
+        if (*errp) {
             return;
         }
     }
@@ -476,11 +474,11 @@ static void get_offset_range(hwaddr phys_addr,
 
 static void write_elf_loads(DumpState *s, Error **errp)
 {
+    ERRP_GUARD();
     hwaddr offset, filesz;
     MemoryMapping *memory_mapping;
     uint32_t phdr_index = 1;
     uint32_t max_index;
-    Error *local_err = NULL;
 
     if (s->have_section) {
         max_index = s->sh_info;
@@ -494,14 +492,13 @@ static void write_elf_loads(DumpState *s, Error **errp)
                          s, &offset, &filesz);
         if (s->dump_info.d_class == ELFCLASS64) {
             write_elf64_load(s, memory_mapping, phdr_index++, offset,
-                             filesz, &local_err);
+                             filesz, errp);
         } else {
             write_elf32_load(s, memory_mapping, phdr_index++, offset,
-                             filesz, &local_err);
+                             filesz, errp);
         }
 
-        if (local_err) {
-            error_propagate(errp, local_err);
+        if (*errp) {
             return;
         }
 
@@ -514,7 +511,7 @@ static void write_elf_loads(DumpState *s, Error **errp)
 /* write elf header, PT_NOTE and elf note to vmcore. */
 static void dump_begin(DumpState *s, Error **errp)
 {
-    Error *local_err = NULL;
+    ERRP_GUARD();
 
     /*
      * the vmcore's format is:
@@ -542,73 +539,64 @@ static void dump_begin(DumpState *s, Error **errp)
 
     /* write elf header to vmcore */
     if (s->dump_info.d_class == ELFCLASS64) {
-        write_elf64_header(s, &local_err);
+        write_elf64_header(s, errp);
     } else {
-        write_elf32_header(s, &local_err);
+        write_elf32_header(s, errp);
     }
-    if (local_err) {
-        error_propagate(errp, local_err);
+    if (*errp) {
         return;
     }
 
     if (s->dump_info.d_class == ELFCLASS64) {
         /* write PT_NOTE to vmcore */
-        write_elf64_note(s, &local_err);
-        if (local_err) {
-            error_propagate(errp, local_err);
+        write_elf64_note(s, errp);
+        if (*errp) {
             return;
         }
 
         /* write all PT_LOAD to vmcore */
-        write_elf_loads(s, &local_err);
-        if (local_err) {
-            error_propagate(errp, local_err);
+        write_elf_loads(s, errp);
+        if (*errp) {
             return;
         }
 
         /* write section to vmcore */
         if (s->have_section) {
-            write_elf_section(s, 1, &local_err);
-            if (local_err) {
-                error_propagate(errp, local_err);
+            write_elf_section(s, 1, errp);
+            if (*errp) {
                 return;
             }
         }
 
         /* write notes to vmcore */
-        write_elf64_notes(fd_write_vmcore, s, &local_err);
-        if (local_err) {
-            error_propagate(errp, local_err);
+        write_elf64_notes(fd_write_vmcore, s, errp);
+        if (*errp) {
             return;
         }
     } else {
         /* write PT_NOTE to vmcore */
-        write_elf32_note(s, &local_err);
-        if (local_err) {
-            error_propagate(errp, local_err);
+        write_elf32_note(s, errp);
+        if (*errp) {
             return;
         }
 
         /* write all PT_LOAD to vmcore */
-        write_elf_loads(s, &local_err);
-        if (local_err) {
-            error_propagate(errp, local_err);
+        write_elf_loads(s, errp);
+        if (*errp) {
             return;
         }
 
         /* write section to vmcore */
         if (s->have_section) {
-            write_elf_section(s, 0, &local_err);
-            if (local_err) {
-                error_propagate(errp, local_err);
+            write_elf_section(s, 0, errp);
+            if (*errp) {
                 return;
             }
         }
 
         /* write notes to vmcore */
-        write_elf32_notes(fd_write_vmcore, s, &local_err);
-        if (local_err) {
-            error_propagate(errp, local_err);
+        write_elf32_notes(fd_write_vmcore, s, errp);
+        if (*errp) {
             return;
         }
     }
@@ -644,9 +632,9 @@ static int get_next_block(DumpState *s, GuestPhysBlock *block)
 /* write all memory to vmcore */
 static void dump_iterate(DumpState *s, Error **errp)
 {
+    ERRP_GUARD();
     GuestPhysBlock *block;
     int64_t size;
-    Error *local_err = NULL;
 
     do {
         block = s->next_block;
@@ -658,9 +646,8 @@ static void dump_iterate(DumpState *s, Error **errp)
                 size -= block->target_end - (s->begin + s->length);
             }
         }
-        write_memory(s, block, s->start, size, &local_err);
-        if (local_err) {
-            error_propagate(errp, local_err);
+        write_memory(s, block, s->start, size, errp);
+        if (*errp) {
             return;
         }
 
@@ -669,11 +656,10 @@ static void dump_iterate(DumpState *s, Error **errp)
 
 static void create_vmcore(DumpState *s, Error **errp)
 {
-    Error *local_err = NULL;
+    ERRP_GUARD();
 
-    dump_begin(s, &local_err);
-    if (local_err) {
-        error_propagate(errp, local_err);
+    dump_begin(s, errp);
+    if (*errp) {
         return;
     }
 
@@ -810,6 +796,7 @@ static bool note_name_equal(DumpState *s,
 /* write common header, sub header and elf note to vmcore */
 static void create_header32(DumpState *s, Error **errp)
 {
+    ERRP_GUARD();
     DiskDumpHeader32 *dh = NULL;
     KdumpSubHeader32 *kh = NULL;
     size_t size;
@@ -818,7 +805,6 @@ static void create_header32(DumpState *s, Error **errp)
     uint32_t bitmap_blocks;
     uint32_t status = 0;
     uint64_t offset_note;
-    Error *local_err = NULL;
 
     /* write common header, the version of kdump-compressed format is 6th */
     size = sizeof(DiskDumpHeader32);
@@ -894,9 +880,8 @@ static void create_header32(DumpState *s, Error **errp)
     s->note_buf_offset = 0;
 
     /* use s->note_buf to store notes temporarily */
-    write_elf32_notes(buf_write_note, s, &local_err);
-    if (local_err) {
-        error_propagate(errp, local_err);
+    write_elf32_notes(buf_write_note, s, errp);
+    if (*errp) {
         goto out;
     }
     if (write_buffer(s->fd, offset_note, s->note_buf,
@@ -922,6 +907,7 @@ out:
 /* write common header, sub header and elf note to vmcore */
 static void create_header64(DumpState *s, Error **errp)
 {
+    ERRP_GUARD();
     DiskDumpHeader64 *dh = NULL;
     KdumpSubHeader64 *kh = NULL;
     size_t size;
@@ -930,7 +916,6 @@ static void create_header64(DumpState *s, Error **errp)
     uint32_t bitmap_blocks;
     uint32_t status = 0;
     uint64_t offset_note;
-    Error *local_err = NULL;
 
     /* write common header, the version of kdump-compressed format is 6th */
     size = sizeof(DiskDumpHeader64);
@@ -1006,9 +991,8 @@ static void create_header64(DumpState *s, Error **errp)
     s->note_buf_offset = 0;
 
     /* use s->note_buf to store notes temporarily */
-    write_elf64_notes(buf_write_note, s, &local_err);
-    if (local_err) {
-        error_propagate(errp, local_err);
+    write_elf64_notes(buf_write_note, s, errp);
+    if (*errp) {
         goto out;
     }
 
@@ -1464,8 +1448,8 @@ out:
 
 static void create_kdump_vmcore(DumpState *s, Error **errp)
 {
+    ERRP_GUARD();
     int ret;
-    Error *local_err = NULL;
 
     /*
      * the kdump-compressed format is:
@@ -1495,21 +1479,18 @@ static void create_kdump_vmcore(DumpState *s, Error **errp)
         return;
     }
 
-    write_dump_header(s, &local_err);
-    if (local_err) {
-        error_propagate(errp, local_err);
+    write_dump_header(s, errp);
+    if (*errp) {
         return;
     }
 
-    write_dump_bitmap(s, &local_err);
-    if (local_err) {
-        error_propagate(errp, local_err);
+    write_dump_bitmap(s, errp);
+    if (*errp) {
         return;
     }
 
-    write_dump_pages(s, &local_err);
-    if (local_err) {
-        error_propagate(errp, local_err);
+    write_dump_pages(s, errp);
+    if (*errp) {
         return;
     }
 
@@ -1639,10 +1620,10 @@ static void dump_init(DumpState *s, int fd, bool has_format,
                       DumpGuestMemoryFormat format, bool paging, bool has_filter,
                       int64_t begin, int64_t length, Error **errp)
 {
+    ERRP_GUARD();
     VMCoreInfoState *vmci = vmcoreinfo_find();
     CPUState *cpu;
     int nr_cpus;
-    Error *err = NULL;
     int ret;
 
     s->has_format = has_format;
@@ -1761,9 +1742,8 @@ static void dump_init(DumpState *s, int fd, bool has_format,
 
     /* get memory mapping */
     if (paging) {
-        qemu_get_guest_memory_mapping(&s->list, &s->guest_phys_blocks, &err);
-        if (err != NULL) {
-            error_propagate(errp, err);
+        qemu_get_guest_memory_mapping(&s->list, &s->guest_phys_blocks, errp);
+        if (*errp) {
             goto cleanup;
         }
     } else {
@@ -1862,33 +1842,32 @@ cleanup:
 /* this operation might be time consuming. */
 static void dump_process(DumpState *s, Error **errp)
 {
-    Error *local_err = NULL;
+    ERRP_GUARD();
     DumpQueryResult *result = NULL;
 
     if (s->has_format && s->format == DUMP_GUEST_MEMORY_FORMAT_WIN_DMP) {
 #ifdef TARGET_X86_64
-        create_win_dump(s, &local_err);
+        create_win_dump(s, errp);
 #endif
     } else if (s->has_format && s->format != DUMP_GUEST_MEMORY_FORMAT_ELF) {
-        create_kdump_vmcore(s, &local_err);
+        create_kdump_vmcore(s, errp);
     } else {
-        create_vmcore(s, &local_err);
+        create_vmcore(s, errp);
     }
 
     /* make sure status is written after written_size updates */
     smp_wmb();
     qatomic_set(&s->status,
-               (local_err ? DUMP_STATUS_FAILED : DUMP_STATUS_COMPLETED));
+               (*errp ? DUMP_STATUS_FAILED : DUMP_STATUS_COMPLETED));
 
     /* send DUMP_COMPLETED message (unconditionally) */
     result = qmp_query_dump(NULL);
     /* should never fail */
     assert(result);
-    qapi_event_send_dump_completed(result, !!local_err, (local_err ?
-                                   error_get_pretty(local_err) : NULL));
+    qapi_event_send_dump_completed(result, !!*errp, (*errp ?
+                                                     error_get_pretty(*errp) : NULL));
     qapi_free_DumpQueryResult(result);
 
-    error_propagate(errp, local_err);
     dump_cleanup(s);
 }
 
@@ -1917,10 +1896,10 @@ void qmp_dump_guest_memory(bool paging, const char *file,
                            int64_t length, bool has_format,
                            DumpGuestMemoryFormat format, Error **errp)
 {
+    ERRP_GUARD();
     const char *p;
     int fd = -1;
     DumpState *s;
-    Error *local_err = NULL;
     bool detach_p = false;
 
     if (runstate_check(RUN_STATE_INMIGRATE)) {
@@ -2020,9 +1999,8 @@ void qmp_dump_guest_memory(bool paging, const char *file,
     dump_state_prepare(s);
 
     dump_init(s, fd, has_format, format, paging, has_begin,
-              begin, length, &local_err);
-    if (local_err) {
-        error_propagate(errp, local_err);
+              begin, length, errp);
+    if (*errp) {
         qatomic_set(&s->status, DUMP_STATUS_FAILED);
         return;
     }
-- 
2.32.0

Re: [PATCH v2 1/9] dump: Use ERRP_GUARD()

[Richard Henderson]

On 3/10/22 03:08, Janosch Frank wrote:
> Let's move to the new way of handling errors before changing the dump
> code. This patch has mostly been generated by the coccinelle script
> scripts/coccinelle/errp-guard.cocci.
> 
> Signed-off-by: Janosch Frank<frankja@linux.ibm.com>
> ---
>   dump/dump.c | 144 ++++++++++++++++++++++------------------------------
>   1 file changed, 61 insertions(+), 83 deletions(-)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~

[PATCH v2 2/9] dump: Remove the sh_info variable

[Janosch Frank]

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 <frankja@linux.ibm.com>
---
 dump/dump.c           | 34 ++++++++++++++--------------------
 include/sysemu/dump.h |  3 +--
 2 files changed, 15 insertions(+), 22 deletions(-)

diff --git a/dump/dump.c b/dump/dump.c
index ef1700174b..7015c92177 100644
--- a/dump/dump.c
+++ b/dump/dump.c
@@ -124,6 +124,7 @@ static int fd_write_vmcore(const void *buf, size_t size, void *opaque)
 
 static void write_elf64_header(DumpState *s, Error **errp)
 {
+    uint16_t phnum = s->phdr_num >= PN_XNUM ? PN_XNUM : s->phdr_num;
     Elf64_Ehdr elf_header;
     int ret;
 
@@ -138,9 +139,9 @@ 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 +156,7 @@ static void write_elf64_header(DumpState *s, Error **errp)
 
 static void write_elf32_header(DumpState *s, Error **errp)
 {
+    uint16_t phnum = s->phdr_num >= PN_XNUM ? PN_XNUM : s->phdr_num;
     Elf32_Ehdr elf_header;
     int ret;
 
@@ -169,9 +171,9 @@ 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 +360,12 @@ 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 +480,6 @@ 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 +497,7 @@ static void write_elf_loads(DumpState *s, Error **errp)
             return;
         }
 
-        if (phdr_index >= max_index) {
+        if (phdr_index >= s->phdr_num) {
             break;
         }
     }
@@ -1801,22 +1796,21 @@ 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 +1819,7 @@ 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;
-- 
2.32.0

Re: [PATCH v2 2/9] dump: Remove the sh_info variable

[Richard Henderson]

On 3/10/22 03:08, Janosch Frank wrote:
> 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<frankja@linux.ibm.com>
> ---
>   dump/dump.c           | 34 ++++++++++++++--------------------
>   include/sysemu/dump.h |  3 +--
>   2 files changed, 15 insertions(+), 22 deletions(-)

Nice.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~

[PATCH v2 3/9] dump: Introduce shdr_num to decrease complexity

[Janosch Frank]

Let's move from a boolean to a int variable which will later enable us
to store the number of sections that are in the dump file.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
---
 dump/dump.c           | 24 ++++++++++++------------
 include/sysemu/dump.h |  2 +-
 2 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/dump/dump.c b/dump/dump.c
index 7015c92177..c5ca6027ae 100644
--- a/dump/dump.c
+++ b/dump/dump.c
@@ -140,12 +140,12 @@ static void write_elf64_header(DumpState *s, Error **errp)
     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, phnum);
-    if (s->have_section) {
+    if (s->shdr_num) {
         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));
-        elf_header.e_shnum = cpu_to_dump16(s, 1);
+        elf_header.e_shnum = cpu_to_dump16(s, s->shdr_num);
     }
 
     ret = fd_write_vmcore(&elf_header, sizeof(elf_header), s);
@@ -172,12 +172,12 @@ static void write_elf32_header(DumpState *s, Error **errp)
     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, phnum);
-    if (s->have_section) {
+    if (s->shdr_num) {
         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));
-        elf_header.e_shnum = cpu_to_dump16(s, 1);
+        elf_header.e_shnum = cpu_to_dump16(s, s->shdr_num);
     }
 
     ret = fd_write_vmcore(&elf_header, sizeof(elf_header), s);
@@ -556,7 +556,7 @@ static void dump_begin(DumpState *s, Error **errp)
         }
 
         /* write section to vmcore */
-        if (s->have_section) {
+        if (s->shdr_num) {
             write_elf_section(s, 1, errp);
             if (*errp) {
                 return;
@@ -582,7 +582,7 @@ static void dump_begin(DumpState *s, Error **errp)
         }
 
         /* write section to vmcore */
-        if (s->have_section) {
+        if (s->shdr_num) {
             write_elf_section(s, 0, errp);
             if (*errp) {
                 return;
@@ -1793,11 +1793,11 @@ static void dump_init(DumpState *s, int fd, bool has_format,
      */
     s->phdr_num = 1; /* PT_NOTE */
     if (s->list.num < UINT16_MAX - 2) {
+        s->shdr_num = 0;
         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->shdr_num = 1;
 
         /* the type of shdr->sh_info is uint32_t, so we should avoid overflow */
         if (s->list.num <= UINT32_MAX - 1) {
@@ -1808,19 +1808,19 @@ static void dump_init(DumpState *s, int fd, bool has_format,
     }
 
     if (s->dump_info.d_class == ELFCLASS64) {
-        if (s->have_section) {
+        if (s->shdr_num) {
             s->memory_offset = sizeof(Elf64_Ehdr) +
                                sizeof(Elf64_Phdr) * s->phdr_num +
-                               sizeof(Elf64_Shdr) + s->note_size;
+                               sizeof(Elf64_Shdr) * s->shdr_num + s->note_size;
         } else {
             s->memory_offset = sizeof(Elf64_Ehdr) +
                                sizeof(Elf64_Phdr) * s->phdr_num + s->note_size;
         }
     } else {
-        if (s->have_section) {
+        if (s->shdr_num) {
             s->memory_offset = sizeof(Elf32_Ehdr) +
                                sizeof(Elf32_Phdr) * s->phdr_num +
-                               sizeof(Elf32_Shdr) + s->note_size;
+                               sizeof(Elf32_Shdr) * s->shdr_num + s->note_size;
         } else {
             s->memory_offset = sizeof(Elf32_Ehdr) +
                                sizeof(Elf32_Phdr) * s->phdr_num + s->note_size;
diff --git a/include/sysemu/dump.h b/include/sysemu/dump.h
index b463fc9c02..19458bffbd 100644
--- a/include/sysemu/dump.h
+++ b/include/sysemu/dump.h
@@ -155,7 +155,7 @@ typedef struct DumpState {
     ArchDumpInfo dump_info;
     MemoryMappingList list;
     uint32_t phdr_num;
-    bool have_section;
+    uint32_t shdr_num;
     bool resume;
     bool detached;
     ssize_t note_size;
-- 
2.32.0

Re: [PATCH v2 3/9] dump: Introduce shdr_num to decrease complexity

[Richard Henderson]

On 3/10/22 03:08, Janosch Frank wrote:
> Let's move from a boolean to a int variable which will later enable us
> to store the number of sections that are in the dump file.
> 
> Signed-off-by: Janosch Frank<frankja@linux.ibm.com>
> ---
>   dump/dump.c           | 24 ++++++++++++------------
>   include/sysemu/dump.h |  2 +-
>   2 files changed, 13 insertions(+), 13 deletions(-)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~

[PATCH v2 4/9] dump: Remove the section if when calculating the memory offset

[Janosch Frank]

When s->shdr_num is 0 we'll add 0 bytes of section headers which is
equivalent to not adding section headers but with the multiplication
we can remove a if/else.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
---
 dump/dump.c | 24 ++++++++----------------
 1 file changed, 8 insertions(+), 16 deletions(-)

diff --git a/dump/dump.c b/dump/dump.c
index c5ca6027ae..316c636f24 100644
--- a/dump/dump.c
+++ b/dump/dump.c
@@ -1808,23 +1808,15 @@ static void dump_init(DumpState *s, int fd, bool has_format,
     }
 
     if (s->dump_info.d_class == ELFCLASS64) {
-        if (s->shdr_num) {
-            s->memory_offset = sizeof(Elf64_Ehdr) +
-                               sizeof(Elf64_Phdr) * s->phdr_num +
-                               sizeof(Elf64_Shdr) * s->shdr_num + s->note_size;
-        } else {
-            s->memory_offset = sizeof(Elf64_Ehdr) +
-                               sizeof(Elf64_Phdr) * s->phdr_num + s->note_size;
-        }
+        s->memory_offset = sizeof(Elf64_Ehdr) +
+                           sizeof(Elf64_Phdr) * s->phdr_num +
+                           sizeof(Elf64_Shdr) * s->shdr_num +
+                           s->note_size;
     } else {
-        if (s->shdr_num) {
-            s->memory_offset = sizeof(Elf32_Ehdr) +
-                               sizeof(Elf32_Phdr) * s->phdr_num +
-                               sizeof(Elf32_Shdr) * s->shdr_num + s->note_size;
-        } else {
-            s->memory_offset = sizeof(Elf32_Ehdr) +
-                               sizeof(Elf32_Phdr) * s->phdr_num + s->note_size;
-        }
+        s->memory_offset = sizeof(Elf32_Ehdr) +
+                           sizeof(Elf32_Phdr) * s->phdr_num +
+                           sizeof(Elf32_Shdr) * s->shdr_num +
+                           s->note_size;
     }
 
     return;
-- 
2.32.0

Re: [PATCH v2 4/9] dump: Remove the section if when calculating the memory offset

[Richard Henderson]

On 3/10/22 03:08, Janosch Frank wrote:
> When s->shdr_num is 0 we'll add 0 bytes of section headers which is
> equivalent to not adding section headers but with the multiplication
> we can remove a if/else.
> 
> Signed-off-by: Janosch Frank<frankja@linux.ibm.com>
> ---
>   dump/dump.c | 24 ++++++++----------------
>   1 file changed, 8 insertions(+), 16 deletions(-)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~

[PATCH v2 5/9] dump: Add more offset variables

[Janosch Frank]

Offset calculations are easy enough to get wrong. Let's add a few
variables to make moving around elf headers and data sections easier.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
---
 dump/dump.c           | 35 +++++++++++++++--------------------
 include/sysemu/dump.h |  4 ++++
 2 files changed, 19 insertions(+), 20 deletions(-)

diff --git a/dump/dump.c b/dump/dump.c
index 316c636f24..12b3a1a83e 100644
--- a/dump/dump.c
+++ b/dump/dump.c
@@ -137,13 +137,11 @@ static void write_elf64_header(DumpState *s, Error **errp)
     elf_header.e_machine = cpu_to_dump16(s, s->dump_info.d_machine);
     elf_header.e_version = cpu_to_dump32(s, EV_CURRENT);
     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_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) {
-        uint64_t shoff = sizeof(Elf64_Ehdr) + sizeof(Elf64_Phdr) * s->phdr_num;
-
-        elf_header.e_shoff = cpu_to_dump64(s, shoff);
+        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);
     }
@@ -169,13 +167,11 @@ static void write_elf32_header(DumpState *s, Error **errp)
     elf_header.e_machine = cpu_to_dump16(s, s->dump_info.d_machine);
     elf_header.e_version = cpu_to_dump32(s, EV_CURRENT);
     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_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) {
-        uint32_t shoff = sizeof(Elf32_Ehdr) + sizeof(Elf32_Phdr) * s->phdr_num;
-
-        elf_header.e_shoff = cpu_to_dump32(s, shoff);
+        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);
     }
@@ -238,12 +234,11 @@ static void write_elf32_load(DumpState *s, MemoryMapping *memory_mapping,
 static void write_elf64_note(DumpState *s, Error **errp)
 {
     Elf64_Phdr phdr;
-    hwaddr begin = s->memory_offset - s->note_size;
     int ret;
 
     memset(&phdr, 0, sizeof(Elf64_Phdr));
     phdr.p_type = cpu_to_dump32(s, PT_NOTE);
-    phdr.p_offset = cpu_to_dump64(s, begin);
+    phdr.p_offset = cpu_to_dump64(s, s->note_offset);
     phdr.p_paddr = 0;
     phdr.p_filesz = cpu_to_dump64(s, s->note_size);
     phdr.p_memsz = cpu_to_dump64(s, s->note_size);
@@ -303,13 +298,12 @@ static void write_elf64_notes(WriteCoreDumpFunction f, DumpState *s,
 
 static void write_elf32_note(DumpState *s, Error **errp)
 {
-    hwaddr begin = s->memory_offset - s->note_size;
     Elf32_Phdr phdr;
     int ret;
 
     memset(&phdr, 0, sizeof(Elf32_Phdr));
     phdr.p_type = cpu_to_dump32(s, PT_NOTE);
-    phdr.p_offset = cpu_to_dump32(s, begin);
+    phdr.p_offset = cpu_to_dump32(s, s->note_offset);
     phdr.p_paddr = 0;
     phdr.p_filesz = cpu_to_dump32(s, s->note_size);
     phdr.p_memsz = cpu_to_dump32(s, s->note_size);
@@ -1808,15 +1802,16 @@ static void dump_init(DumpState *s, int fd, bool has_format,
     }
 
     if (s->dump_info.d_class == ELFCLASS64) {
-        s->memory_offset = sizeof(Elf64_Ehdr) +
-                           sizeof(Elf64_Phdr) * s->phdr_num +
-                           sizeof(Elf64_Shdr) * s->shdr_num +
-                           s->note_size;
+        s->phdr_offset = sizeof(Elf64_Ehdr);
+        s->shdr_offset = s->phdr_offset + sizeof(Elf64_Phdr) * s->phdr_num;
+        s->note_offset = s->shdr_offset + sizeof(Elf64_Shdr) * s->shdr_num;
+        s->memory_offset = s->note_offset + s->note_size;
     } else {
-        s->memory_offset = sizeof(Elf32_Ehdr) +
-                           sizeof(Elf32_Phdr) * s->phdr_num +
-                           sizeof(Elf32_Shdr) * s->shdr_num +
-                           s->note_size;
+
+        s->phdr_offset = sizeof(Elf32_Ehdr);
+        s->shdr_offset = s->phdr_offset + sizeof(Elf32_Phdr) * s->phdr_num;
+        s->note_offset = s->shdr_offset + sizeof(Elf32_Shdr) * s->shdr_num;
+        s->memory_offset = s->note_offset + s->note_size;
     }
 
     return;
diff --git a/include/sysemu/dump.h b/include/sysemu/dump.h
index 19458bffbd..ffc2ea1072 100644
--- a/include/sysemu/dump.h
+++ b/include/sysemu/dump.h
@@ -159,6 +159,10 @@ typedef struct DumpState {
     bool resume;
     bool detached;
     ssize_t note_size;
+    hwaddr shdr_offset;
+    hwaddr phdr_offset;
+    hwaddr section_offset;
+    hwaddr note_offset;
     hwaddr memory_offset;
     int fd;
 
-- 
2.32.0

Re: [PATCH v2 5/9] dump: Add more offset variables

[Richard Henderson]

On 3/10/22 03:08, Janosch Frank wrote:
> Offset calculations are easy enough to get wrong. Let's add a few
> variables to make moving around elf headers and data sections easier.
> 
> Signed-off-by: Janosch Frank<frankja@linux.ibm.com>
> Reviewed-by: Marc-André Lureau<marcandre.lureau@redhat.com>
> ---
>   dump/dump.c           | 35 +++++++++++++++--------------------
>   include/sysemu/dump.h |  4 ++++
>   2 files changed, 19 insertions(+), 20 deletions(-)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~

[PATCH v2 6/9] dump: Introduce dump_is_64bit() helper function

[Janosch Frank]

Checking d_class in dump_info leads to lengthy conditionals so let's
shorten things a bit by introducing a helper function.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
---
 dump/dump.c | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/dump/dump.c b/dump/dump.c
index 12b3a1a83e..8fcd23571f 100644
--- a/dump/dump.c
+++ b/dump/dump.c
@@ -55,6 +55,11 @@ static Error *dump_migration_blocker;
       DIV_ROUND_UP((name_size), 4) +                    \
       DIV_ROUND_UP((desc_size), 4)) * 4)
 
+static inline bool dump_is_64bit(DumpState *s)
+{
+    return s->dump_info.d_class == ELFCLASS64;
+}
+
 uint16_t cpu_to_dump16(DumpState *s, uint16_t val)
 {
     if (s->dump_info.d_endian == ELFDATA2LSB) {
@@ -479,7 +484,7 @@ static void write_elf_loads(DumpState *s, Error **errp)
         get_offset_range(memory_mapping->phys_addr,
                          memory_mapping->length,
                          s, &offset, &filesz);
-        if (s->dump_info.d_class == ELFCLASS64) {
+        if (dump_is_64bit(s)) {
             write_elf64_load(s, memory_mapping, phdr_index++, offset,
                              filesz, errp);
         } else {
@@ -527,7 +532,7 @@ static void dump_begin(DumpState *s, Error **errp)
      */
 
     /* write elf header to vmcore */
-    if (s->dump_info.d_class == ELFCLASS64) {
+    if (dump_is_64bit(s)) {
         write_elf64_header(s, errp);
     } else {
         write_elf32_header(s, errp);
@@ -536,7 +541,7 @@ static void dump_begin(DumpState *s, Error **errp)
         return;
     }
 
-    if (s->dump_info.d_class == ELFCLASS64) {
+    if (dump_is_64bit(s)) {
         /* write PT_NOTE to vmcore */
         write_elf64_note(s, errp);
         if (*errp) {
@@ -747,7 +752,7 @@ static void get_note_sizes(DumpState *s, const void *note,
     uint64_t name_sz;
     uint64_t desc_sz;
 
-    if (s->dump_info.d_class == ELFCLASS64) {
+    if (dump_is_64bit(s)) {
         const Elf64_Nhdr *hdr = note;
         note_head_sz = sizeof(Elf64_Nhdr);
         name_sz = tswap64(hdr->n_namesz);
@@ -1007,7 +1012,7 @@ out:
 
 static void write_dump_header(DumpState *s, Error **errp)
 {
-    if (s->dump_info.d_class == ELFCLASS32) {
+    if (!dump_is_64bit(s)) {
         create_header32(s, errp);
     } else {
         create_header64(s, errp);
@@ -1697,7 +1702,7 @@ static void dump_init(DumpState *s, int fd, bool has_format,
         uint32_t size;
         uint16_t format;
 
-        note_head_size = s->dump_info.d_class == ELFCLASS32 ?
+        note_head_size = !dump_is_64bit(s) ?
             sizeof(Elf32_Nhdr) : sizeof(Elf64_Nhdr);
 
         format = le16_to_cpu(vmci->vmcoreinfo.guest_format);
@@ -1801,7 +1806,7 @@ static void dump_init(DumpState *s, int fd, bool has_format,
         }
     }
 
-    if (s->dump_info.d_class == ELFCLASS64) {
+    if (dump_is_64bit(s)) {
         s->phdr_offset = sizeof(Elf64_Ehdr);
         s->shdr_offset = s->phdr_offset + sizeof(Elf64_Phdr) * s->phdr_num;
         s->note_offset = s->shdr_offset + sizeof(Elf64_Shdr) * s->shdr_num;
-- 
2.32.0

Re: [PATCH v2 6/9] dump: Introduce dump_is_64bit() helper function

[Richard Henderson]

On 3/10/22 03:08, Janosch Frank wrote:
> Checking d_class in dump_info leads to lengthy conditionals so let's
> shorten things a bit by introducing a helper function.
> 
> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
> ---
>   dump/dump.c | 19 ++++++++++++-------
>   1 file changed, 12 insertions(+), 7 deletions(-)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

> @@ -1007,7 +1012,7 @@ out:
>   
>   static void write_dump_header(DumpState *s, Error **errp)
>   {
> -    if (s->dump_info.d_class == ELFCLASS32) {
> +    if (!dump_is_64bit(s)) {
>           create_header32(s, errp);
>       } else {
>           create_header64(s, errp);
> @@ -1697,7 +1702,7 @@ static void dump_init(DumpState *s, int fd, bool has_format,
>           uint32_t size;
>           uint16_t format;
>   
> -        note_head_size = s->dump_info.d_class == ELFCLASS32 ?
> +        note_head_size = !dump_is_64bit(s) ?
>               sizeof(Elf32_Nhdr) : sizeof(Elf64_Nhdr);

It would be nice to standardize on positive tests, which in this case would reverse these 
two conditionals.


r~

[PATCH v2 7/9] dump: Consolidate phdr note writes

[Janosch Frank]

There's no need to have two write functions. Let's rather have two
functions that set the data for elf 32/64 and then write it in a
common function.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
---
 dump/dump.c | 94 +++++++++++++++++++++++++++--------------------------
 1 file changed, 48 insertions(+), 46 deletions(-)

diff --git a/dump/dump.c b/dump/dump.c
index 8fcd23571f..1294673444 100644
--- a/dump/dump.c
+++ b/dump/dump.c
@@ -236,24 +236,15 @@ static void write_elf32_load(DumpState *s, MemoryMapping *memory_mapping,
     }
 }
 
-static void write_elf64_note(DumpState *s, Error **errp)
+static void write_elf64_phdr_note(DumpState *s, Elf64_Phdr *phdr)
 {
-    Elf64_Phdr phdr;
-    int ret;
-
-    memset(&phdr, 0, sizeof(Elf64_Phdr));
-    phdr.p_type = cpu_to_dump32(s, PT_NOTE);
-    phdr.p_offset = cpu_to_dump64(s, s->note_offset);
-    phdr.p_paddr = 0;
-    phdr.p_filesz = cpu_to_dump64(s, s->note_size);
-    phdr.p_memsz = cpu_to_dump64(s, s->note_size);
-    phdr.p_vaddr = 0;
-
-    ret = fd_write_vmcore(&phdr, sizeof(Elf64_Phdr), s);
-    if (ret < 0) {
-        error_setg_errno(errp, -ret,
-                         "dump: failed to write program header table");
-    }
+    memset(phdr, 0, sizeof(*phdr));
+    phdr->p_type = cpu_to_dump32(s, PT_NOTE);
+    phdr->p_offset = cpu_to_dump64(s, s->note_offset);
+    phdr->p_paddr = 0;
+    phdr->p_filesz = cpu_to_dump64(s, s->note_size);
+    phdr->p_memsz = cpu_to_dump64(s, s->note_size);
+    phdr->p_vaddr = 0;
 }
 
 static inline int cpu_index(CPUState *cpu)
@@ -301,24 +292,15 @@ static void write_elf64_notes(WriteCoreDumpFunction f, DumpState *s,
     write_guest_note(f, s, errp);
 }
 
-static void write_elf32_note(DumpState *s, Error **errp)
+static void write_elf32_phdr_note(DumpState *s, Elf32_Phdr *phdr)
 {
-    Elf32_Phdr phdr;
-    int ret;
-
-    memset(&phdr, 0, sizeof(Elf32_Phdr));
-    phdr.p_type = cpu_to_dump32(s, PT_NOTE);
-    phdr.p_offset = cpu_to_dump32(s, s->note_offset);
-    phdr.p_paddr = 0;
-    phdr.p_filesz = cpu_to_dump32(s, s->note_size);
-    phdr.p_memsz = cpu_to_dump32(s, s->note_size);
-    phdr.p_vaddr = 0;
-
-    ret = fd_write_vmcore(&phdr, sizeof(Elf32_Phdr), s);
-    if (ret < 0) {
-        error_setg_errno(errp, -ret,
-                         "dump: failed to write program header table");
-    }
+    memset(phdr, 0, sizeof(*phdr));
+    phdr->p_type = cpu_to_dump32(s, PT_NOTE);
+    phdr->p_offset = cpu_to_dump32(s, s->note_offset);
+    phdr->p_paddr = 0;
+    phdr->p_filesz = cpu_to_dump32(s, s->note_size);
+    phdr->p_memsz = cpu_to_dump32(s, s->note_size);
+    phdr->p_vaddr = 0;
 }
 
 static void write_elf32_notes(WriteCoreDumpFunction f, DumpState *s,
@@ -348,6 +330,32 @@ static void write_elf32_notes(WriteCoreDumpFunction f, DumpState *s,
     write_guest_note(f, s, errp);
 }
 
+static void write_elf_phdr_note(DumpState *s, Error **errp)
+{
+    ERRP_GUARD();
+    Elf32_Phdr phdr32;
+    Elf64_Phdr phdr64;
+    void *phdr;
+    size_t size;
+    int ret;
+
+    if (dump_is_64bit(s)) {
+        write_elf64_phdr_note(s, &phdr64);
+        size = sizeof(phdr64);
+        phdr = &phdr64;
+    } else {
+        write_elf32_phdr_note(s, &phdr32);
+        size = sizeof(phdr32);
+        phdr = &phdr32;
+    }
+
+    ret = fd_write_vmcore(phdr, size, s);
+    if (ret < 0) {
+        error_setg_errno(errp, -ret,
+                         "dump: failed to write program header table");
+    }
+}
+
 static void write_elf_section(DumpState *s, int type, Error **errp)
 {
     Elf32_Shdr shdr32;
@@ -541,13 +549,13 @@ static void dump_begin(DumpState *s, Error **errp)
         return;
     }
 
-    if (dump_is_64bit(s)) {
-        /* write PT_NOTE to vmcore */
-        write_elf64_note(s, errp);
-        if (*errp) {
-            return;
-        }
+    /* write PT_NOTE to vmcore */
+    write_elf_phdr_note(s, errp);
+    if (*errp) {
+        return;
+    }
 
+    if (dump_is_64bit(s)) {
         /* write all PT_LOAD to vmcore */
         write_elf_loads(s, errp);
         if (*errp) {
@@ -568,12 +576,6 @@ static void dump_begin(DumpState *s, Error **errp)
             return;
         }
     } else {
-        /* write PT_NOTE to vmcore */
-        write_elf32_note(s, errp);
-        if (*errp) {
-            return;
-        }
-
         /* write all PT_LOAD to vmcore */
         write_elf_loads(s, errp);
         if (*errp) {
-- 
2.32.0

Re: [PATCH v2 7/9] dump: Consolidate phdr note writes

[Richard Henderson]

On 3/10/22 03:08, Janosch Frank wrote:
> There's no need to have two write functions. Let's rather have two
> functions that set the data for elf 32/64 and then write it in a
> common function.
> 
> Signed-off-by: Janosch Frank<frankja@linux.ibm.com>
> ---
>   dump/dump.c | 94 +++++++++++++++++++++++++++--------------------------
>   1 file changed, 48 insertions(+), 46 deletions(-)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~

[PATCH v2 8/9] dump: Cleanup dump_begin write functions

[Janosch Frank]

There's no need to have a gigantic if in there let's move the elf
32/64 bit logic into the section, segment or note code.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
---
 dump/dump.c | 42 +++++++++++-------------------------------
 1 file changed, 11 insertions(+), 31 deletions(-)

diff --git a/dump/dump.c b/dump/dump.c
index 1294673444..5542adf7b8 100644
--- a/dump/dump.c
+++ b/dump/dump.c
@@ -555,46 +555,26 @@ static void dump_begin(DumpState *s, Error **errp)
         return;
     }
 
-    if (dump_is_64bit(s)) {
-        /* write all PT_LOAD to vmcore */
-        write_elf_loads(s, errp);
+    /* write all PT_LOAD to vmcore */
+    write_elf_loads(s, errp);
+    if (*errp) {
+        return;
+    }
+
+    /* write section to vmcore */
+    if (s->shdr_num) {
+        write_elf_section(s, 1, errp);
         if (*errp) {
             return;
         }
+    }
 
-        /* write section to vmcore */
-        if (s->shdr_num) {
-            write_elf_section(s, 1, errp);
-            if (*errp) {
-                return;
-            }
-        }
-
+    if (dump_is_64bit(s)) {
         /* write notes to vmcore */
         write_elf64_notes(fd_write_vmcore, s, errp);
-        if (*errp) {
-            return;
-        }
     } else {
-        /* write all PT_LOAD to vmcore */
-        write_elf_loads(s, errp);
-        if (*errp) {
-            return;
-        }
-
-        /* write section to vmcore */
-        if (s->shdr_num) {
-            write_elf_section(s, 0, errp);
-            if (*errp) {
-                return;
-            }
-        }
-
         /* write notes to vmcore */
         write_elf32_notes(fd_write_vmcore, s, errp);
-        if (*errp) {
-            return;
-        }
     }
 }
 
-- 
2.32.0

Re: [PATCH v2 8/9] dump: Cleanup dump_begin write functions

[Richard Henderson]

On 3/10/22 03:08, Janosch Frank wrote:
> There's no need to have a gigantic if in there let's move the elf
> 32/64 bit logic into the section, segment or note code.
> 
> Signed-off-by: Janosch Frank<frankja@linux.ibm.com>
> ---
>   dump/dump.c | 42 +++++++++++-------------------------------
>   1 file changed, 11 insertions(+), 31 deletions(-)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~

[PATCH v2 9/9] dump: Consolidate elf note function

[Janosch Frank]

Just like with the other write functions let's move the 32/64 bit elf
handling to a function to improve readability.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
---
 dump/dump.c | 23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/dump/dump.c b/dump/dump.c
index 5542adf7b8..ae8ec527de 100644
--- a/dump/dump.c
+++ b/dump/dump.c
@@ -510,6 +510,20 @@ static void write_elf_loads(DumpState *s, Error **errp)
     }
 }
 
+static void write_elf_notes(DumpState *s, Error **errp)
+{
+    ERRP_GUARD();
+
+    if (dump_is_64bit(s)) {
+        write_elf64_notes(fd_write_vmcore, s, errp);
+    } else {
+        write_elf32_notes(fd_write_vmcore, s, errp);
+    }
+    if (*errp) {
+        return;
+    }
+}
+
 /* write elf header, PT_NOTE and elf note to vmcore. */
 static void dump_begin(DumpState *s, Error **errp)
 {
@@ -569,13 +583,8 @@ static void dump_begin(DumpState *s, Error **errp)
         }
     }
 
-    if (dump_is_64bit(s)) {
-        /* write notes to vmcore */
-        write_elf64_notes(fd_write_vmcore, s, errp);
-    } else {
-        /* write notes to vmcore */
-        write_elf32_notes(fd_write_vmcore, s, errp);
-    }
+    /* write notes to vmcore */
+    write_elf_notes(s, errp);
 }
 
 static int get_next_block(DumpState *s, GuestPhysBlock *block)
-- 
2.32.0

Re: [PATCH v2 9/9] dump: Consolidate elf note function

[Richard Henderson]

On 3/10/22 03:08, Janosch Frank wrote:
> +static void write_elf_notes(DumpState *s, Error **errp)
> +{
> +    ERRP_GUARD();
> +
> +    if (dump_is_64bit(s)) {
> +        write_elf64_notes(fd_write_vmcore, s, errp);
> +    } else {
> +        write_elf32_notes(fd_write_vmcore, s, errp);
> +    }
> +    if (*errp) {
> +        return;
> +    }
> +}

Are you anticipating adding more code to this function?
Otherwise the early return, and the guard are useless.


r~