0
我有一個SRAM存儲器可在PCI欄1尋址。我想知道如何在驅動程序中正確寫入mmap函數，以便我的用戶進程可以映射sram內存並讀/寫它。如何實現PCI條形內存的mmap？
我寫了下面的探頭和MMAP功能驅動程序做相同的：
的探測功能：
static int probe(struct pci_dev * pcidev, const struct pci_device_id * id)
{
int r,i;
unsigned long start,end;
int sram;
r = pci_enable_device(pcidev);
if(r < 0)
{
printk(KERN_ALERT DEVICE_NAME ": Enable of my_pci device fails %d\n",r);
return -1;
}
pci_set_master(pcidev);
start = pci_resource_start(pcidev, 1);
end = pci_resource_end(pcidev, 1);
size = end - start + 1;
sram_raw_base_address = start;
sram_base_address = (unsigned long)ioremap_nocache(start,size);
sram_size = size;
}
MMAP的功能是：
static int my_mmap(struct file *file, struct vm_area_struct *vma)
{
size_t size = vma->vm_end - vma->vm_start;
unsigned long ioaddress, iosize;
if(vma->vm_end < vma->vm_start)
{
return -EAGAIN;
}
/* mapping sram. */
ioaddress = sram_base_address;
iosize = sram_size;
/* simple check to prevent mapping past io area. */
if((size > iosize) ||
((vma->vm_pgoff << PAGE_SHIFT) > iosize) ||
(((vma->vm_pgoff << PAGE_SHIFT)+size) > iosize))
{
return -EINVAL;
}
if (remap_pfn_range(vma,vma->vm_start,vmalloc_to_pfn(ioaddress+(vma->vm_pgoff << PAGE_SHIFT)),
size,vma->vm_page_prot)) {
return -EAGAIN;
}
vma->vm_ops = &vmops;
vmops_open(vma);
return 0;
}
每當我試着在我的應用程序中映射SRAM內存時，在/ var/log/syslog中出現以下錯誤：
Jul 26 13:21:12 manik kernel: [86635.262485] my_pci my_mmap - called
Jul 26 13:21:12 manik kernel: [86635.262524] BUG: unable to handle kernel paging request at 02530000
Jul 26 13:21:12 manik kernel: [86635.262549] IP: [<c11ab31d>] vmalloc_to_pfn+0xd/0x30
Jul 26 13:21:12 manik kernel: [86635.262569] *pdpt = 00000000050f8001 *pde = 0000000000000000
Jul 26 13:21:12 manik kernel: [86635.262584] Oops: 0000 [#1] SMP
Jul 26 13:21:12 manik kernel: [86635.262595] Modules linked in: qcomdl(POE) gdapdl(POE) gammadl(POE) aspdl(POE) ccce(POE) scard(POE) kmikohn(OE) fmon(OE) khcd(OE) kcid(OE) kspi(POE) kpwrfail(OE) mk7i_pci(OE) snd_usb_audio input_leds hid_multitouch joydev snd_usbmidi_lib intel_rapl x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel kvm i2c_ocores snd_soc_rt5640 snd_hda_codec_hdmi irqbypass crc32_pclmul snd_soc_rl6231 snd_hda_intel snd_hda_codec lpc_ich ie31200_edac edac_core snd_hda_core shpchp snd_hwdep snd_soc_core snd_compress ac97_bus snd_pcm_dmaengine 8250_fintek snd_pcm snd_seq_midi snd_seq_midi_event snd_rawmidi snd_seq snd_seq_device snd_timer snd snd_soc_sst_acpi soundcore 8250_dw dw_dmac soc_button_array dw_dmac_core elan_i2c spi_pxa2xx_platform i2c_designware_platform i2c_designware_core mac_hid parport_pc ppdev lp parport autofs4 nouveau mxm_wmi i915 wmi i2c_algo_bit ttm ahci libahci drm_kms_helper syscopyarea e1000e sysfillrect sysimgblt fb_sys_fops ptp drm pps_core sdhci_acpi video i2c_hid sdhci fjes hid_generic usbhid hid [last unloaded: mk7i_pci]
Jul 26 13:21:12 manik kernel: [86635.262938] CPU: 0 PID: 14025 Comm: test_sram Tainted: P W IOE 4.4.0-31-generiC#50
Jul 26 13:21:12 manik kernel: [86635.262950] Hardware name: ADLINK Technology Inc. Express-HL./SHARKBAY, BIOS 1.14 01/01/2013
Jul 26 13:21:12 manik kernel: [86635.262962] task: d0c05a00 ti: ca928000 task.ti: ca928000
Jul 26 13:21:12 manik kernel: [86635.262972] EIP: 0060:[<c11ab31d>] EFLAGS: 00010246 CPU: 0
Jul 26 13:21:12 manik kernel: [86635.262983] EIP is at vmalloc_to_pfn+0xd/0x30
Jul 26 13:21:12 manik kernel: [86635.262991] EAX: 02530000 EBX: c5617138 ECX: ee9d9000 EDX: fff1b000
Jul 26 13:21:12 manik kernel: [86635.263001] ESI: 02000000 EDI: f3200000 EBP: ca929e70 ESP: ca929e70
Jul 26 13:21:12 manik kernel: [86635.263010] DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
Jul 26 13:21:12 manik kernel: [86635.263019] CR0: 80050033 CR2: 02530000 CR3: 2dc02500 CR4: 001406f0
Jul 26 13:21:12 manik kernel: [86635.263028] Stack:
Jul 26 13:21:12 manik kernel: [86635.263034] ca929e90 f0c566af f0c58260 024080c0 c5617138 c56171b4 b00 c56171b0
Jul 26 13:21:12 manik kernel: [86635.263063] ca929ee4 c11a64f8 b00 000000fb 00000000 c6eac0c0 00000000 00000000
Jul 26 13:21:12 manik kernel: [86635.263091] 00000000 00000008 00000000 00000000 c56171b4 00002000 c6eac0c0 c5617138
Jul 26 13:21:12 manik kernel: [86635.263120] Call Trace:
Jul 26 13:21:12 manik kernel: [86635.263132] [<f0c566af>] my_mmap+0x6f/0xf0 [mk7i_pci]
Jul 26 13:21:12 manik kernel: [86635.263145] [<c11a64f8>] mmap_region+0x388/0x590
Jul 26 13:21:12 manik kernel: [86635.263155] [<c11a6956>] do_mmap+0x256/0x360
Jul 26 13:21:12 manik kernel: [86635.263167] [<c118d19a>] vm_mmap_pgoff+0x9a/0xc0
Jul 26 13:21:12 manik kernel: [86635.263177] [<c11a4c54>] SyS_mmap_pgoff+0x194/0x230
Jul 26 13:21:12 manik kernel: [86635.263190] [<c100393d>] do_fast_syscall_32+0x8d/0x150
Jul 26 13:21:12 manik kernel: [86635.263202] [<c17b229c>] sysenter_past_esp+0x3d/0x61
Jul 26 13:21:12 manik kernel: [86635.] Code: 8b 80 c0 20 d2 c1 83 e0 fc 8d 1c d0 eb bb 31 db 89 d8 5b 5e 5f 5d c3 8d b4 26 00 00 00 00 55 89 e5 3e 8d 74 26 00 e8 d3 fe ff ff <8b> 10 5d c1 ea 19 c1 e2 04 8b 92 c0 20 d2 c1 83 e2 fc 29 d0 c1
Jul 26 13:21:12 manik kernel: [86635.263388] EIP: [<c11ab31d>] vmalloc_to_pfn+0xd/0x30 SS:ESP 0068:ca929e70
Jul 26 13:21:12 manik kernel: [86635.263406] CR2: 0000000002530000
Jul 26 13:21:12 manik kernel: [86635.269070] ---[ end trace f85e2d73d203ae00 ]---
顯然，驅動程序的mmap函數在調用vmalloc_to_pfn時失敗。 我不明白爲什麼。
我在探測功能中使用ioremap_nocache來創建不可緩存的虛擬地址，因爲我希望PCI條存儲器區域的讀/寫操作可以在內存硬件而不是cpu緩存中讀/寫。我希望我做對了。
現在，對於mmap調用，我使用vmalloc_to_pfn來獲取物理頁面幀號。
有什麼我在這裏做錯了嗎？
您爲'ioremap_nocache'顯示的參數顯然是錯誤的;它只需要兩個參數 - 一個phys地址和一個大小。我不明白它是如何實際編譯的。 –
此外，如果您首先調用'vmalloc_to_pfn'和'printk'結果來查看您傳遞給'remap_pfn_range'的具體內容，可能會有所幫助。 –
感謝您指出'ioremap_nocache'問題中的錯誤參數。 好吧，根據它的文檔'vmalloc_to_pfn'爲我們提供了傳遞給它的虛擬地址的物理幀號。代碼與Linux內核3.9.2一起工作，但不再與Linux 4.4.0 – Monku