netdev - [PATCH 2/7] mips: uasm: Add workaround for Loongson-2F nop CPU errata

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: <20211005165408.2305108-3-johan.almbladh@anyfinetworks.com>
Date:   Tue,  5 Oct 2021 18:54:03 +0200
From:   Johan Almbladh <johan.almbladh@...finetworks.com>
To:     ast@...nel.org, daniel@...earbox.net, andrii@...nel.org,
        paulburton@...nel.org
Cc:     kafai@...com, songliubraving@...com, yhs@...com,
        john.fastabend@...il.com, kpsingh@...nel.org,
        tsbogend@...ha.franken.de, chenhuacai@...nel.org,
        jiaxun.yang@...goat.com, yangtiezhu@...ngson.cn,
        tony.ambardar@...il.com, bpf@...r.kernel.org,
        linux-mips@...r.kernel.org, netdev@...r.kernel.org,
        Johan Almbladh <johan.almbladh@...finetworks.com>
Subject: [PATCH 2/7] mips: uasm: Add workaround for Loongson-2F nop CPU errata

This patch implements a workaround for the Loongson-2F nop in generated,
code, if the existing option CONFIG_CPU_NOP_WORKAROUND is set. Before,
the binutils option -mfix-loongson2f-nop was enabled, but no workaround
was done when emitting MIPS code. Now, the nop pseudo instruction is
emitted as "or ax,ax,zero" instead of the default "sll zero,zero,0". This
is consistent with the workaround implemented by binutils.

Link: https://sourceware.org/legacy-ml/binutils/2009-11/msg00387.html

Signed-off-by: Johan Almbladh <johan.almbladh@...finetworks.com>
---
 arch/mips/include/asm/uasm.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/mips/include/asm/uasm.h b/arch/mips/include/asm/uasm.h
index 5efa4e2dc9ab..296bcf31abb5 100644
--- a/arch/mips/include/asm/uasm.h
+++ b/arch/mips/include/asm/uasm.h
@@ -249,7 +249,11 @@ static inline void uasm_l##lb(struct uasm_label **lab, u32 *addr)	\
 #define uasm_i_bnezl(buf, rs, off) uasm_i_bnel(buf, rs, 0, off)
 #define uasm_i_ehb(buf) uasm_i_sll(buf, 0, 0, 3)
 #define uasm_i_move(buf, a, b) UASM_i_ADDU(buf, a, 0, b)
+#ifdef CONFIG_CPU_NOP_WORKAROUNDS
+#define uasm_i_nop(buf) uasm_i_or(buf, 1, 1, 0)
+#else
 #define uasm_i_nop(buf) uasm_i_sll(buf, 0, 0, 0)
+#endif
 #define uasm_i_ssnop(buf) uasm_i_sll(buf, 0, 0, 1)
 
 static inline void uasm_i_drotr_safe(u32 **p, unsigned int a1,
-- 
2.30.2