This commit removes all traces of Minix segments (the text/data/stack memory map abstraction in the kernel) and significance of Intel segments (hardware segments like CS, DS that add offsets to all addressing before page table translation). This ultimately simplifies the memory layout and addressing and makes the same layout possible on non-Intel architectures. There are only two types of addresses in the world now: virtual and physical; even the kernel and processes have the same virtual address space. Kernel and user processes can be distinguished at a glance as processes won't use 0xF0000000 and above. No static pre-allocated memory sizes exist any more. Changes to booting: . The pre_init.c leaves the kernel and modules exactly as they were left by the bootloader in physical memory . The kernel starts running using physical addressing, loaded at a fixed location given in its linker script by the bootloader. All code and data in this phase are linked to this fixed low location. . It makes a bootstrap pagetable to map itself to a fixed high location (also in linker script) and jumps to the high address. All code and data then use this high addressing. . All code/data symbols linked at the low addresses is prefixed by an objcopy step with __k_unpaged_*, so that that code cannot reference highly-linked symbols (which aren't valid yet) or vice versa (symbols that aren't valid any more). . The two addressing modes are separated in the linker script by collecting the unpaged_*.o objects and linking them with low addresses, and linking the rest high. Some objects are linked twice, once low and once high. . The bootstrap phase passes a lot of information (e.g. free memory list, physical location of the modules, etc.) using the kinfo struct. . After this bootstrap the low-linked part is freed. . The kernel maps in VM into the bootstrap page table so that VM can begin executing. Its first job is to make page tables for all other boot processes. So VM runs before RS, and RS gets a fully dynamic, VM-managed address space. VM gets its privilege info from RS as usual but that happens after RS starts running. . Both the kernel loading VM and VM organizing boot processes happen using the libexec logic. This removes the last reason for VM to still know much about exec() and vm/exec.c is gone. Further Implementation: . All segments are based at 0 and have a 4 GB limit. . The kernel is mapped in at the top of the virtual address space so as not to constrain the user processes. . Processes do not use segments from the LDT at all; there are no segments in the LDT any more, so no LLDT is needed. . The Minix segments T/D/S are gone and so none of the user-space or in-kernel copy functions use them. The copy functions use a process endpoint of NONE to realize it's a physical address, virtual otherwise. . The umap call only makes sense to translate a virtual address to a physical address now. . Segments-related calls like newmap and alloc_segments are gone. . All segments-related translation in VM is gone (vir2map etc). . Initialization in VM is simpler as no moving around is necessary. . VM and all other boot processes can be linked wherever they wish and will be mapped in at the right location by the kernel and VM respectively. Other changes: . The multiboot code is less special: it does not use mb_print for its diagnostics any more but uses printf() as normal, saving the output into the diagnostics buffer, only printing to the screen using the direct print functions if a panic() occurs. . The multiboot code uses the flexible 'free memory map list' style to receive the list of free memory if available. . The kernel determines the memory layout of the processes to a degree: it tells VM where the kernel starts and ends and where the kernel wants the top of the process to be. VM then uses this entire range, i.e. the stack is right at the top, and mmap()ped bits of memory are placed below that downwards, and the break grows upwards. Other Consequences: . Every process gets its own page table as address spaces can't be separated any more by segments. . As all segments are 0-based, there is no distinction between virtual and linear addresses, nor between userspace and kernel addresses. . Less work is done when context switching, leading to a net performance increase. (8% faster on my machine for 'make servers'.) . The layout and configuration of the GDT makes sysenter and syscall possible.
131 lines
3.7 KiB
C
131 lines
3.7 KiB
C
/* The kernel call implemented in this file:
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* m_type: SYS_VUMAP
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*
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* The parameters for this kernel call are:
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* m10_i1: VUMAP_ENDPT (grant owner, or SELF for local addresses)
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* m10_l1: VUMAP_VADDR (address of virtual (input) vector)
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* m10_i2: VUMAP_VCOUNT (number of elements in virtual vector)
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* m10_l2: VUMAP_OFFSET (offset into first entry of input vector)
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* m10_i3: VUMAP_ACCESS (safecopy access requested for input)
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* m10_l3: VUMAP_PADDR (address of physical (output) vector)
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* m10_i4: VUMAP_PMAX (maximum number of physical vector elements)
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* m10_i1: VUMAP_PCOUNT (upon return: number of elements filled)
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*/
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#include "kernel/system.h"
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#include <assert.h>
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/*===========================================================================*
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* do_vumap *
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*===========================================================================*/
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int do_vumap(struct proc *caller, message *m_ptr)
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{
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/* Map a vector of grants or local virtual addresses to physical addresses.
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* Designed to be used by drivers to perform an efficient lookup of physical
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* addresses for the purpose of direct DMA from/to a remote process.
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*/
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endpoint_t endpt, source, granter;
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struct proc *procp;
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struct vumap_vir vvec[MAPVEC_NR];
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struct vumap_phys pvec[MAPVEC_NR];
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vir_bytes vaddr, paddr, vir_addr;
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phys_bytes phys_addr;
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int i, r, proc_nr, vcount, pcount, pmax, access;
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size_t size, chunk, offset;
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endpt = caller->p_endpoint;
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/* Retrieve and check input parameters. */
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source = m_ptr->VUMAP_ENDPT;
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vaddr = (vir_bytes) m_ptr->VUMAP_VADDR;
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vcount = m_ptr->VUMAP_VCOUNT;
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offset = m_ptr->VUMAP_OFFSET;
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access = m_ptr->VUMAP_ACCESS;
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paddr = (vir_bytes) m_ptr->VUMAP_PADDR;
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pmax = m_ptr->VUMAP_PMAX;
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if (vcount <= 0 || pmax <= 0)
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return EINVAL;
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if (vcount > MAPVEC_NR) vcount = MAPVEC_NR;
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if (pmax > MAPVEC_NR) pmax = MAPVEC_NR;
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/* Convert access to safecopy access flags. */
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switch (access) {
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case VUA_READ: access = CPF_READ; break;
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case VUA_WRITE: access = CPF_WRITE; break;
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case VUA_READ|VUA_WRITE: access = CPF_READ|CPF_WRITE; break;
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default: return EINVAL;
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}
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/* Copy in the vector of virtual addresses. */
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size = vcount * sizeof(vvec[0]);
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if (data_copy(endpt, vaddr, KERNEL, (vir_bytes) vvec, size) != OK)
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return EFAULT;
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pcount = 0;
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/* Go through the input entries, one at a time. Stop early in case the output
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* vector has filled up.
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*/
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for (i = 0; i < vcount && pcount < pmax; i++) {
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size = vvec[i].vv_size;
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if (size <= offset)
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return EINVAL;
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size -= offset;
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if (source != SELF) {
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r = verify_grant(source, endpt, vvec[i].vv_grant, size, access,
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offset, &vir_addr, &granter);
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if (r != OK)
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return r;
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} else {
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vir_addr = vvec[i].vv_addr + offset;
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granter = endpt;
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}
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okendpt(granter, &proc_nr);
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procp = proc_addr(proc_nr);
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/* Each virtual range is made up of one or more physical ranges. */
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while (size > 0 && pcount < pmax) {
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chunk = vm_lookup_range(procp, vir_addr, &phys_addr, size);
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if (!chunk) {
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/* Try to get the memory allocated, unless the memory
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* is supposed to be there to be read from.
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*/
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if (access & CPF_READ)
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return EFAULT;
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/* This call may suspend the current call, or return an
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* error for a previous invocation.
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*/
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return vm_check_range(caller, procp, vir_addr, size);
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}
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pvec[pcount].vp_addr = phys_addr;
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pvec[pcount].vp_size = chunk;
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pcount++;
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vir_addr += chunk;
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size -= chunk;
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}
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offset = 0;
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}
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/* Copy out the resulting vector of physical addresses. */
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assert(pcount > 0);
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size = pcount * sizeof(pvec[0]);
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r = data_copy_vmcheck(caller, KERNEL, (vir_bytes) pvec, endpt, paddr, size);
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if (r == OK)
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m_ptr->VUMAP_PCOUNT = pcount;
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return r;
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}
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