x86/kprobes: Fix crash when probing CS CALL instructionsgrafted

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) <mhiramat@kernel.org>
Signed-off-by: Jinke Han <jinkehan@didiglobal.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://patch.msgid.link/20260908073742.GA10517@didi-ThinkCentre-M920t-N000

1 files changed, 201 insertions, 0 deletions

diff --git a/drivers/bcma/driver_pcie2.c b/drivers/bcma/driver_pcie2.c
new file mode 100644
index 000000000..cf889fc62
--- /dev/null
+++ b/drivers/bcma/driver_pcie2.c
@@ -0,0 +1,201 @@
+/*
+ * Broadcom specific AMBA
+ * PCIe Gen 2 Core
+ *
+ * Copyright 2014, Broadcom Corporation
+ * Copyright 2014, Rafał Miłecki <zajec5@gmail.com>
+ *
+ * Licensed under the GNU/GPL. See COPYING for details.
+ */
+
+#include "bcma_private.h"
+#include <linux/bcma/bcma.h>
+#include <linux/pci.h>
+
+/**************************************************
+ * R/W ops.
+ **************************************************/
+
+#if 0
+static u32 bcma_core_pcie2_cfg_read(struct bcma_drv_pcie2 *pcie2, u32 addr)
+{
+	pcie2_write32(pcie2, BCMA_CORE_PCIE2_CONFIGINDADDR, addr);
+	pcie2_read32(pcie2, BCMA_CORE_PCIE2_CONFIGINDADDR);
+	return pcie2_read32(pcie2, BCMA_CORE_PCIE2_CONFIGINDDATA);
+}
+#endif
+
+static void bcma_core_pcie2_cfg_write(struct bcma_drv_pcie2 *pcie2, u32 addr,
+				      u32 val)
+{
+	pcie2_write32(pcie2, BCMA_CORE_PCIE2_CONFIGINDADDR, addr);
+	pcie2_write32(pcie2, BCMA_CORE_PCIE2_CONFIGINDDATA, val);
+}
+
+/**************************************************
+ * Init.
+ **************************************************/
+
+static u32 bcma_core_pcie2_war_delay_perst_enab(struct bcma_drv_pcie2 *pcie2,
+						bool enable)
+{
+	u32 val;
+
+	/* restore back to default */
+	val = pcie2_read32(pcie2, BCMA_CORE_PCIE2_CLK_CONTROL);
+	val |= PCIE2_CLKC_DLYPERST;
+	val &= ~PCIE2_CLKC_DISSPROMLD;
+	if (enable) {
+		val &= ~PCIE2_CLKC_DLYPERST;
+		val |= PCIE2_CLKC_DISSPROMLD;
+	}
+	pcie2_write32(pcie2, (BCMA_CORE_PCIE2_CLK_CONTROL), val);
+	/* flush */
+	return pcie2_read32(pcie2, BCMA_CORE_PCIE2_CLK_CONTROL);
+}
+
+static void bcma_core_pcie2_set_ltr_vals(struct bcma_drv_pcie2 *pcie2)
+{
+	/* LTR0 */
+	pcie2_write32(pcie2, BCMA_CORE_PCIE2_CONFIGINDADDR, 0x844);
+	pcie2_write32(pcie2, BCMA_CORE_PCIE2_CONFIGINDDATA, 0x883c883c);
+	/* LTR1 */
+	pcie2_write32(pcie2, BCMA_CORE_PCIE2_CONFIGINDADDR, 0x848);
+	pcie2_write32(pcie2, BCMA_CORE_PCIE2_CONFIGINDDATA, 0x88648864);
+	/* LTR2 */
+	pcie2_write32(pcie2, BCMA_CORE_PCIE2_CONFIGINDADDR, 0x84C);
+	pcie2_write32(pcie2, BCMA_CORE_PCIE2_CONFIGINDDATA, 0x90039003);
+}
+
+static void bcma_core_pcie2_hw_ltr_war(struct bcma_drv_pcie2 *pcie2)
+{
+	u8 core_rev = pcie2->core->id.rev;
+	u32 devstsctr2;
+
+	if (core_rev < 2 || core_rev == 10 || core_rev > 13)
+		return;
+
+	pcie2_write32(pcie2, BCMA_CORE_PCIE2_CONFIGINDADDR,
+		      PCIE2_CAP_DEVSTSCTRL2_OFFSET);
+	devstsctr2 = pcie2_read32(pcie2, BCMA_CORE_PCIE2_CONFIGINDDATA);
+	if (devstsctr2 & PCIE2_CAP_DEVSTSCTRL2_LTRENAB) {
+		/* force the right LTR values */
+		bcma_core_pcie2_set_ltr_vals(pcie2);
+
+		/* TODO:
+		 *si_core_wrapperreg(pcie2, 3, 0x60, 0x8080, 0);
+		 */
+
+		/* enable the LTR */
+		devstsctr2 |= PCIE2_CAP_DEVSTSCTRL2_LTRENAB;
+		pcie2_write32(pcie2, BCMA_CORE_PCIE2_CONFIGINDADDR,
+			      PCIE2_CAP_DEVSTSCTRL2_OFFSET);
+		pcie2_write32(pcie2, BCMA_CORE_PCIE2_CONFIGINDDATA, devstsctr2);
+
+		/* set the LTR state to be active */
+		pcie2_write32(pcie2, BCMA_CORE_PCIE2_LTR_STATE,
+			      PCIE2_LTR_ACTIVE);
+		usleep_range(1000, 2000);
+
+		/* set the LTR state to be sleep */
+		pcie2_write32(pcie2, BCMA_CORE_PCIE2_LTR_STATE,
+			      PCIE2_LTR_SLEEP);
+		usleep_range(1000, 2000);
+	}
+}
+
+static void pciedev_crwlpciegen2(struct bcma_drv_pcie2 *pcie2)
+{
+	u8 core_rev = pcie2->core->id.rev;
+	bool pciewar160, pciewar162;
+
+	pciewar160 = core_rev == 7 || core_rev == 9 || core_rev == 11;
+	pciewar162 = core_rev == 5 || core_rev == 7 || core_rev == 8 ||
+		     core_rev == 9 || core_rev == 11;
+
+	if (!pciewar160 && !pciewar162)
+		return;
+
+/* TODO */
+#if 0
+	pcie2_set32(pcie2, BCMA_CORE_PCIE2_CLK_CONTROL,
+		    PCIE_DISABLE_L1CLK_GATING);
+#if 0
+	pcie2_write32(pcie2, BCMA_CORE_PCIE2_CONFIGINDADDR,
+		      PCIEGEN2_COE_PVT_TL_CTRL_0);
+	pcie2_mask32(pcie2, BCMA_CORE_PCIE2_CONFIGINDDATA,
+		     ~(1 << COE_PVT_TL_CTRL_0_PM_DIS_L1_REENTRY_BIT));
+#endif
+#endif
+}
+
+static void pciedev_crwlpciegen2_180(struct bcma_drv_pcie2 *pcie2)
+{
+	pcie2_write32(pcie2, BCMA_CORE_PCIE2_CONFIGINDADDR, PCIE2_PMCR_REFUP);
+	pcie2_set32(pcie2, BCMA_CORE_PCIE2_CONFIGINDDATA, 0x1f);
+}
+
+static void pciedev_crwlpciegen2_182(struct bcma_drv_pcie2 *pcie2)
+{
+	pcie2_write32(pcie2, BCMA_CORE_PCIE2_CONFIGINDADDR, PCIE2_SBMBX);
+	pcie2_write32(pcie2, BCMA_CORE_PCIE2_CONFIGINDDATA, 1 << 0);
+}
+
+static void pciedev_reg_pm_clk_period(struct bcma_drv_pcie2 *pcie2)
+{
+	struct bcma_drv_cc *drv_cc = &pcie2->core->bus->drv_cc;
+	u8 core_rev = pcie2->core->id.rev;
+	u32 alp_khz, pm_value;
+
+	if (core_rev <= 13) {
+		alp_khz = bcma_pmu_get_alp_clock(drv_cc) / 1000;
+		pm_value = (1000000 * 2) / alp_khz;
+		pcie2_write32(pcie2, BCMA_CORE_PCIE2_CONFIGINDADDR,
+			      PCIE2_PVT_REG_PM_CLK_PERIOD);
+		pcie2_write32(pcie2, BCMA_CORE_PCIE2_CONFIGINDDATA, pm_value);
+	}
+}
+
+void bcma_core_pcie2_init(struct bcma_drv_pcie2 *pcie2)
+{
+	struct bcma_bus *bus = pcie2->core->bus;
+	struct bcma_chipinfo *ci = &bus->chipinfo;
+	u32 tmp;
+
+	tmp = pcie2_read32(pcie2, BCMA_CORE_PCIE2_SPROM(54));
+	if ((tmp & 0xe) >> 1 == 2)
+		bcma_core_pcie2_cfg_write(pcie2, 0x4e0, 0x17);
+
+	switch (bus->chipinfo.id) {
+	case BCMA_CHIP_ID_BCM4360:
+	case BCMA_CHIP_ID_BCM4352:
+		pcie2->reqsize = 1024;
+		break;
+	default:
+		pcie2->reqsize = 128;
+		break;
+	}
+
+	if (ci->id == BCMA_CHIP_ID_BCM4360 && ci->rev > 3)
+		bcma_core_pcie2_war_delay_perst_enab(pcie2, true);
+	bcma_core_pcie2_hw_ltr_war(pcie2);
+	pciedev_crwlpciegen2(pcie2);
+	pciedev_reg_pm_clk_period(pcie2);
+	pciedev_crwlpciegen2_180(pcie2);
+	pciedev_crwlpciegen2_182(pcie2);
+}
+
+/**************************************************
+ * Runtime ops.
+ **************************************************/
+
+void bcma_core_pcie2_up(struct bcma_drv_pcie2 *pcie2)
+{
+	struct bcma_bus *bus = pcie2->core->bus;
+	struct pci_dev *dev = bus->host_pci;
+	int err;
+
+	err = pcie_set_readrq(dev, pcie2->reqsize);
+	if (err)
+		bcma_err(bus, "Error setting PCI_EXP_DEVCTL_READRQ: %d\n", err);
+}