linux-kernel - [PATCH 3.16 278/294] MIPS: DEC: Avoid la pseudo-instruction in delay slots

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: <lsq.1510009382.428266682@decadent.org.uk>
Date:   Mon, 06 Nov 2017 23:03:02 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Ralf Baechle" <ralf@...ux-mips.org>,
        "Arnd Bergmann" <arnd@...db.de>
Subject: [PATCH 3.16 278/294] MIPS: DEC: Avoid la pseudo-instruction in
 delay slots

3.16.50-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Ralf Baechle <ralf@...ux-mips.org>

commit 3021773c7c3e75e20b693931a19362681e744ea9 upstream.

When expanding the la or dla pseudo-instruction in a delay slot the GNU
assembler will complain should the pseudo-instruction expand to multiple
actual instructions, since only the first of them will be in the delay
slot leading to the pseudo-instruction being only partially executed if
the branch is taken. Use of PTR_LA in the dec int-handler.S leads to
such warnings:

  arch/mips/dec/int-handler.S: Assembler messages:
  arch/mips/dec/int-handler.S:149: Warning: macro instruction expanded into multiple instructions in a branch delay slot
  arch/mips/dec/int-handler.S:198: Warning: macro instruction expanded into multiple instructions in a branch delay slot

Avoid this by open coding the PTR_LA macros.

Signed-off-by: Ralf Baechle <ralf@...ux-mips.org>
Signed-off-by: Arnd Bergmann <arnd@...db.de>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 arch/mips/dec/int-handler.S | 40 ++++++++++++++++++++++++++++++++++++++--
 1 file changed, 38 insertions(+), 2 deletions(-)

--- a/arch/mips/dec/int-handler.S
+++ b/arch/mips/dec/int-handler.S
@@ -146,7 +146,25 @@
 		/*
 		 * Find irq with highest priority
 		 */
-		 PTR_LA	t1,cpu_mask_nr_tbl
+		# open coded PTR_LA t1, cpu_mask_nr_tbl
+#if (_MIPS_SZPTR == 32)
+		# open coded la t1, cpu_mask_nr_tbl
+		lui	t1, %hi(cpu_mask_nr_tbl)
+		addiu	t1, %lo(cpu_mask_nr_tbl)
+
+#endif
+#if (_MIPS_SZPTR == 64)
+		# open coded dla t1, cpu_mask_nr_tbl
+		.set	push
+		.set	noat
+		lui	t1, %highest(cpu_mask_nr_tbl)
+		lui	AT, %hi(cpu_mask_nr_tbl)
+		daddiu	t1, t1, %higher(cpu_mask_nr_tbl)
+		daddiu	AT, AT, %lo(cpu_mask_nr_tbl)
+		dsll	t1, 32
+		daddu	t1, t1, AT
+		.set	pop
+#endif
 1:		lw	t2,(t1)
 		nop
 		and	t2,t0
@@ -195,7 +213,25 @@
 		/*
 		 * Find irq with highest priority
 		 */
-		 PTR_LA	t1,asic_mask_nr_tbl
+		# open coded PTR_LA t1,asic_mask_nr_tbl
+#if (_MIPS_SZPTR == 32)
+		# open coded la t1, asic_mask_nr_tbl
+		lui	t1, %hi(asic_mask_nr_tbl)
+		addiu	t1, %lo(asic_mask_nr_tbl)
+
+#endif
+#if (_MIPS_SZPTR == 64)
+		# open coded dla t1, asic_mask_nr_tbl
+		.set	push
+		.set	noat
+		lui	t1, %highest(asic_mask_nr_tbl)
+		lui	AT, %hi(asic_mask_nr_tbl)
+		daddiu	t1, t1, %higher(asic_mask_nr_tbl)
+		daddiu	AT, AT, %lo(asic_mask_nr_tbl)
+		dsll	t1, 32
+		daddu	t1, t1, AT
+		.set	pop
+#endif
 2:		lw	t2,(t1)
 		nop
 		and	t2,t0