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-rw-r--r--target/linux/generic/backport-5.10/050-v5.16-04-mips-bpf-Add-JIT-workarounds-for-CPU-errata.patch120
1 files changed, 120 insertions, 0 deletions
diff --git a/target/linux/generic/backport-5.10/050-v5.16-04-mips-bpf-Add-JIT-workarounds-for-CPU-errata.patch b/target/linux/generic/backport-5.10/050-v5.16-04-mips-bpf-Add-JIT-workarounds-for-CPU-errata.patch
new file mode 100644
index 0000000000..63553ebe58
--- /dev/null
+++ b/target/linux/generic/backport-5.10/050-v5.16-04-mips-bpf-Add-JIT-workarounds-for-CPU-errata.patch
@@ -0,0 +1,120 @@
+From: Johan Almbladh <johan.almbladh@anyfinetworks.com>
+Date: Tue, 5 Oct 2021 18:54:06 +0200
+Subject: [PATCH] mips: bpf: Add JIT workarounds for CPU errata
+
+This patch adds workarounds for the following CPU errata to the MIPS
+eBPF JIT, if enabled in the kernel configuration.
+
+ - R10000 ll/sc weak ordering
+ - Loongson-3 ll/sc weak ordering
+ - Loongson-2F jump hang
+
+The Loongson-2F nop errata is implemented in uasm, which the JIT uses,
+so no additional mitigations are needed for that.
+
+Signed-off-by: Johan Almbladh <johan.almbladh@anyfinetworks.com>
+Reviewed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
+---
+
+--- a/arch/mips/net/bpf_jit_comp.c
++++ b/arch/mips/net/bpf_jit_comp.c
+@@ -404,6 +404,7 @@ void emit_alu_r(struct jit_context *ctx,
+ /* Atomic read-modify-write (32-bit) */
+ void emit_atomic_r(struct jit_context *ctx, u8 dst, u8 src, s16 off, u8 code)
+ {
++ LLSC_sync(ctx);
+ emit(ctx, ll, MIPS_R_T9, off, dst);
+ switch (code) {
+ case BPF_ADD:
+@@ -420,18 +421,19 @@ void emit_atomic_r(struct jit_context *c
+ break;
+ }
+ emit(ctx, sc, MIPS_R_T8, off, dst);
+- emit(ctx, beqz, MIPS_R_T8, -16);
++ emit(ctx, LLSC_beqz, MIPS_R_T8, -16 - LLSC_offset);
+ emit(ctx, nop); /* Delay slot */
+ }
+
+ /* Atomic compare-and-exchange (32-bit) */
+ void emit_cmpxchg_r(struct jit_context *ctx, u8 dst, u8 src, u8 res, s16 off)
+ {
++ LLSC_sync(ctx);
+ emit(ctx, ll, MIPS_R_T9, off, dst);
+ emit(ctx, bne, MIPS_R_T9, res, 12);
+ emit(ctx, move, MIPS_R_T8, src); /* Delay slot */
+ emit(ctx, sc, MIPS_R_T8, off, dst);
+- emit(ctx, beqz, MIPS_R_T8, -20);
++ emit(ctx, LLSC_beqz, MIPS_R_T8, -20 - LLSC_offset);
+ emit(ctx, move, res, MIPS_R_T9); /* Delay slot */
+ clobber_reg(ctx, res);
+ }
+--- a/arch/mips/net/bpf_jit_comp.h
++++ b/arch/mips/net/bpf_jit_comp.h
+@@ -87,7 +87,7 @@ struct jit_context {
+ };
+
+ /* Emit the instruction if the JIT memory space has been allocated */
+-#define emit(ctx, func, ...) \
++#define __emit(ctx, func, ...) \
+ do { \
+ if ((ctx)->target != NULL) { \
+ u32 *p = &(ctx)->target[ctx->jit_index]; \
+@@ -95,6 +95,30 @@ do { \
+ } \
+ (ctx)->jit_index++; \
+ } while (0)
++#define emit(...) __emit(__VA_ARGS__)
++
++/* Workaround for R10000 ll/sc errata */
++#ifdef CONFIG_WAR_R10000
++#define LLSC_beqz beqzl
++#else
++#define LLSC_beqz beqz
++#endif
++
++/* Workaround for Loongson-3 ll/sc errata */
++#ifdef CONFIG_CPU_LOONGSON3_WORKAROUNDS
++#define LLSC_sync(ctx) emit(ctx, sync, 0)
++#define LLSC_offset 4
++#else
++#define LLSC_sync(ctx)
++#define LLSC_offset 0
++#endif
++
++/* Workaround for Loongson-2F jump errata */
++#ifdef CONFIG_CPU_JUMP_WORKAROUNDS
++#define JALR_MASK 0xffffffffcfffffffULL
++#else
++#define JALR_MASK (~0ULL)
++#endif
+
+ /*
+ * Mark a BPF register as accessed, it needs to be
+--- a/arch/mips/net/bpf_jit_comp64.c
++++ b/arch/mips/net/bpf_jit_comp64.c
+@@ -375,6 +375,7 @@ static void emit_atomic_r64(struct jit_c
+ u8 t1 = MIPS_R_T6;
+ u8 t2 = MIPS_R_T7;
+
++ LLSC_sync(ctx);
+ emit(ctx, lld, t1, off, dst);
+ switch (code) {
+ case BPF_ADD:
+@@ -391,7 +392,7 @@ static void emit_atomic_r64(struct jit_c
+ break;
+ }
+ emit(ctx, scd, t2, off, dst);
+- emit(ctx, beqz, t2, -16);
++ emit(ctx, LLSC_beqz, t2, -16 - LLSC_offset);
+ emit(ctx, nop); /* Delay slot */
+ }
+
+@@ -414,7 +415,7 @@ static int emit_call(struct jit_context
+ push_regs(ctx, ctx->clobbered & JIT_CALLER_REGS, 0, 0);
+
+ /* Emit function call */
+- emit_mov_i64(ctx, tmp, addr);
++ emit_mov_i64(ctx, tmp, addr & JALR_MASK);
+ emit(ctx, jalr, MIPS_R_RA, tmp);
+ emit(ctx, nop); /* Delay slot */
+