kernel: backport a rewrite of the mips eBPF JIT implementation

[openwrt/openwrt.git] / target / linux / generic / backport-5.4 / 071-v5.16-01-mips-uasm-Add-workaround-for-Loongson-2F-nop-CPU-err.patch

diff --git a/target/linux/generic/backport-5.4/071-v5.16-01-mips-uasm-Add-workaround-for-Loongson-2F-nop-CPU-err.patch b/target/linux/generic/backport-5.4/071-v5.16-01-mips-uasm-Add-workaround-for-Loongson-2F-nop-CPU-err.patch
new file mode 100644 (file)
index 0000000..3a4d573
--- /dev/null
+++ b/target/linux/generic/backport-5.4/071-v5.16-01-mips-uasm-Add-workaround-for-Loongson-2F-nop-CPU-err.patch
@@ -0,0 +1,31 @@
+From: Johan Almbladh <johan.almbladh@anyfinetworks.com>
+Date: Tue, 5 Oct 2021 18:54:03 +0200
+Subject: [PATCH] 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@anyfinetworks.com>
+Reviewed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
+---
+
+--- 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 uas
+ #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,