From a5f7a5bb3b7f28ba7e4fa246775b29a0e5537255 Mon Sep 17 00:00:00 2001 From: Jinke Han Date: Tue, 8 Sep 2026 15:37:42 +0800 Subject: x86/kprobes: Fix crash when probing CS CALL instructions When using eBPF to probe CS CALL instructions within a function, a crash can be triggered. The eBPF tool probes offset 257 of the __hrtimer_run_queues() function: <__hrtimer_run_queues+249>: nopl 0x0(%rax,%rax,1) <__hrtimer_run_queues+254>: mov %r14,%rdi <__hrtimer_run_queues+257>: cs call <__x86_indirect_thunk_r12> <__hrtimer_run_queues+263>: mov %eax,%r12d <__hrtimer_run_queues+266>: xchg %ax,%ax <__hrtimer_run_queues+268>: mov %r13,%rdi Which triggers this crash: BUG: unable to handle page fault for address: 00000000000f41c9 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page PGD 0 P4D 0 Oops: 0002 [#1] SMP NOPTI CPU: 1 PID: 0 Comm: swapper/1 Kdump: loaded Tainted: P RIP: 0010:__hrtimer_run_queues+0x106/0x230 Note that __hrtimer_run_queues+0x106 is __hrtimer_run_queues+262, which is at the 6th byte of the above CS CALL instruction. Since the CS CALL instruction occupies 6 bytes, the exception occurred in the middle of that call instruction. The root cause is that when using eBPF tools to probe in the middle of a function, a kprobe with INT3 is used as the underlying implementation. During single-step emulation of the original CALL instruction, int3_emulate_call() assumes that the probed CALL instruction is 5 bytes long. However, the actual CS-prefixed CALL instruction occupies 6 bytes, so it constructs an incorrect exception return address. When the CPU returns from the kprobe handler, the next instruction to be executed is at the address of the last byte of that CS CALL instruction. Coincidentally, starting from that address, the CPU fetches and decodes a completely different instruction, which ultimately triggers a kernel crash. Fix the issue by using the actual instruction length obtained from the instruction decoder when constructing the exception return address, rather than relying on the hardcoded CALL_INSN_SIZE macro. [ mingo: Refined the changelog ] Fixes: 6256e668b7af ("x86/kprobes: Use int3 instead of debug trap for single-step") Suggested-by: Masami Hiramatsu (Google) Signed-off-by: Jinke Han Signed-off-by: Ingo Molnar Reviewed-by: Masami Hiramatsu (Google) Acked-by: Yafang Shao Acked-by: Borislav Petkov Cc: Peter Zijlstra Link: https://patch.msgid.link/20260908073742.GA10517@didi-ThinkCentre-M920t-N000 --- drivers/scsi/a3000.c | 315 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 315 insertions(+) create mode 100644 drivers/scsi/a3000.c (limited to 'drivers/scsi/a3000.c') diff --git a/drivers/scsi/a3000.c b/drivers/scsi/a3000.c new file mode 100644 index 000000000..bf054dd76 --- /dev/null +++ b/drivers/scsi/a3000.c @@ -0,0 +1,315 @@ +// SPDX-License-Identifier: GPL-2.0-only +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include +#include + +#include +#include +#include +#include +#include +#include "wd33c93.h" +#include "a3000.h" + + +struct a3000_hostdata { + struct WD33C93_hostdata wh; + struct a3000_scsiregs *regs; + struct device *dev; +}; + +#define DMA_DIR(d) ((d == DATA_OUT_DIR) ? DMA_TO_DEVICE : DMA_FROM_DEVICE) + +static irqreturn_t a3000_intr(int irq, void *data) +{ + struct Scsi_Host *instance = data; + struct a3000_hostdata *hdata = shost_priv(instance); + unsigned int status = hdata->regs->ISTR; + unsigned long flags; + + if (!(status & ISTR_INT_P)) + return IRQ_NONE; + if (status & ISTR_INTS) { + spin_lock_irqsave(instance->host_lock, flags); + wd33c93_intr(instance); + spin_unlock_irqrestore(instance->host_lock, flags); + return IRQ_HANDLED; + } + pr_warn("Non-serviced A3000 SCSI-interrupt? ISTR = %02x\n", status); + return IRQ_NONE; +} + +static int dma_setup(struct scsi_cmnd *cmd, int dir_in) +{ + struct scsi_pointer *scsi_pointer = WD33C93_scsi_pointer(cmd); + unsigned long len = scsi_pointer->this_residual; + struct Scsi_Host *instance = cmd->device->host; + struct a3000_hostdata *hdata = shost_priv(instance); + struct WD33C93_hostdata *wh = &hdata->wh; + struct a3000_scsiregs *regs = hdata->regs; + unsigned short cntr = CNTR_PDMD | CNTR_INTEN; + dma_addr_t addr; + + addr = dma_map_single(hdata->dev, scsi_pointer->ptr, + len, DMA_DIR(dir_in)); + if (dma_mapping_error(hdata->dev, addr)) { + dev_warn(hdata->dev, "cannot map SCSI data block %p\n", + scsi_pointer->ptr); + return 1; + } + scsi_pointer->dma_handle = addr; + + /* + * if the physical address has the wrong alignment, or if + * physical address is bad, or if it is a write and at the + * end of a physical memory chunk, then allocate a bounce + * buffer + * MSch 20220629 - only wrong alignment tested - bounce + * buffer returned by kmalloc is guaranteed to be aligned + */ + if (addr & A3000_XFER_MASK) { + WARN_ONCE(1, "Invalid alignment for DMA!"); + /* drop useless mapping */ + dma_unmap_single(hdata->dev, scsi_pointer->dma_handle, + scsi_pointer->this_residual, + DMA_DIR(dir_in)); + + wh->dma_bounce_len = (scsi_pointer->this_residual + 511) & ~0x1ff; + wh->dma_bounce_buffer = kmalloc(wh->dma_bounce_len, + GFP_KERNEL); + + /* can't allocate memory; use PIO */ + if (!wh->dma_bounce_buffer) { + wh->dma_bounce_len = 0; + scsi_pointer->dma_handle = (dma_addr_t) NULL; + return 1; + } + + if (!dir_in) { + /* copy to bounce buffer for a write */ + memcpy(wh->dma_bounce_buffer, scsi_pointer->ptr, + scsi_pointer->this_residual); + } + + addr = dma_map_single(hdata->dev, scsi_pointer->ptr, + len, DMA_DIR(dir_in)); + if (dma_mapping_error(hdata->dev, addr)) { + dev_warn(hdata->dev, + "cannot map SCSI data block %p\n", + scsi_pointer->ptr); + return 1; + } + scsi_pointer->dma_handle = addr; + } + + /* setup dma direction */ + if (!dir_in) + cntr |= CNTR_DDIR; + + /* remember direction */ + wh->dma_dir = dir_in; + + regs->CNTR = cntr; + + /* setup DMA *physical* address */ + regs->ACR = addr; + + /* no more cache flush here - dma_map_single() takes care */ + + /* start DMA */ + mb(); /* make sure setup is completed */ + regs->ST_DMA = 1; + mb(); /* make sure DMA has started before next IO */ + + /* return success */ + return 0; +} + +static void dma_stop(struct Scsi_Host *instance, struct scsi_cmnd *SCpnt, + int status) +{ + struct scsi_pointer *scsi_pointer = WD33C93_scsi_pointer(SCpnt); + struct a3000_hostdata *hdata = shost_priv(instance); + struct WD33C93_hostdata *wh = &hdata->wh; + struct a3000_scsiregs *regs = hdata->regs; + + /* disable SCSI interrupts */ + unsigned short cntr = CNTR_PDMD; + + if (!wh->dma_dir) + cntr |= CNTR_DDIR; + + regs->CNTR = cntr; + mb(); /* make sure CNTR is updated before next IO */ + + /* flush if we were reading */ + if (wh->dma_dir) { + regs->FLUSH = 1; + mb(); /* don't allow prefetch */ + while (!(regs->ISTR & ISTR_FE_FLG)) + barrier(); + mb(); /* no IO until FLUSH is done */ + } + + /* clear a possible interrupt */ + /* I think that this CINT is only necessary if you are + * using the terminal count features. HM 7 Mar 1994 + */ + regs->CINT = 1; + + /* stop DMA */ + regs->SP_DMA = 1; + mb(); /* make sure DMA is stopped before next IO */ + + /* restore the CONTROL bits (minus the direction flag) */ + regs->CNTR = CNTR_PDMD | CNTR_INTEN; + mb(); /* make sure CNTR is updated before next IO */ + + dma_unmap_single(hdata->dev, scsi_pointer->dma_handle, + scsi_pointer->this_residual, + DMA_DIR(wh->dma_dir)); + + /* copy from a bounce buffer, if necessary */ + if (status && wh->dma_bounce_buffer) { + if (SCpnt) { + if (wh->dma_dir && SCpnt) + memcpy(scsi_pointer->ptr, wh->dma_bounce_buffer, + scsi_pointer->this_residual); + kfree(wh->dma_bounce_buffer); + wh->dma_bounce_buffer = NULL; + wh->dma_bounce_len = 0; + } else { + kfree(wh->dma_bounce_buffer); + wh->dma_bounce_buffer = NULL; + wh->dma_bounce_len = 0; + } + } +} + +static const struct scsi_host_template amiga_a3000_scsi_template = { + .module = THIS_MODULE, + .name = "Amiga 3000 built-in SCSI", + .show_info = wd33c93_show_info, + .write_info = wd33c93_write_info, + .proc_name = "A3000", + .queuecommand = wd33c93_queuecommand, + .eh_abort_handler = wd33c93_abort, + .eh_host_reset_handler = wd33c93_host_reset, + .can_queue = CAN_QUEUE, + .this_id = 7, + .sg_tablesize = SG_ALL, + .cmd_per_lun = CMD_PER_LUN, + .cmd_size = sizeof(struct scsi_pointer), +}; + +static int __init amiga_a3000_scsi_probe(struct platform_device *pdev) +{ + struct resource *res; + struct Scsi_Host *instance; + int error; + struct a3000_scsiregs *regs; + wd33c93_regs wdregs; + struct a3000_hostdata *hdata; + + if (dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32))) { + dev_warn(&pdev->dev, "cannot use 32 bit DMA\n"); + return -ENODEV; + } + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + if (!res) + return -ENODEV; + + if (!request_mem_region(res->start, resource_size(res), "wd33c93")) + return -EBUSY; + + instance = scsi_host_alloc(&amiga_a3000_scsi_template, + sizeof(struct a3000_hostdata)); + if (!instance) { + error = -ENOMEM; + goto fail_alloc; + } + + instance->irq = IRQ_AMIGA_PORTS; + + regs = ZTWO_VADDR(res->start); + regs->DAWR = DAWR_A3000; + + wdregs.SASR = ®s->SASR; + wdregs.SCMD = ®s->SCMD; + + hdata = shost_priv(instance); + hdata->dev = &pdev->dev; + hdata->wh.no_sync = 0xff; + hdata->wh.fast = 0; + hdata->wh.dma_mode = CTRL_DMA; + hdata->regs = regs; + + wd33c93_init(instance, wdregs, dma_setup, dma_stop, WD33C93_FS_12_15); + error = request_irq(IRQ_AMIGA_PORTS, a3000_intr, IRQF_SHARED, + "A3000 SCSI", instance); + if (error) + goto fail_irq; + + regs->CNTR = CNTR_PDMD | CNTR_INTEN; + + error = scsi_add_host(instance, NULL); + if (error) + goto fail_host; + + platform_set_drvdata(pdev, instance); + + scsi_scan_host(instance); + return 0; + +fail_host: + free_irq(IRQ_AMIGA_PORTS, instance); +fail_irq: + scsi_host_put(instance); +fail_alloc: + release_mem_region(res->start, resource_size(res)); + return error; +} + +static void __exit amiga_a3000_scsi_remove(struct platform_device *pdev) +{ + struct Scsi_Host *instance = platform_get_drvdata(pdev); + struct a3000_hostdata *hdata = shost_priv(instance); + struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + + hdata->regs->CNTR = 0; + scsi_remove_host(instance); + free_irq(IRQ_AMIGA_PORTS, instance); + scsi_host_put(instance); + release_mem_region(res->start, resource_size(res)); +} + +/* + * amiga_a3000_scsi_remove() lives in .exit.text. For drivers registered via + * module_platform_driver_probe() this is ok because they cannot get unbound at + * runtime. So mark the driver struct with __refdata to prevent modpost + * triggering a section mismatch warning. + */ +static struct platform_driver amiga_a3000_scsi_driver __refdata = { + .remove = __exit_p(amiga_a3000_scsi_remove), + .driver = { + .name = "amiga-a3000-scsi", + }, +}; + +module_platform_driver_probe(amiga_a3000_scsi_driver, amiga_a3000_scsi_probe); + +MODULE_DESCRIPTION("Amiga 3000 built-in SCSI"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("platform:amiga-a3000-scsi"); -- cgit v1.3.1