[Crash-utility] whatis: display full parameter name when symbol is function
Dave Anderson
anderson at redhat.com
Tue Mar 12 19:39:52 UTC 2013
----- Original Message -----
> Dave,
>
> Here is the patch which add feature to whatis that would display full parameter name
> when it detect the symbol is a function.
>
> And this patch already include previous fix for gdb_get_datatype,
> please help review it.
>
> Thanks,
> Lei
When I attempt a "whatis <text-symbol>" on a module function prior to
loading its module.ko file, your patch changes the command's behavior.
For example, without your patch, it shows that the gdb request failed:
crash> whatis call_transmit
whatis: gdb request failed: whatis call_transmit
crash>
So I load the module, and try again:
crash> mod -s sunrpc
MODULE NAME SIZE OBJECT FILE
ffffffffa0153ea0 sunrpc 255581 /lib/modules/3.7.9-104.fc17.x86_64/kernel/net/sunrpc/sunrpc.ko
crash> whatis call_transmit
void call_transmit(struct rpc_task *);
crash>
But with your patch, it fails quietly:
crash> whatis call_transmit
crash>
And while it works most of the time:
crash> mod -s sunrpc
MODULE NAME SIZE OBJECT FILE
ffffffffa0153ea0 sunrpc 255581 /lib/modules/3.7.9-104.fc17.x86_64/kernel/net/sunrpc/sunrpc.ko
crash> whatis call_transmit
void call_transmit(struct rpc_task * task);
crash>
if I do some other whatis/mod commands prior to it, I occasionally can get
this to happen:
crash> mod -s sunrpc
MODULE NAME SIZE OBJECT FILE
ffffffffa0153ea0 sunrpc 255581 /lib/modules/3.7.9-104.fc17.x86_64/kernel/net/sunrpc/sunrpc.ko
crash> whatis call_transmit
<segmentation violation in gdb>
crash>
The backtrace shows a SIGSEGV in your new gdb_function_nameargs() function:
Program received signal SIGSEGV, Segmentation fault.
gdb_function_nameargs (req=<optimized out>) at symtab.c:5263
5263 while ((BLOCK_FUNCTION(b) == NULL || block_inlined_p(b))
Missing separate debuginfos, use: debuginfo-install glibc-2.15-58.fc17.x86_64 ncurses-libs-5.9-4.20120204.fc17.x86_64 zlib-1.2.5-7.fc17.x86_64
(gdb) bt
#0 gdb_function_nameargs (req=<optimized out>) at symtab.c:5263
#1 gdb_command_funnel (req=req at entry=0xdd1e20) at symtab.c:4957
#2 0x00000000004d78c0 in gdb_interface (req=req at entry=0xdd1e20) at gdb_interface.c:397
#3 0x000000000050860d in whatis_variable (sp=<optimized out>) at symbols.c:6767
#4 0x0000000000508ab4 in cmd_whatis () at symbols.c:6199
#5 0x0000000000460694 in exec_command () at main.c:775
#6 0x0000000000521982 in exec_input_file () at cmdline.c:1407
#7 0x00000000004603e6 in is_input_file () at main.c:871
#8 exec_command () at main.c:782
#9 0x00000000004608ba in main_loop () at main.c:723
#10 0x000000000056ee49 in captured_command_loop (data=data at entry=0x0) at ./main.c:228
#11 0x000000000056e28e in catch_errors (func=func at entry=0x56ee40 <captured_command_loop>,
func_args=func_args at entry=0x0, errstring=errstring at entry=0x882acb "", mask=mask at entry=6) at exceptions.c:531
#12 0x000000000056fad6 in captured_main (data=data at entry=0x7fffffffe430) at ./main.c:958
#13 0x000000000056e28e in catch_errors (func=func at entry=0x56ef20 <captured_main>,
func_args=func_args at entry=0x7fffffffe430, errstring=errstring at entry=0x882acb "", mask=mask at entry=6)
at exceptions.c:531
#14 0x000000000056fda4 in gdb_main (args=args at entry=0x7fffffffe430) at ./main.c:973
#15 0x000000000056fdde in gdb_main_entry (argc=<optimized out>, argv=argv at entry=0x7fffffffe588) at ./main.c:993
#16 0x00000000004d69d4 in gdb_main_loop (argc=<optimized out>, argc at entry=1, argv=argv at entry=0x7fffffffe588)
at gdb_interface.c:76
#17 0x000000000045eeff in main (argc=1, argv=0x7fffffffe588) at main.c:628
(gdb)
But unfortunately, it's not necessarily reproducible, even with the same set
of commands!
The backtrace above was from a live session, and now I can't seem to reproduce it.
But I'm guessing that block_for_pc_sect() returned a NULL "b" pointer.
Dave
>
> From 8ea80a2ddbd0ea524a715a5e188118c39a0ce311 Mon Sep 17 00:00:00
> 2001
> From: Lei Wen <leiwen at marvell.com>
> Date: Mon, 11 Mar 2013 10:34:15 +0800
> Subject: [PATCH] whatis: display full parameter name when symbol is
> function
>
> Signed-off-by: Lei Wen <leiwen at marvell.com>
> ---
> defs.h | 1 +
> gdb-7.3.1.patch | 77
> +++++++++++++++++++++++++++++++++++++++++++++++++++++++
> gdb_interface.c | 3 ++
> symbols.c | 50 +++++++++++++++++++++++++++++++++++-
> 4 files changed, 130 insertions(+), 1 deletions(-)
>
> diff --git a/defs.h b/defs.h
> index 1f693c3..1b31d1f 100755
> --- a/defs.h
> +++ b/defs.h
> @@ -3685,6 +3685,7 @@ struct gnu_request {
> #define GNU_GET_SYMBOL_TYPE (15)
> #define GNU_USER_PRINT_OPTION (16)
> #define GNU_SET_CRASH_BLOCK (17)
> +#define GNU_FUNCTION_NAMEARGS (18)
> #define GNU_DEBUG_COMMAND (100)
> /*
> * GNU flags
> diff --git a/gdb-7.3.1.patch b/gdb-7.3.1.patch
> index a12d3d4..3b0f0d1 100644
> --- a/gdb-7.3.1.patch
> +++ b/gdb-7.3.1.patch
> @@ -1821,3 +1821,80 @@ diff -up gdb-7.3.1/gdb/psymtab.c.orig
> gdb-7.3.1/gdb/psymtab.c
> break;
>
> if (cur_sec == NULL)
> +--- gdb-7.3.1/gdb/symtab.c.orig
> ++++ gdb-7.3.1/gdb/symtab.c
> +@@ -4848,6 +4848,7 @@ static void gdb_get_symbol_type(struct
> gnu_request *);
> + static void gdb_command_exists(struct gnu_request *);
> + static void gdb_debug_command(struct gnu_request *);
> + static void gdb_function_numargs(struct gnu_request *);
> ++static void gdb_function_nameargs(struct gnu_request *);
> + static void gdb_add_symbol_file(struct gnu_request *);
> + static void gdb_delete_symbol_file(struct gnu_request *);
> + static void gdb_patch_symbol_values(struct gnu_request *);
> +@@ -4952,6 +4953,10 @@ gdb_command_funnel(struct gnu_request *req)
> + gdb_set_crash_block(req);
> + break;
> +
> ++ case GNU_FUNCTION_NAMEARGS:
> ++ gdb_function_nameargs(req);
> ++ break;
> ++
> + default:
> + req->flags |= GNU_COMMAND_FAILED;
> + break;
> +@@ -5054,8 +5059,9 @@ gdb_get_datatype(struct gnu_request *req)
> + if (gdb_CRASHDEBUG(2))
> + console("expr->elts[0].opcode: OP_VAR_VALUE\n");
> + type = expr->elts[2].symbol->type;
> ++ req->typecode = TYPE_CODE(type);
> ++ req->length = TYPE_LENGTH(type);
> + if (TYPE_CODE(type) == TYPE_CODE_ENUM) {
> +- req->typecode = TYPE_CODE(type);
> + req->value = SYMBOL_VALUE(expr->elts[2].symbol);
> + req->tagname = TYPE_TAG_NAME(type);
> + if (!req->tagname) {
> +@@ -5243,6 +5249,44 @@ gdb_function_numargs(struct gnu_request *req)
> + req->value = (ulong)TYPE_NFIELDS(sym->type);
> + }
> +
> ++static void
> ++gdb_function_nameargs(struct gnu_request *req)
> ++{
> ++ struct block *b;
> ++ struct dict_iterator iter;
> ++ struct symbol *sym = NULL;
> ++ int len;
> ++ char *buf = req->buf;
> ++
> ++ b = block_for_pc_sect(req->pc, find_pc_mapped_section(req->pc));
> ++ /* Get the lexical block, which is not a inline function */
> ++ while ((BLOCK_FUNCTION(b) == NULL || block_inlined_p(b))
> ++ && BLOCK_SUPERBLOCK(b) != NULL)
> ++ b = BLOCK_SUPERBLOCK(b);
> ++
> ++ ALL_BLOCK_SYMBOLS (b, iter, sym)
> ++ {
> ++ if (!SYMBOL_IS_ARGUMENT (sym))
> ++ continue;
> ++
> ++ if (*SYMBOL_LINKAGE_NAME (sym))
> ++ {
> ++ struct symbol *nsym;
> ++
> ++ nsym = lookup_symbol (SYMBOL_LINKAGE_NAME (sym),
> ++ b, VAR_DOMAIN, NULL);
> ++ gdb_assert (nsym != NULL);
> ++ if (SYMBOL_CLASS (nsym) != LOC_REGISTER
> ++ || SYMBOL_IS_ARGUMENT (nsym))
> ++ sym = nsym;
> ++ }
> ++
> ++ len = strlen(SYMBOL_PRINT_NAME(sym));
> ++ sprintf(buf, "%s,", SYMBOL_PRINT_NAME(sym));
> ++ buf += len + 1;
> ++ }
> ++}
> ++
> + struct load_module *gdb_current_load_module = NULL;
> +
> + static void
> diff --git a/gdb_interface.c b/gdb_interface.c
> index afc197c..a460ea8 100755
> --- a/gdb_interface.c
> +++ b/gdb_interface.c
> @@ -590,6 +590,9 @@ gdb_command_string(int cmd, char *buf, int live)
> case GNU_SET_CRASH_BLOCK:
> sprintf(buf, "GNU_SET_CRASH_BLOCK");
> break;
> + case GNU_FUNCTION_NAMEARGS:
> + sprintf(buf, "GNU_FUNCTION_NAMEARGS");
> + break;
> case 0:
> buf[0] = NULLCHAR;
> break;
> diff --git a/symbols.c b/symbols.c
> index 4fb397c..b38a2a3 100755
> --- a/symbols.c
> +++ b/symbols.c
> @@ -6660,18 +6660,62 @@ whatis_datatype(char *st, ulong flags, FILE
> *ofp)
> }
>
> /*
> + * add the function argument to the function type showing
> + * The arg name input is seperated by comma
> + */
> +static void
> +add_function_name(char *argnames, char *func)
> +{
> + char *arg, *seperator, *tmp;
> +
> + tmp = func;
> + for (arg = strtok(argnames, ","); arg; ) {
> + seperator = strstr(tmp, ",");
> + if (!seperator)
> + seperator= strrchr(func, ')');
> +
> + shift_string_right(seperator, strlen(arg) + 1);
> + BCOPY(arg, seperator + 1, strlen(arg));
> + tmp = seperator + 2 + strlen(arg);
> + arg = strtok(NULL, ",");
> + }
> +}
> +
> +/*
> * Scan the symbol file for a variable declaration.
> */
> static void
> whatis_variable(struct syment *sp)
> {
> + struct datatype_member datatype_member, *dm;
> + struct gnu_request *req;
> + int ret;
> char *p1;
> char buf[BUFSIZE];
>
> + dm = &datatype_member;
> + strcpy(buf, sp->name);
> + if (!arg_to_datatype(buf, dm, RETURN_ON_ERROR|DATATYPE_QUERY))
> + return FALSE;
> +
> open_tmpfile();
> sprintf(buf, "whatis %s", sp->name);
> - if (!gdb_pass_through(buf, fp, GNU_RETURN_ON_ERROR)) {
> +
> + req = (struct gnu_request *)GETBUF(sizeof(struct gnu_request));
> + req->buf = GETBUF(BUFSIZE);
> +
> + ret = gdb_pass_through(buf, fp, GNU_RETURN_ON_ERROR);
> + if (ret && dm->type == FUNCTION) {
> + req->command = GNU_FUNCTION_NAMEARGS;
> + req->flags |= GNU_RETURN_ON_ERROR;
> + req->pc = symbol_value(sp->name);
> +
> + gdb_interface(req);
> + }
> + if (!ret || req->flags & GNU_COMMAND_FAILED) {
> close_tmpfile();
> + FREEBUF(req->buf);
> + FREEBUF(req);
> error(FATAL, "gdb request failed: whatis %s\n",
> sp->name);
> }
>
> @@ -6693,6 +6737,7 @@ whatis_variable(struct syment *sp)
> if (index(buf, '(') == rindex(buf, '(')) {
> shift_string_right(p1, strlen(sp->name));
> BCOPY(sp->name, p1, strlen(sp->name));
> + add_function_name(req->buf, p1 + strlen(sp->name));
> } else {
> p1 = strstr(buf, ")");
> shift_string_right(p1, strlen(sp->name));
> @@ -6705,6 +6750,9 @@ whatis_variable(struct syment *sp)
> fprintf(fp, "%s%s%s;\n", p1, LASTCHAR(p1) == '*' ?
> "":" ",
> sp->name);
> }
> +
> + FREEBUF(req->buf);
> + FREEBUF(req);
> }
>
> /*
> --
> 1.7.5.4
>
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