On Mon, Feb 28, 2022 at 11:04:47AM +0530, Maninder Singh wrote:

with commit '82b37e632513 ("kallsyms: print module name in %ps/S
case when KALLSYMS is disabled"), module name printing was enhanced.

As per suggestion from Petr Mladek [off-list ref], covering
other flavours also to print build id also.

for %pB no change as it needs to know symbol name to adjust address
value which can't be done without KALLSYMS.

original output with KALLSYMS:
[8.842129] ps function_1 [crash]
[8.842735] pS function_1+0x4/0x2c [crash]
[8.842890] pSb function_1+0x4/0x2c [crash b367e79021b9f3b0172f9a36d4261c1f528ca1b3]
[8.843175] pB function_1+0x4/0x2c [crash]
[8.843362] pBb function_1+0x4/0x2c [crash b367e79021b9f3b0172f9a36d4261c1f528ca1b3]

original output without KALLSYMS:
[12.487424] ps 0xffff800000eb008c
[12.487598] pS 0xffff800000eb008c
[12.487723] pSb 0xffff800000eb008c
[12.487850] pB 0xffff800000eb008c
[12.487967] pBb 0xffff800000eb008c

With patched kernel without KALLSYMS:
[9.205207] ps 0xffff800000eb008c [crash]
[9.205564] pS 0xffff800000eb0000+0x8c [crash]
[9.205757] pSb 0xffff800000eb0000+0x8c [crash b367e79021b9f3b0172f9a36d4261c1f528ca1b3]
[9.206066] pB 0xffff800000eb0000+0x8c [crash]
[9.206257] pBb 0xffff800000eb0000+0x8c [crash b367e79021b9f3b0172f9a36d4261c1f528ca1b3]

...

+static int sprint_module_info(char *buf, char *end, unsigned long value,
+			     const char *fmt)
+{
+	struct module *mod;
+	unsigned long offset = 1;
+	unsigned long base;

+	int ret = 0;

This is hard to find if it's not close to the first use.
Since you are using positive numbers...

+	const char *modname;
+	int modbuildid = 0;
+	int len;
+#if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID)
+	const unsigned char *buildid = NULL;
+#endif
+
+	if (is_ksym_addr(value))
+		return 0;

+	if (*fmt == 'B' && fmt[1] == 'b')
+		modbuildid = 1;
+	else if (*fmt == 'S' && (fmt[1] == 'b' || (fmt[1] == 'R' && fmt[2] == 'b')))

Why not to split to two conditionals? Would be easier to get,

+		modbuildid = 1;
+	else if (*fmt != 's') {

These all are inconsistent, please switch to fmt[0].

+		/*
+		 * do nothing.
+		 */
+	} else
+		offset = 0;
+
+	preempt_disable();
+	mod = __module_address(value);
+	if (mod) {
+		ret = 1;
+		modname = mod->name;
+#if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID)
+		if (modbuildid)
+			buildid = mod->build_id;
+#endif
+		if (offset) {
+			base = (unsigned long)mod->core_layout.base;
+			offset = value - base;
+		}
+	}
+
+	preempt_enable();

+	if (!ret)

This looks a bit strange, but okay, I'm not familiar with the function of this
code.

+		return 0;
+
+	/* address belongs to module */
+	if (offset)
+		len = sprintf(buf, "0x%lx+0x%lx", base, offset);
+	else
+		len = sprintf(buf, "0x%lx", value);
+
+	len += sprintf(buf + len, " [%s", modname);
+#if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID)
+	if (modbuildid && buildid) {
+		/* build ID should match length of sprintf */
+		static_assert(sizeof(typeof_member(struct module, build_id)) == 20);
+		len += sprintf(buf + len, " %20phN", buildid);
+	}
+#endif
+	len += sprintf(buf + len, "]");
+
+	return len;
+}

-- 
With Best Regards,
Andy Shevchenko