kbuild: rust: keep Rust objects out of Clang LTO with inline helpersgrafted

Under `CONFIG_LTO_CLANG` + `CONFIG_RUST_INLINE_HELPERS`, one may hit
`objtool` errors such as:

    vmlinux.o: error: objtool: _R..._3Gsp4boot+0xd6a:
    can't find jump dest instruction at .text._R..._3Gsp4boot+0x1dfd

The reason is that in such builds, the Clang invocation that compiles
the combined Rust plus helpers bitcode emits LLVM bitcode (again) --
the final code generation happens in the linker's LTO step, which the
`-mllvm` trap options passed to Clang do not reach.

This, in turn, means that unreachable traps are missing, and the
impossible paths do not merely fallthrough to the next symbol, but past
the end of their own section, since LTO builds place each function in
its own section.

Thus filter `CC_FLAGS_LTO` out of the Clang invocation, so that it always
emits machine code directly, with the traps in place.

Assisted-by: LLM
Cc: Gary Guo <gary@garyguo.net>
Cc: Boqun Feng <boqun@kernel.org>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust")
Acked-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

1 files changed, 419 insertions, 0 deletions

diff --git a/drivers/edac/qcom_edac.c b/drivers/edac/qcom_edac.c
new file mode 100644
index 000000000..f3da9385c
--- /dev/null
+++ b/drivers/edac/qcom_edac.c
@@ -0,0 +1,419 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2018, The Linux Foundation. All rights reserved.
+ */
+
+#include <linux/edac.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/soc/qcom/llcc-qcom.h>
+
+#include "edac_mc.h"
+#include "edac_device.h"
+
+#define EDAC_LLCC                       "qcom_llcc"
+
+#define LLCC_ERP_PANIC_ON_UE            1
+
+#define TRP_SYN_REG_CNT                 6
+#define DRP_SYN_REG_CNT                 8
+
+#define LLCC_LB_CNT_MASK                GENMASK(31, 28)
+#define LLCC_LB_CNT_SHIFT               28
+
+/* Mask and shift macros */
+#define ECC_DB_ERR_COUNT_MASK           GENMASK(4, 0)
+#define ECC_DB_ERR_WAYS_MASK            GENMASK(31, 16)
+#define ECC_DB_ERR_WAYS_SHIFT           BIT(4)
+
+#define ECC_SB_ERR_COUNT_MASK           GENMASK(23, 16)
+#define ECC_SB_ERR_COUNT_SHIFT          BIT(4)
+#define ECC_SB_ERR_WAYS_MASK            GENMASK(15, 0)
+
+#define SB_ECC_ERROR                    BIT(0)
+#define DB_ECC_ERROR                    BIT(1)
+
+#define DRP_TRP_INT_CLEAR               GENMASK(1, 0)
+#define DRP_TRP_CNT_CLEAR               GENMASK(1, 0)
+
+#define SB_ERROR_THRESHOLD              0x1
+#define SB_ERROR_THRESHOLD_SHIFT        24
+#define SB_DB_TRP_INTERRUPT_ENABLE      0x3
+#define TRP0_INTERRUPT_ENABLE           0x1
+#define DRP0_INTERRUPT_ENABLE           BIT(6)
+#define SB_DB_DRP_INTERRUPT_ENABLE      0x3
+
+#define ECC_POLL_MSEC			5000
+
+enum {
+	LLCC_DRAM_CE = 0,
+	LLCC_DRAM_UE,
+	LLCC_TRAM_CE,
+	LLCC_TRAM_UE,
+};
+
+static const struct llcc_edac_reg_data edac_reg_data[] = {
+	[LLCC_DRAM_CE] = {
+		.name = "DRAM Single-bit",
+		.reg_cnt = DRP_SYN_REG_CNT,
+		.count_mask = ECC_SB_ERR_COUNT_MASK,
+		.ways_mask = ECC_SB_ERR_WAYS_MASK,
+		.count_shift = ECC_SB_ERR_COUNT_SHIFT,
+	},
+	[LLCC_DRAM_UE] = {
+		.name = "DRAM Double-bit",
+		.reg_cnt = DRP_SYN_REG_CNT,
+		.count_mask = ECC_DB_ERR_COUNT_MASK,
+		.ways_mask = ECC_DB_ERR_WAYS_MASK,
+		.ways_shift = ECC_DB_ERR_WAYS_SHIFT,
+	},
+	[LLCC_TRAM_CE] = {
+		.name = "TRAM Single-bit",
+		.reg_cnt = TRP_SYN_REG_CNT,
+		.count_mask = ECC_SB_ERR_COUNT_MASK,
+		.ways_mask = ECC_SB_ERR_WAYS_MASK,
+		.count_shift = ECC_SB_ERR_COUNT_SHIFT,
+	},
+	[LLCC_TRAM_UE] = {
+		.name = "TRAM Double-bit",
+		.reg_cnt = TRP_SYN_REG_CNT,
+		.count_mask = ECC_DB_ERR_COUNT_MASK,
+		.ways_mask = ECC_DB_ERR_WAYS_MASK,
+		.ways_shift = ECC_DB_ERR_WAYS_SHIFT,
+	},
+};
+
+static int qcom_llcc_core_setup(struct llcc_drv_data *drv, struct regmap *llcc_bcast_regmap)
+{
+	u32 sb_err_threshold;
+	int ret;
+
+	/*
+	 * Configure interrupt enable registers such that Tag, Data RAM related
+	 * interrupts are propagated to interrupt controller for servicing
+	 */
+	ret = regmap_update_bits(llcc_bcast_regmap, drv->edac_reg_offset->cmn_interrupt_0_enable,
+				 TRP0_INTERRUPT_ENABLE,
+				 TRP0_INTERRUPT_ENABLE);
+	if (ret)
+		return ret;
+
+	ret = regmap_update_bits(llcc_bcast_regmap, drv->edac_reg_offset->trp_interrupt_0_enable,
+				 SB_DB_TRP_INTERRUPT_ENABLE,
+				 SB_DB_TRP_INTERRUPT_ENABLE);
+	if (ret)
+		return ret;
+
+	sb_err_threshold = (SB_ERROR_THRESHOLD << SB_ERROR_THRESHOLD_SHIFT);
+	ret = regmap_write(llcc_bcast_regmap, drv->edac_reg_offset->drp_ecc_error_cfg,
+			   sb_err_threshold);
+	if (ret)
+		return ret;
+
+	ret = regmap_update_bits(llcc_bcast_regmap, drv->edac_reg_offset->cmn_interrupt_0_enable,
+				 DRP0_INTERRUPT_ENABLE,
+				 DRP0_INTERRUPT_ENABLE);
+	if (ret)
+		return ret;
+
+	ret = regmap_write(llcc_bcast_regmap, drv->edac_reg_offset->drp_interrupt_enable,
+			   SB_DB_DRP_INTERRUPT_ENABLE);
+	return ret;
+}
+
+/* Clear the error interrupt and counter registers */
+static int
+qcom_llcc_clear_error_status(int err_type, struct llcc_drv_data *drv)
+{
+	int ret;
+
+	switch (err_type) {
+	case LLCC_DRAM_CE:
+	case LLCC_DRAM_UE:
+		ret = regmap_write(drv->bcast_regmap,
+				   drv->edac_reg_offset->drp_interrupt_clear,
+				   DRP_TRP_INT_CLEAR);
+		if (ret)
+			return ret;
+
+		ret = regmap_write(drv->bcast_regmap,
+				   drv->edac_reg_offset->drp_ecc_error_cntr_clear,
+				   DRP_TRP_CNT_CLEAR);
+		if (ret)
+			return ret;
+		break;
+	case LLCC_TRAM_CE:
+	case LLCC_TRAM_UE:
+		ret = regmap_write(drv->bcast_regmap,
+				   drv->edac_reg_offset->trp_interrupt_0_clear,
+				   DRP_TRP_INT_CLEAR);
+		if (ret)
+			return ret;
+
+		ret = regmap_write(drv->bcast_regmap,
+				   drv->edac_reg_offset->trp_ecc_error_cntr_clear,
+				   DRP_TRP_CNT_CLEAR);
+		if (ret)
+			return ret;
+		break;
+	default:
+		ret = -EINVAL;
+		edac_printk(KERN_CRIT, EDAC_LLCC, "Unexpected error type: %d\n",
+			    err_type);
+	}
+	return ret;
+}
+
+struct qcom_llcc_syn_regs {
+	u32 synd_reg;
+	u32 count_status_reg;
+	u32 ways_status_reg;
+};
+
+static void get_reg_offsets(struct llcc_drv_data *drv, int err_type,
+			    struct qcom_llcc_syn_regs *syn_regs)
+{
+	const struct llcc_edac_reg_offset *edac_reg_offset = drv->edac_reg_offset;
+
+	switch (err_type) {
+	case LLCC_DRAM_CE:
+		syn_regs->synd_reg = edac_reg_offset->drp_ecc_sb_err_syn0;
+		syn_regs->count_status_reg = edac_reg_offset->drp_ecc_error_status1;
+		syn_regs->ways_status_reg = edac_reg_offset->drp_ecc_error_status0;
+		break;
+	case LLCC_DRAM_UE:
+		syn_regs->synd_reg = edac_reg_offset->drp_ecc_db_err_syn0;
+		syn_regs->count_status_reg = edac_reg_offset->drp_ecc_error_status1;
+		syn_regs->ways_status_reg = edac_reg_offset->drp_ecc_error_status0;
+		break;
+	case LLCC_TRAM_CE:
+		syn_regs->synd_reg = edac_reg_offset->trp_ecc_sb_err_syn0;
+		syn_regs->count_status_reg = edac_reg_offset->trp_ecc_error_status1;
+		syn_regs->ways_status_reg = edac_reg_offset->trp_ecc_error_status0;
+		break;
+	case LLCC_TRAM_UE:
+		syn_regs->synd_reg = edac_reg_offset->trp_ecc_db_err_syn0;
+		syn_regs->count_status_reg = edac_reg_offset->trp_ecc_error_status1;
+		syn_regs->ways_status_reg = edac_reg_offset->trp_ecc_error_status0;
+		break;
+	}
+}
+
+/* Dump Syndrome registers data for Tag RAM, Data RAM bit errors*/
+static int
+dump_syn_reg_values(struct llcc_drv_data *drv, u32 bank, int err_type)
+{
+	struct llcc_edac_reg_data reg_data = edac_reg_data[err_type];
+	struct qcom_llcc_syn_regs regs = { };
+	int err_cnt, err_ways, ret, i;
+	u32 synd_reg, synd_val;
+
+	get_reg_offsets(drv, err_type, &regs);
+
+	for (i = 0; i < reg_data.reg_cnt; i++) {
+		synd_reg = regs.synd_reg + (i * 4);
+		ret = regmap_read(drv->regmaps[bank], synd_reg,
+				  &synd_val);
+		if (ret)
+			goto clear;
+
+		edac_printk(KERN_CRIT, EDAC_LLCC, "%s: ECC_SYN%d: 0x%8x\n",
+			    reg_data.name, i, synd_val);
+	}
+
+	ret = regmap_read(drv->regmaps[bank], regs.count_status_reg,
+			  &err_cnt);
+	if (ret)
+		goto clear;
+
+	err_cnt &= reg_data.count_mask;
+	err_cnt >>= reg_data.count_shift;
+	edac_printk(KERN_CRIT, EDAC_LLCC, "%s: Error count: 0x%4x\n",
+		    reg_data.name, err_cnt);
+
+	ret = regmap_read(drv->regmaps[bank], regs.ways_status_reg,
+			  &err_ways);
+	if (ret)
+		goto clear;
+
+	err_ways &= reg_data.ways_mask;
+	err_ways >>= reg_data.ways_shift;
+
+	edac_printk(KERN_CRIT, EDAC_LLCC, "%s: Error ways: 0x%4x\n",
+		    reg_data.name, err_ways);
+
+clear:
+	return qcom_llcc_clear_error_status(err_type, drv);
+}
+
+static int
+dump_syn_reg(struct edac_device_ctl_info *edev_ctl, int err_type, u32 bank)
+{
+	struct llcc_drv_data *drv = edev_ctl->dev->platform_data;
+	int ret;
+
+	ret = dump_syn_reg_values(drv, bank, err_type);
+	if (ret)
+		return ret;
+
+	switch (err_type) {
+	case LLCC_DRAM_CE:
+		edac_device_handle_ce(edev_ctl, 0, bank,
+				      "LLCC Data RAM correctable Error");
+		break;
+	case LLCC_DRAM_UE:
+		edac_device_handle_ue(edev_ctl, 0, bank,
+				      "LLCC Data RAM uncorrectable Error");
+		break;
+	case LLCC_TRAM_CE:
+		edac_device_handle_ce(edev_ctl, 0, bank,
+				      "LLCC Tag RAM correctable Error");
+		break;
+	case LLCC_TRAM_UE:
+		edac_device_handle_ue(edev_ctl, 0, bank,
+				      "LLCC Tag RAM uncorrectable Error");
+		break;
+	default:
+		ret = -EINVAL;
+		edac_printk(KERN_CRIT, EDAC_LLCC, "Unexpected error type: %d\n",
+			    err_type);
+	}
+
+	return ret;
+}
+
+static irqreturn_t llcc_ecc_irq_handler(int irq, void *edev_ctl)
+{
+	struct edac_device_ctl_info *edac_dev_ctl = edev_ctl;
+	struct llcc_drv_data *drv = edac_dev_ctl->dev->platform_data;
+	irqreturn_t irq_rc = IRQ_NONE;
+	u32 drp_error, trp_error, i;
+	int ret;
+
+	/* Iterate over the banks and look for Tag RAM or Data RAM errors */
+	for (i = 0; i < drv->num_banks; i++) {
+		ret = regmap_read(drv->regmaps[i], drv->edac_reg_offset->drp_interrupt_status,
+				  &drp_error);
+
+		if (!ret && (drp_error & SB_ECC_ERROR)) {
+			edac_printk(KERN_CRIT, EDAC_LLCC,
+				    "Single Bit Error detected in Data RAM\n");
+			ret = dump_syn_reg(edev_ctl, LLCC_DRAM_CE, i);
+		} else if (!ret && (drp_error & DB_ECC_ERROR)) {
+			edac_printk(KERN_CRIT, EDAC_LLCC,
+				    "Double Bit Error detected in Data RAM\n");
+			ret = dump_syn_reg(edev_ctl, LLCC_DRAM_UE, i);
+		}
+		if (!ret)
+			irq_rc = IRQ_HANDLED;
+
+		ret = regmap_read(drv->regmaps[i], drv->edac_reg_offset->trp_interrupt_0_status,
+				  &trp_error);
+
+		if (!ret && (trp_error & SB_ECC_ERROR)) {
+			edac_printk(KERN_CRIT, EDAC_LLCC,
+				    "Single Bit Error detected in Tag RAM\n");
+			ret = dump_syn_reg(edev_ctl, LLCC_TRAM_CE, i);
+		} else if (!ret && (trp_error & DB_ECC_ERROR)) {
+			edac_printk(KERN_CRIT, EDAC_LLCC,
+				    "Double Bit Error detected in Tag RAM\n");
+			ret = dump_syn_reg(edev_ctl, LLCC_TRAM_UE, i);
+		}
+		if (!ret)
+			irq_rc = IRQ_HANDLED;
+	}
+
+	return irq_rc;
+}
+
+static void llcc_ecc_check(struct edac_device_ctl_info *edev_ctl)
+{
+	llcc_ecc_irq_handler(0, edev_ctl);
+}
+
+static int qcom_llcc_edac_probe(struct platform_device *pdev)
+{
+	struct llcc_drv_data *llcc_driv_data = pdev->dev.platform_data;
+	struct edac_device_ctl_info *edev_ctl;
+	struct device *dev = &pdev->dev;
+	int ecc_irq;
+	int rc;
+
+	if (!llcc_driv_data->ecc_irq_configured) {
+		rc = qcom_llcc_core_setup(llcc_driv_data, llcc_driv_data->bcast_regmap);
+		if (rc)
+			return rc;
+	}
+
+	/* Allocate edac control info */
+	edev_ctl = edac_device_alloc_ctl_info(0, "qcom-llcc", 1, "bank",
+					      llcc_driv_data->num_banks, 1,
+					      edac_device_alloc_index());
+
+	if (!edev_ctl)
+		return -ENOMEM;
+
+	edev_ctl->dev = dev;
+	edev_ctl->mod_name = dev_name(dev);
+	edev_ctl->dev_name = dev_name(dev);
+	edev_ctl->ctl_name = "llcc";
+	edev_ctl->panic_on_ue = LLCC_ERP_PANIC_ON_UE;
+
+	/* Check if LLCC driver has passed ECC IRQ */
+	ecc_irq = llcc_driv_data->ecc_irq;
+	if (ecc_irq > 0) {
+		/* Use interrupt mode if IRQ is available */
+		rc = devm_request_irq(dev, ecc_irq, llcc_ecc_irq_handler,
+			      IRQF_TRIGGER_HIGH, "llcc_ecc", edev_ctl);
+		if (!rc) {
+			edac_op_state = EDAC_OPSTATE_INT;
+			goto irq_done;
+		}
+	}
+
+	/* Fall back to polling mode otherwise */
+	edev_ctl->poll_msec = ECC_POLL_MSEC;
+	edev_ctl->edac_check = llcc_ecc_check;
+	edac_op_state = EDAC_OPSTATE_POLL;
+
+irq_done:
+	rc = edac_device_add_device(edev_ctl);
+	if (rc) {
+		edac_device_free_ctl_info(edev_ctl);
+		return rc;
+	}
+
+	platform_set_drvdata(pdev, edev_ctl);
+
+	return rc;
+}
+
+static void qcom_llcc_edac_remove(struct platform_device *pdev)
+{
+	struct edac_device_ctl_info *edev_ctl = dev_get_drvdata(&pdev->dev);
+
+	edac_device_del_device(edev_ctl->dev);
+	edac_device_free_ctl_info(edev_ctl);
+}
+
+static const struct platform_device_id qcom_llcc_edac_id_table[] = {
+	{ .name = "qcom_llcc_edac" },
+	{}
+};
+MODULE_DEVICE_TABLE(platform, qcom_llcc_edac_id_table);
+
+static struct platform_driver qcom_llcc_edac_driver = {
+	.probe = qcom_llcc_edac_probe,
+	.remove = qcom_llcc_edac_remove,
+	.driver = {
+		.name = "qcom_llcc_edac",
+	},
+	.id_table = qcom_llcc_edac_id_table,
+};
+module_platform_driver(qcom_llcc_edac_driver);
+
+MODULE_DESCRIPTION("QCOM EDAC driver");
+MODULE_LICENSE("GPL v2");