linux-kernel - [PATCH 5/5] kdb: Get rid of confusing diag msg from "rd" if current task has no regs

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20191109111624.5.I121f4c6f0c19266200bf6ef003de78841e5bfc3d@changeid>
Date:   Sat,  9 Nov 2019 11:16:44 -0800
From:   Douglas Anderson <dianders@...omium.org>
To:     Paul Burton <paul.burton@...s.com>,
        Jason Wessel <jason.wessel@...driver.com>,
        Daniel Thompson <daniel.thompson@...aro.org>
Cc:     qiaochong@...ngson.cn, kgdb-bugreport@...ts.sourceforge.net,
        ralf@...ux-mips.org, Douglas Anderson <dianders@...omium.org>,
        Chuhong Yuan <hslester96@...il.com>,
        Christophe Leroy <christophe.leroy@....fr>,
        linux-kernel@...r.kernel.org,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>,
        Nicholas Mc Guire <hofrat@...dl.org>,
        Dan Carpenter <dan.carpenter@...cle.com>
Subject: [PATCH 5/5] kdb: Get rid of confusing diag msg from "rd" if current task has no regs

If you switch to a sleeping task with the "pid" command and then type
"rd", kdb tells you this:

  No current kdb registers.  You may need to select another task
  diag: -17: Invalid register name

The first message makes sense, but not the second.  Fix it by just
returning 0 after commands accessing the current registers finish if
we've already printed the "No current kdb registers" error.

While fixing kdb_rd(), change the function to use "if" rather than
"ifdef".  It cleans the function up a bit and any modern compiler will
have no trouble handling still producing good code.

Signed-off-by: Douglas Anderson <dianders@...omium.org>
---

 kernel/debug/kdb/kdb_main.c | 28 +++++++++++++---------------
 1 file changed, 13 insertions(+), 15 deletions(-)

diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
index ba12e9f4661e..b22292b649c4 100644
--- a/kernel/debug/kdb/kdb_main.c
+++ b/kernel/debug/kdb/kdb_main.c
@@ -543,9 +543,8 @@ int kdbgetaddrarg(int argc, const char **argv, int *nextarg,
 		if (diag)
 			return diag;
 	} else if (symname[0] == '%') {
-		diag = kdb_check_regs();
-		if (diag)
-			return diag;
+		if (kdb_check_regs())
+			return 0;
 		/* Implement register values with % at a later time as it is
 		 * arch optional.
 		 */
@@ -1836,8 +1835,7 @@ static int kdb_go(int argc, const char **argv)
  */
 static int kdb_rd(int argc, const char **argv)
 {
-	int len = kdb_check_regs();
-#if DBG_MAX_REG_NUM > 0
+	int len = 0;
 	int i;
 	char *rname;
 	int rsize;
@@ -1846,8 +1844,14 @@ static int kdb_rd(int argc, const char **argv)
 	u16 reg16;
 	u8 reg8;
 
-	if (len)
-		return len;
+	if (kdb_check_regs())
+		return 0;
+
+	/* Fallback to Linux showregs() if we don't have DBG_MAX_REG_NUM */
+	if (DBG_MAX_REG_NUM <= 0) {
+		kdb_dumpregs(kdb_current_regs);
+		return 0;
+	}
 
 	for (i = 0; i < DBG_MAX_REG_NUM; i++) {
 		rsize = dbg_reg_def[i].size * 2;
@@ -1889,12 +1893,7 @@ static int kdb_rd(int argc, const char **argv)
 		}
 	}
 	kdb_printf("\n");
-#else
-	if (len)
-		return len;
 
-	kdb_dumpregs(kdb_current_regs);
-#endif
 	return 0;
 }
 
@@ -1928,9 +1927,8 @@ static int kdb_rm(int argc, const char **argv)
 	if (diag)
 		return diag;
 
-	diag = kdb_check_regs();
-	if (diag)
-		return diag;
+	if (kdb_check_regs())
+		return 0;
 
 	diag = KDB_BADREG;
 	for (i = 0; i < DBG_MAX_REG_NUM; i++) {
-- 
2.24.0.432.g9d3f5f5b63-goog