10:26 p.m.
On x86-64, the v4 patch of updating crash gdb-10.1 has some regression
issues.
Issue 1: Some vmcores will segfault the updated crash:
gdb_interface.c:gdb_set_crash_scope:request is not initialized, so
request.fp may be an invalid address, then it will be passed to
gdb-10.1/gdb/symtab.c:gdb_command_funnel_1:set_stream(req->fp), and
segfaults crash.
So I initialize struct request to be {0}, and check if req->fp==0 before
set_stream.
Issue 2: Some vmcores and vmlinux make crash output "not match" message and
exit
with 1.
In kernel.c:verify_version, symbol "linux_banner" is used for version
check. In some kernel, linux_banner is in .data (type 'D'), some is in .rdata
(type 'R'). gdb-10.1 patch [1] removed .rdata from "const struct
section_to_type stt", thus type 'R' is lost and will be granded as type
'D' later,
so it cannot enter kernel.c:verify_version:"else if ((sp->type == 'R') ||
(sp->type == 'r')". In v4 patch, it appended (sp->type == 'D')
to this line, it looks type 'R' case is handled so far.
But when we have the real type 'D' linux_banner, it will enter the "else
if"
path as well. It is handled by function symbol_value, it is incorrect,
in fact we want it handled in else path by function get_symbol_data.
So I take the original "const struct section_to_type stt" array back and
removed
"(sp->type == 'D')".
When using this patch, please apply the gdb-10.1 v4 patch first, then
apply this patch to crash.
[1]
https://github.com/bminor/binutils-gdb/commit/49d9fd42acefc1c0ee282b58088...
---
gdb-10.1.patch | 36 +++++++++++++++++++++++++++++++++++-
gdb_interface.c | 2 +-
kernel.c | 2 +-
3 files changed, 37 insertions(+), 3 deletions(-)
diff --git a/gdb-10.1.patch b/gdb-10.1.patch
index 86ad3b4..7f37e02 100644
--- a/gdb-10.1.patch
+++ b/gdb-10.1.patch
@@ -717,7 +717,7 @@ diff -aurp -X diff_exclude gdb-10.1.orig/gdb/symtab.c
gdb-10.1/gdb/symtab.c
+{
+ struct symbol *sym;
+
-+ if (req->command != GNU_VERSION && req->command != GNU_USER_PRINT_OPTION)
{
++ if (req->command != GNU_VERSION && req->command != GNU_USER_PRINT_OPTION
&& req->fp) {
+ (dynamic_cast<stdio_file *>gdb_stdout)->set_stream(req->fp);
+ (dynamic_cast<stdio_file *>gdb_stderr)->set_stream(req->fp);
+ }
@@ -1627,3 +1627,37 @@ diff -aurp -X diff_exclude gdb-10.1.orig/readline/readline/util.c
gdb-10.1/readl
_rl_tracefp = 0;
return r;
}
+diff -aurp -X diff_exclude gdb-10.1.orig/bfd/syms.c gdb-10.1/bfd/syms.c
+index cb25af1..79d6fdd 100644
+--- gdb-10.1.orig/bfd/syms.c
++++ gdb-10.1/bfd/syms.c
+@@ -570,10 +570,25 @@ struct section_to_type
+ adding entries. Since it is so short, a linear search is used. */
+ static const struct section_to_type stt[] =
+ {
+- {".drectve", 'i'}, /* MSVC's .drective section */
+- {".edata", 'e'}, /* MSVC's .edata (export) section */
+- {".idata", 'i'}, /* MSVC's .idata (import) section */
+- {".pdata", 'p'}, /* MSVC's .pdata (stack unwind) section */
++ {".bss", 'b'},
++ {"code", 't'}, /* MRI .text */
++ {".data", 'd'},
++ {"*DEBUG*", 'N'},
++ {".debug", 'N'}, /* MSVC's .debug (non-standard
debug syms) */
++ {".drectve", 'i'}, /* MSVC's .drective section */
++ {".edata", 'e'}, /* MSVC's .edata (export) section
*/
++ {".fini", 't'}, /* ELF fini section */
++ {".idata", 'i'}, /* MSVC's .idata (import) section
*/
++ {".init", 't'}, /* ELF init section */
++ {".pdata", 'p'}, /* MSVC's .pdata (stack unwind)
section */
++ {".rdata", 'r'}, /* Read only data. */
++ {".rodata", 'r'}, /* Read only data. */
++ {".sbss", 's'}, /* Small BSS (uninitialized data). */
++ {".scommon", 'c'}, /* Small common. */
++ {".sdata", 'g'}, /* Small initialized data. */
++ {".text", 't'},
++ {"vars", 'd'}, /* MRI .data */
++ {"zerovars", 'b'}, /* MRI .bss */
+ {0, 0}
+ };
+
diff --git a/gdb_interface.c b/gdb_interface.c
index 5e0544b..3c7eb39 100644
--- a/gdb_interface.c
+++ b/gdb_interface.c
@@ -993,7 +993,7 @@ gdb_user_print_option_address(char *name)
int
gdb_set_crash_scope(ulong vaddr, char *arg)
{
- struct gnu_request request, *req = &request;
+ struct gnu_request request = {0}, *req = &request;
char name[BUFSIZE];
struct load_module *lm;
diff --git a/kernel.c b/kernel.c
index 360dd8c..e123f76 100644
--- a/kernel.c
+++ b/kernel.c
@@ -1056,7 +1056,7 @@ verify_version(void)
if (!(sp = symbol_search("linux_banner")))
error(FATAL, "linux_banner symbol does not exist?\n");
- else if ((sp->type == 'R') || (sp->type == 'r') || (sp->type ==
'D') ||
+ else if ((sp->type == 'R') || (sp->type == 'r') ||
(machine_type("ARM") && sp->type == 'T') ||
(machine_type("ARM64")))
linux_banner = symbol_value("linux_banner");
--
2.27.0