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/video/fbdev/sh7760fb.c | 584 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 584 insertions(+) create mode 100644 drivers/video/fbdev/sh7760fb.c (limited to 'drivers/video/fbdev/sh7760fb.c') diff --git a/drivers/video/fbdev/sh7760fb.c b/drivers/video/fbdev/sh7760fb.c new file mode 100644 index 000000000..130adef2e --- /dev/null +++ b/drivers/video/fbdev/sh7760fb.c @@ -0,0 +1,584 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * SH7760/SH7763 LCDC Framebuffer driver. + * + * (c) 2006-2008 MSC Vertriebsges.m.b.H., + * Manuel Lauss + * (c) 2008 Nobuhiro Iwamatsu + * + * PLEASE HAVE A LOOK AT Documentation/fb/sh7760fb.rst! + * + * Thanks to Siegfried Schaefer + * for his original source and testing! + * + * sh7760_setcolreg get from drivers/video/sh_mobile_lcdcfb.c + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include + +struct sh7760fb_par { + void __iomem *base; + int irq; + + struct sh7760fb_platdata *pd; /* display information */ + + dma_addr_t fbdma; /* physical address */ + + int rot; /* rotation enabled? */ + + u32 pseudo_palette[16]; + + struct platform_device *dev; + struct resource *ioarea; + struct completion vsync; /* vsync irq event */ +}; + +static irqreturn_t sh7760fb_irq(int irq, void *data) +{ + struct completion *c = data; + + complete(c); + + return IRQ_HANDLED; +} + +/* wait_for_lps - wait until power supply has reached a certain state. */ +static int wait_for_lps(struct sh7760fb_par *par, int val) +{ + int i = 100; + while (--i && ((ioread16(par->base + LDPMMR) & 3) != val)) + msleep(1); + + if (i <= 0) + return -ETIMEDOUT; + + return 0; +} + +/* en/disable the LCDC */ +static int sh7760fb_blank(int blank, struct fb_info *info) +{ + struct sh7760fb_par *par = info->par; + struct sh7760fb_platdata *pd = par->pd; + unsigned short cntr = ioread16(par->base + LDCNTR); + unsigned short intr = ioread16(par->base + LDINTR); + int lps; + + if (blank == FB_BLANK_UNBLANK) { + intr |= VINT_START; + cntr = LDCNTR_DON2 | LDCNTR_DON; + lps = 3; + } else { + intr &= ~VINT_START; + cntr = LDCNTR_DON2; + lps = 0; + } + + if (pd->blank) + pd->blank(blank); + + iowrite16(intr, par->base + LDINTR); + iowrite16(cntr, par->base + LDCNTR); + + return wait_for_lps(par, lps); +} + +static int sh7760_setcolreg (u_int regno, + u_int red, u_int green, u_int blue, + u_int transp, struct fb_info *info) +{ + u32 *palette = info->pseudo_palette; + + if (regno >= 16) + return -EINVAL; + + /* only FB_VISUAL_TRUECOLOR supported */ + + red >>= 16 - info->var.red.length; + green >>= 16 - info->var.green.length; + blue >>= 16 - info->var.blue.length; + transp >>= 16 - info->var.transp.length; + + palette[regno] = (red << info->var.red.offset) | + (green << info->var.green.offset) | + (blue << info->var.blue.offset) | + (transp << info->var.transp.offset); + + return 0; +} + +static int sh7760fb_get_color_info(struct fb_info *info, + u16 lddfr, int *bpp, int *gray) +{ + int lbpp, lgray; + + lgray = lbpp = 0; + + switch (lddfr & LDDFR_COLOR_MASK) { + case LDDFR_1BPP_MONO: + lgray = 1; + lbpp = 1; + break; + case LDDFR_2BPP_MONO: + lgray = 1; + lbpp = 2; + break; + case LDDFR_4BPP_MONO: + lgray = 1; + fallthrough; + case LDDFR_4BPP: + lbpp = 4; + break; + case LDDFR_6BPP_MONO: + lgray = 1; + fallthrough; + case LDDFR_8BPP: + lbpp = 8; + break; + case LDDFR_16BPP_RGB555: + case LDDFR_16BPP_RGB565: + lbpp = 16; + lgray = 0; + break; + default: + fb_dbg(info, "unsupported LDDFR bit depth.\n"); + return -EINVAL; + } + + if (bpp) + *bpp = lbpp; + if (gray) + *gray = lgray; + + return 0; +} + +static int sh7760fb_check_var(struct fb_var_screeninfo *var, + struct fb_info *info) +{ + struct fb_fix_screeninfo *fix = &info->fix; + struct sh7760fb_par *par = info->par; + int ret, bpp; + + /* get color info from register value */ + ret = sh7760fb_get_color_info(info, par->pd->lddfr, &bpp, NULL); + if (ret) + return ret; + + var->bits_per_pixel = bpp; + + if ((var->grayscale) && (var->bits_per_pixel == 1)) + fix->visual = FB_VISUAL_MONO10; + else if (var->bits_per_pixel >= 15) + fix->visual = FB_VISUAL_TRUECOLOR; + else + fix->visual = FB_VISUAL_PSEUDOCOLOR; + + /* TODO: add some more validation here */ + return 0; +} + +/* + * sh7760fb_set_par - set videomode. + * + * NOTE: The rotation, grayscale and DSTN codepaths are + * totally untested! + */ +static int sh7760fb_set_par(struct fb_info *info) +{ + struct sh7760fb_par *par = info->par; + struct fb_videomode *vm = par->pd->def_mode; + unsigned long sbase, dstn_off, ldsarl, stride; + unsigned short hsynp, hsynw, htcn, hdcn; + unsigned short vsynp, vsynw, vtln, vdln; + unsigned short lddfr, ldmtr; + int ret, bpp, gray; + + par->rot = par->pd->rotate; + + /* rotate only works with xres <= 320 */ + if (par->rot && (vm->xres > 320)) { + fb_dbg(info, "rotation disabled due to display size\n"); + par->rot = 0; + } + + /* calculate LCDC reg vals from display parameters */ + hsynp = vm->right_margin + vm->xres; + hsynw = vm->hsync_len; + htcn = vm->left_margin + hsynp + hsynw; + hdcn = vm->xres; + vsynp = vm->lower_margin + vm->yres; + vsynw = vm->vsync_len; + vtln = vm->upper_margin + vsynp + vsynw; + vdln = vm->yres; + + /* get color info from register value */ + ret = sh7760fb_get_color_info(info, par->pd->lddfr, &bpp, &gray); + if (ret) + return ret; + + fb_dbg(info, "%dx%d %dbpp %s (orientation %s)\n", hdcn, + vdln, bpp, gray ? "grayscale" : "color", + par->rot ? "rotated" : "normal"); + +#ifdef CONFIG_CPU_LITTLE_ENDIAN + lddfr = par->pd->lddfr | (1 << 8); +#else + lddfr = par->pd->lddfr & ~(1 << 8); +#endif + + ldmtr = par->pd->ldmtr; + + if (!(vm->sync & FB_SYNC_HOR_HIGH_ACT)) + ldmtr |= LDMTR_CL1POL; + if (!(vm->sync & FB_SYNC_VERT_HIGH_ACT)) + ldmtr |= LDMTR_FLMPOL; + + /* shut down LCDC before changing display parameters */ + sh7760fb_blank(FB_BLANK_POWERDOWN, info); + + iowrite16(par->pd->ldickr, par->base + LDICKR); /* pixclock */ + iowrite16(ldmtr, par->base + LDMTR); /* polarities */ + iowrite16(lddfr, par->base + LDDFR); /* color/depth */ + iowrite16((par->rot ? 1 << 13 : 0), par->base + LDSMR); /* rotate */ + iowrite16(par->pd->ldpmmr, par->base + LDPMMR); /* Power Management */ + iowrite16(par->pd->ldpspr, par->base + LDPSPR); /* Power Supply Ctrl */ + + /* display resolution */ + iowrite16(((htcn >> 3) - 1) | (((hdcn >> 3) - 1) << 8), + par->base + LDHCNR); + iowrite16(vdln - 1, par->base + LDVDLNR); + iowrite16(vtln - 1, par->base + LDVTLNR); + /* h/v sync signals */ + iowrite16((vsynp - 1) | ((vsynw - 1) << 12), par->base + LDVSYNR); + iowrite16(((hsynp >> 3) - 1) | (((hsynw >> 3) - 1) << 12), + par->base + LDHSYNR); + /* AC modulation sig */ + iowrite16(par->pd->ldaclnr, par->base + LDACLNR); + + stride = (par->rot) ? vtln : hdcn; + if (!gray) + stride *= (bpp + 7) >> 3; + else { + if (bpp == 1) + stride >>= 3; + else if (bpp == 2) + stride >>= 2; + else if (bpp == 4) + stride >>= 1; + /* 6 bpp == 8 bpp */ + } + + /* if rotated, stride must be power of 2 */ + if (par->rot) { + unsigned long bit = 1 << 31; + while (bit) { + if (stride & bit) + break; + bit >>= 1; + } + if (stride & ~bit) + stride = bit << 1; /* not P-o-2, round up */ + } + iowrite16(stride, par->base + LDLAOR); + + /* set display mem start address */ + sbase = (unsigned long)par->fbdma; + if (par->rot) + sbase += (hdcn - 1) * stride; + + iowrite32(sbase, par->base + LDSARU); + + /* + * for DSTN need to set address for lower half. + * I (mlau) don't know which address to set it to, + * so I guessed at (stride * yres/2). + */ + if (((ldmtr & 0x003f) >= LDMTR_DSTN_MONO_8) && + ((ldmtr & 0x003f) <= LDMTR_DSTN_COLOR_16)) { + + fb_dbg(info, " ***** DSTN untested! *****\n"); + + dstn_off = stride; + if (par->rot) + dstn_off *= hdcn >> 1; + else + dstn_off *= vdln >> 1; + + ldsarl = sbase + dstn_off; + } else + ldsarl = 0; + + iowrite32(ldsarl, par->base + LDSARL); /* mem for lower half of DSTN */ + + info->fix.line_length = stride; + + sh7760fb_check_var(&info->var, info); + + sh7760fb_blank(FB_BLANK_UNBLANK, info); /* panel on! */ + + fb_dbg(info, "hdcn : %6d htcn : %6d\n", hdcn, htcn); + fb_dbg(info, "hsynw : %6d hsynp : %6d\n", hsynw, hsynp); + fb_dbg(info, "vdln : %6d vtln : %6d\n", vdln, vtln); + fb_dbg(info, "vsynw : %6d vsynp : %6d\n", vsynw, vsynp); + fb_dbg(info, "clksrc: %6d clkdiv: %6d\n", + (par->pd->ldickr >> 12) & 3, par->pd->ldickr & 0x1f); + fb_dbg(info, "ldpmmr: 0x%04x ldpspr: 0x%04x\n", par->pd->ldpmmr, + par->pd->ldpspr); + fb_dbg(info, "ldmtr : 0x%04x lddfr : 0x%04x\n", ldmtr, lddfr); + fb_dbg(info, "ldlaor: %ld\n", stride); + fb_dbg(info, "ldsaru: 0x%08lx ldsarl: 0x%08lx\n", sbase, ldsarl); + + return 0; +} + +static const struct fb_ops sh7760fb_ops = { + .owner = THIS_MODULE, + FB_DEFAULT_IOMEM_OPS, + .fb_blank = sh7760fb_blank, + .fb_check_var = sh7760fb_check_var, + .fb_setcolreg = sh7760_setcolreg, + .fb_set_par = sh7760fb_set_par, +}; + +static void sh7760fb_free_mem(struct fb_info *info) +{ + struct sh7760fb_par *par = info->par; + + if (!info->screen_base) + return; + + dma_free_coherent(info->device, info->screen_size, + info->screen_base, par->fbdma); + + par->fbdma = 0; + info->screen_base = NULL; + info->screen_size = 0; +} + +/* allocate the framebuffer memory. This memory must be in Area3, + * (dictated by the DMA engine) and contiguous, at a 512 byte boundary. + */ +static int sh7760fb_alloc_mem(struct fb_info *info) +{ + struct sh7760fb_par *par = info->par; + void *fbmem; + unsigned long vram; + int ret, bpp; + + if (info->screen_base) + return 0; + + /* get color info from register value */ + ret = sh7760fb_get_color_info(info, par->pd->lddfr, &bpp, NULL); + if (ret) { + printk(KERN_ERR "colinfo\n"); + return ret; + } + + /* min VRAM: xres_min = 16, yres_min = 1, bpp = 1: 2byte -> 1 page + max VRAM: xres_max = 1024, yres_max = 1024, bpp = 16: 2MB */ + + vram = info->var.xres * info->var.yres; + if (info->var.grayscale) { + if (bpp == 1) + vram >>= 3; + else if (bpp == 2) + vram >>= 2; + else if (bpp == 4) + vram >>= 1; + } else if (bpp > 8) + vram *= 2; + if ((vram < 1) || (vram > 1024 * 2048)) { + fb_dbg(info, "too much VRAM required. Check settings\n"); + return -ENODEV; + } + + if (vram < PAGE_SIZE) + vram = PAGE_SIZE; + + fbmem = dma_alloc_coherent(info->device, vram, &par->fbdma, GFP_KERNEL); + if (!fbmem) + return -ENOMEM; + + if ((par->fbdma & SH7760FB_DMA_MASK) != SH7760FB_DMA_MASK) { + dma_free_coherent(info->device, vram, fbmem, par->fbdma); + dev_err(info->device, "kernel gave me memory at 0x%08lx, which is" + "unusable for the LCDC\n", (unsigned long)par->fbdma); + return -ENOMEM; + } + + info->screen_base = fbmem; + info->screen_size = vram; + info->fix.smem_start = (unsigned long)info->screen_base; + info->fix.smem_len = info->screen_size; + + return 0; +} + +static int sh7760fb_probe(struct platform_device *pdev) +{ + struct fb_info *info; + struct resource *res; + struct sh7760fb_par *par; + int ret; + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + if (unlikely(res == NULL)) { + dev_err(&pdev->dev, "invalid resource\n"); + return -EINVAL; + } + + info = framebuffer_alloc(sizeof(struct sh7760fb_par), &pdev->dev); + if (!info) + return -ENOMEM; + + par = info->par; + par->dev = pdev; + + par->pd = pdev->dev.platform_data; + if (!par->pd) { + dev_dbg(&pdev->dev, "no display setup data!\n"); + ret = -ENODEV; + goto out_fb; + } + + par->ioarea = request_mem_region(res->start, + resource_size(res), pdev->name); + if (!par->ioarea) { + dev_err(&pdev->dev, "mmio area busy\n"); + ret = -EBUSY; + goto out_fb; + } + + par->base = ioremap(res->start, resource_size(res)); + if (!par->base) { + dev_err(&pdev->dev, "cannot remap\n"); + ret = -ENODEV; + goto out_res; + } + + iowrite16(0, par->base + LDINTR); /* disable vsync irq */ + par->irq = platform_get_irq(pdev, 0); + if (par->irq >= 0) { + ret = request_irq(par->irq, sh7760fb_irq, 0, + "sh7760-lcdc", &par->vsync); + if (ret) { + dev_err(&pdev->dev, "cannot grab IRQ\n"); + par->irq = -ENXIO; + } else + disable_irq_nosync(par->irq); + } + + fb_videomode_to_var(&info->var, par->pd->def_mode); + + ret = sh7760fb_alloc_mem(info); + if (ret) { + dev_dbg(info->device, "framebuffer memory allocation failed!\n"); + goto out_unmap; + } + + info->pseudo_palette = par->pseudo_palette; + + /* fixup color register bitpositions. These are fixed by hardware */ + info->var.red.offset = 11; + info->var.red.length = 5; + info->var.red.msb_right = 0; + + info->var.green.offset = 5; + info->var.green.length = 6; + info->var.green.msb_right = 0; + + info->var.blue.offset = 0; + info->var.blue.length = 5; + info->var.blue.msb_right = 0; + + info->var.transp.offset = 0; + info->var.transp.length = 0; + info->var.transp.msb_right = 0; + + strcpy(info->fix.id, "sh7760-lcdc"); + + /* set the DON2 bit now, before cmap allocation, as it will randomize + * palette memory. + */ + iowrite16(LDCNTR_DON2, par->base + LDCNTR); + info->fbops = &sh7760fb_ops; + + ret = fb_alloc_cmap(&info->cmap, 256, 0); + if (ret) { + dev_dbg(&pdev->dev, "Unable to allocate cmap memory\n"); + goto out_mem; + } + + ret = register_framebuffer(info); + if (ret < 0) { + dev_dbg(&pdev->dev, "cannot register fb!\n"); + goto out_cmap; + } + platform_set_drvdata(pdev, info); + + printk(KERN_INFO "%s: memory at phys 0x%08lx-0x%08lx, size %ld KiB\n", + pdev->name, + (unsigned long)par->fbdma, + (unsigned long)(par->fbdma + info->screen_size - 1), + info->screen_size >> 10); + + return 0; + +out_cmap: + sh7760fb_blank(FB_BLANK_POWERDOWN, info); + fb_dealloc_cmap(&info->cmap); +out_mem: + sh7760fb_free_mem(info); +out_unmap: + if (par->irq >= 0) + free_irq(par->irq, &par->vsync); + iounmap(par->base); +out_res: + release_mem_region(res->start, resource_size(res)); +out_fb: + framebuffer_release(info); + return ret; +} + +static void sh7760fb_remove(struct platform_device *dev) +{ + struct fb_info *info = platform_get_drvdata(dev); + struct sh7760fb_par *par = info->par; + + sh7760fb_blank(FB_BLANK_POWERDOWN, info); + unregister_framebuffer(info); + fb_dealloc_cmap(&info->cmap); + sh7760fb_free_mem(info); + if (par->irq >= 0) + free_irq(par->irq, &par->vsync); + iounmap(par->base); + release_mem_region(par->ioarea->start, resource_size(par->ioarea)); + framebuffer_release(info); +} + +static struct platform_driver sh7760_lcdc_driver = { + .driver = { + .name = "sh7760-lcdc", + }, + .probe = sh7760fb_probe, + .remove = sh7760fb_remove, +}; + +module_platform_driver(sh7760_lcdc_driver); + +MODULE_AUTHOR("Nobuhiro Iwamatsu, Manuel Lauss"); +MODULE_DESCRIPTION("FBdev for SH7760/63 integrated LCD Controller"); +MODULE_LICENSE("GPL v2"); -- cgit v1.3.1