[PATCH v4 2/2] arm64: rust: Enable Rust support for AArch64
Stephen Boyd
sboyd at kernel.org
Mon Oct 23 17:57:59 PDT 2023
Quoting Boqun Feng (2023-10-20 11:33:10)
> On Fri, Oct 20, 2023 at 07:21:08PM +0200, Andrew Lunn wrote:
> > > +``arm64`` Maintained Little Endian only.
> >
> > This question is just out of curiosity, not the patchset itself.
> >
> > What is missing to make big endian work?
> >
>
> FWIW, I tried the following:
>
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 8784284988e5..b697c2d7da68 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -227,7 +227,7 @@ config ARM64
> select HAVE_FUNCTION_ARG_ACCESS_API
> select MMU_GATHER_RCU_TABLE_FREE
> select HAVE_RSEQ
> - select HAVE_RUST if CPU_LITTLE_ENDIAN
> + select HAVE_RUST
> select HAVE_STACKPROTECTOR
> select HAVE_SYSCALL_TRACEPOINTS
> select HAVE_KPROBES
> diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
> index 4562a8173e90..4621f1e00e06 100644
> --- a/arch/arm64/Makefile
> +++ b/arch/arm64/Makefile
> @@ -41,7 +41,11 @@ KBUILD_CFLAGS += -mgeneral-regs-only \
> KBUILD_CFLAGS += $(call cc-disable-warning, psabi)
> KBUILD_AFLAGS += $(compat_vdso)
>
> +ifeq ($(CONFIG_CPU_BIG_ENDIAN), y)
> +KBUILD_RUSTFLAGS += --target aarch64_be-unknown-linux-gnu -C target-feature="-neon"
> +else
> KBUILD_RUSTFLAGS += --target aarch64-unknown-none -C target-feature="-neon"
> +endif
>
> KBUILD_CFLAGS += $(call cc-option,-mabi=lp64)
> KBUILD_AFLAGS += $(call cc-option,-mabi=lp64)
>
> and ran the following kunit command (it will run a few tests in a qemu
> emulated VM):
>
> ./tools/testing/kunit/kunit.py run --make_options LLVM=1 --arch arm64 --kconfig_add CONFIG_RUST=y --kconfig_add CONFIG_CPU_BIG_ENDIAN=y
>
> The kernel was built successfully, and all Rust related tests passed.
>
> Of course this doesn't mean a lot, we still need people with deep
> Rust compiler knowledge to confirm whether the support is completed or
> not. But I think if people want to do experiments, the tool is there.
>
> P.S. An unrelated topic: I found a few clk related tests (in
> drivers/clk/clk-gate_test.c IIUC) don't pass (mostly due to that the
> expected values don't handle big endian), a sample failure output:
>
> [11:13:26] # clk_gate_test_enable: EXPECTATION FAILED at drivers/clk/clk-gate_test.c:169
> [11:13:26] Expected enable_val == ctx->fake_reg, but
> [11:13:26] enable_val == 32 (0x20)
> [11:13:26] ctx->fake_reg == 536870912 (0x20000000)
> [11:13:26] clk_unregister: unregistering prepared clock: test_gate
> [11:13:26] clk_unregister: unregistering prepared clock: test_parent
> [11:13:26] [FAILED] clk_gate_test_enable
>
> (Cc clk folks)
>
Thanks for the report! We should treat it as an __le32 for now. I'll
have to add tests for the big endian flag as well. Does this fix it?
---8<----
diff --git a/drivers/clk/clk-gate_test.c b/drivers/clk/clk-gate_test.c
index e136aaad48bf..c96d93b19ddf 100644
--- a/drivers/clk/clk-gate_test.c
+++ b/drivers/clk/clk-gate_test.c
@@ -131,7 +131,7 @@ struct clk_gate_test_context {
void __iomem *fake_mem;
struct clk_hw *hw;
struct clk_hw *parent;
- u32 fake_reg; /* Keep at end, KASAN can detect out of bounds */
+ __le32 fake_reg; /* Keep at end, KASAN can detect out of bounds */
};
static struct clk_gate_test_context *clk_gate_test_alloc_ctx(struct kunit *test)
@@ -166,7 +166,7 @@ static void clk_gate_test_enable(struct kunit *test)
KUNIT_ASSERT_EQ(test, clk_prepare_enable(clk), 0);
- KUNIT_EXPECT_EQ(test, enable_val, ctx->fake_reg);
+ KUNIT_EXPECT_EQ(test, enable_val, le32_to_cpu(ctx->fake_reg));
KUNIT_EXPECT_TRUE(test, clk_hw_is_enabled(hw));
KUNIT_EXPECT_TRUE(test, clk_hw_is_prepared(hw));
KUNIT_EXPECT_TRUE(test, clk_hw_is_enabled(parent));
@@ -183,10 +183,10 @@ static void clk_gate_test_disable(struct kunit *test)
u32 disable_val = 0;
KUNIT_ASSERT_EQ(test, clk_prepare_enable(clk), 0);
- KUNIT_ASSERT_EQ(test, enable_val, ctx->fake_reg);
+ KUNIT_ASSERT_EQ(test, enable_val, le32_to_cpu(ctx->fake_reg));
clk_disable_unprepare(clk);
- KUNIT_EXPECT_EQ(test, disable_val, ctx->fake_reg);
+ KUNIT_EXPECT_EQ(test, disable_val, le32_to_cpu(ctx->fake_reg));
KUNIT_EXPECT_FALSE(test, clk_hw_is_enabled(hw));
KUNIT_EXPECT_FALSE(test, clk_hw_is_prepared(hw));
KUNIT_EXPECT_FALSE(test, clk_hw_is_enabled(parent));
@@ -246,7 +246,7 @@ static void clk_gate_test_invert_enable(struct kunit *test)
KUNIT_ASSERT_EQ(test, clk_prepare_enable(clk), 0);
- KUNIT_EXPECT_EQ(test, enable_val, ctx->fake_reg);
+ KUNIT_EXPECT_EQ(test, enable_val, le32_to_cpu(ctx->fake_reg));
KUNIT_EXPECT_TRUE(test, clk_hw_is_enabled(hw));
KUNIT_EXPECT_TRUE(test, clk_hw_is_prepared(hw));
KUNIT_EXPECT_TRUE(test, clk_hw_is_enabled(parent));
@@ -263,10 +263,10 @@ static void clk_gate_test_invert_disable(struct kunit *test)
u32 disable_val = BIT(15);
KUNIT_ASSERT_EQ(test, clk_prepare_enable(clk), 0);
- KUNIT_ASSERT_EQ(test, enable_val, ctx->fake_reg);
+ KUNIT_ASSERT_EQ(test, enable_val, le32_to_cpu(ctx->fake_reg));
clk_disable_unprepare(clk);
- KUNIT_EXPECT_EQ(test, disable_val, ctx->fake_reg);
+ KUNIT_EXPECT_EQ(test, disable_val, le32_to_cpu(ctx->fake_reg));
KUNIT_EXPECT_FALSE(test, clk_hw_is_enabled(hw));
KUNIT_EXPECT_FALSE(test, clk_hw_is_prepared(hw));
KUNIT_EXPECT_FALSE(test, clk_hw_is_enabled(parent));
@@ -290,7 +290,7 @@ static int clk_gate_test_invert_init(struct kunit *test)
2000000);
KUNIT_ASSERT_NOT_ERR_OR_NULL(test, parent);
- ctx->fake_reg = BIT(15); /* Default to off */
+ ctx->fake_reg = cpu_to_le32(BIT(15)); /* Default to off */
hw = clk_hw_register_gate_parent_hw(NULL, "test_gate", parent, 0,
ctx->fake_mem, 15,
CLK_GATE_SET_TO_DISABLE, NULL);
@@ -319,7 +319,7 @@ static void clk_gate_test_hiword_enable(struct kunit *test)
KUNIT_ASSERT_EQ(test, clk_prepare_enable(clk), 0);
- KUNIT_EXPECT_EQ(test, enable_val, ctx->fake_reg);
+ KUNIT_EXPECT_EQ(test, enable_val, le32_to_cpu(ctx->fake_reg));
KUNIT_EXPECT_TRUE(test, clk_hw_is_enabled(hw));
KUNIT_EXPECT_TRUE(test, clk_hw_is_prepared(hw));
KUNIT_EXPECT_TRUE(test, clk_hw_is_enabled(parent));
@@ -336,10 +336,10 @@ static void clk_gate_test_hiword_disable(struct kunit *test)
u32 disable_val = BIT(9 + 16);
KUNIT_ASSERT_EQ(test, clk_prepare_enable(clk), 0);
- KUNIT_ASSERT_EQ(test, enable_val, ctx->fake_reg);
+ KUNIT_ASSERT_EQ(test, enable_val, le32_to_cpu(ctx->fake_reg));
clk_disable_unprepare(clk);
- KUNIT_EXPECT_EQ(test, disable_val, ctx->fake_reg);
+ KUNIT_EXPECT_EQ(test, disable_val, le32_to_cpu(ctx->fake_reg));
KUNIT_EXPECT_FALSE(test, clk_hw_is_enabled(hw));
KUNIT_EXPECT_FALSE(test, clk_hw_is_prepared(hw));
KUNIT_EXPECT_FALSE(test, clk_hw_is_enabled(parent));
@@ -387,7 +387,7 @@ static void clk_gate_test_is_enabled(struct kunit *test)
struct clk_gate_test_context *ctx;
ctx = clk_gate_test_alloc_ctx(test);
- ctx->fake_reg = BIT(7);
+ ctx->fake_reg = cpu_to_le32(BIT(7));
hw = clk_hw_register_gate(NULL, "test_gate", NULL, 0, ctx->fake_mem, 7,
0, NULL);
KUNIT_ASSERT_NOT_ERR_OR_NULL(test, hw);
@@ -402,7 +402,7 @@ static void clk_gate_test_is_disabled(struct kunit *test)
struct clk_gate_test_context *ctx;
ctx = clk_gate_test_alloc_ctx(test);
- ctx->fake_reg = BIT(4);
+ ctx->fake_reg = cpu_to_le32(BIT(4));
hw = clk_hw_register_gate(NULL, "test_gate", NULL, 0, ctx->fake_mem, 7,
0, NULL);
KUNIT_ASSERT_NOT_ERR_OR_NULL(test, hw);
@@ -417,7 +417,7 @@ static void clk_gate_test_is_enabled_inverted(struct kunit *test)
struct clk_gate_test_context *ctx;
ctx = clk_gate_test_alloc_ctx(test);
- ctx->fake_reg = BIT(31);
+ ctx->fake_reg = cpu_to_le32(BIT(31));
hw = clk_hw_register_gate(NULL, "test_gate", NULL, 0, ctx->fake_mem, 2,
CLK_GATE_SET_TO_DISABLE, NULL);
KUNIT_ASSERT_NOT_ERR_OR_NULL(test, hw);
@@ -432,7 +432,7 @@ static void clk_gate_test_is_disabled_inverted(struct kunit *test)
struct clk_gate_test_context *ctx;
ctx = clk_gate_test_alloc_ctx(test);
- ctx->fake_reg = BIT(29);
+ ctx->fake_reg = cpu_to_le32(BIT(29));
hw = clk_hw_register_gate(NULL, "test_gate", NULL, 0, ctx->fake_mem, 29,
CLK_GATE_SET_TO_DISABLE, NULL);
KUNIT_ASSERT_NOT_ERR_OR_NULL(test, hw);
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