Overview
| Comment: | add kmlini() and kmlina() functions; restructure allocation functions to work more reasonably (returning a tuple struct instead of making a user pass in a void**); update docs accordingly |
|---|---|
| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA3-256: |
acb4a9944e5a48cbab044b5ec26e8224 |
| User & Date: | lexi on 2019-08-22 08:44:29 |
| Other Links: | manifest | tags |
Context
|
2019-08-22
| ||
| 08:45 | check in missing files check-in: 269baab90a user: lexi tags: trunk | |
| 08:44 | add kmlini() and kmlina() functions; restructure allocation functions to work more reasonably (returning a tuple struct instead of making a user pass in a void**); update docs accordingly check-in: acb4a9944e user: lexi tags: trunk | |
| 04:31 | finish moving heap allocation/free functions to the posix syscall apparatus and deprecate the direct assembly implementations of platform_mmap; update the kmem docs to match new function signatures (and remove typos) check-in: 709ffb094d user: lexi tags: trunk | |
Changes
Modified arch/posix/syscalls from [24a70b57fd] to [f436d656b4].
1 1 exit 2 2 read 3 3 write 4 4 mmap 5 5 munmap 6 +brk
Modified mod/kcore/testbin.exe.c from [ae0ed8cd11] to [2c9c964882].
18 18 19 19 if (kiosend(e.std, ptr, null) == kiocond_ok) { 20 20 /* great, continue */ 21 21 } else { 22 22 return kbad_io; 23 23 } 24 24 25 - void* region; 26 - kmcond alloc = kmheapa(®ion, 2048); 27 - if (alloc != kmcond_ok) return kbad_mem; 28 - 25 + kmres alloc = kmheapa(2048); 26 + if (alloc.cond != kmcond_ok) return kbad_mem; 27 + 28 + void* region = alloc.raw; 29 29 kmzero(region,2048); 30 30 31 31 if (kmheapf(region) >= kmcond_fail) return kbad_mem; 32 32 33 33 return kbad_ok; 34 34 }
Modified mod/kmem/free.fn.c from [cc32756862] to [bac849b7ff].
8 8 * kmfree() frees memory allocated in any manner. 9 9 * it ignores non-dynamically allocated memory, 10 10 * returning kmcond_unnecessary. to check for 11 11 * success, compare result < kmcond_fail. 12 12 */ 13 13 14 14 kmcond kmfree(kmptr ptr) { 15 - if (ptr.kind <= kmkind_fail) return kmcond_unnecessary; 15 + if (ptr.kind <= kmkind_broken) return kmcond_unnecessary; 16 16 switch (ptr.kind) { 17 17 case kmkind_heap: return kmheapf(ptr.ref); 18 18 } 19 19 20 20 return kmcond_unhandled; 21 21 } 22 22
Modified mod/kmem/heapa.fn.c from [c8ccec879e] to [c08b42ee14].
16 16 #include <error_table.h> 17 17 18 18 /* we define all our platform functions here, whether or not 19 19 * they're for the correct platform - only the ones that are 20 20 * called by the preprocessed form of the code will actually 21 21 * be linked, linker errors are our friend here! */ 22 22 23 -kmcond kmheapa(void** where, sz len) { 23 +kmres kmheapa(sz len) { 24 24 /* allocate an object on the heap and return 25 25 * a pointer, or NULL if the allocation failed. */ 26 26 union { 27 27 void* raw; 28 28 ubyte* byte; 29 29 kmbox* header; 30 30 } region; 31 31 /* we need to allocate space for the 32 32 * header and for the actual object */ 33 33 sz region_size = sizeof(kmbox) + len; 34 + kmres reply; 34 35 35 36 # ifdef KFenv_posix 36 37 /* posix APIs - we've got it easy. currently for 37 38 * nonlinear heap allocation kmheapa simply uses 38 39 * m(un)map and lets the kernel worry about it. it 39 40 * may ultimately be worth replacing this with a 40 41 * more sophisticated implementation, most likely an ................................................................................ 64 65 * a value of -1 */ 65 66 66 67 struct k_platform_syscall_answer r = k_platform_syscall 67 68 (k_platform_syscall_mmap, Kmsz(args), args); 68 69 69 70 if (r.error == 0) region.byte = (ubyte*)r.ret; else { 70 71 switch (r.error) { 71 - case k_platform_error_EAGAIN: return kmcond_bad_lock; 72 - case k_platform_error_EINVAL: return kmcond_bad_size; 73 - case k_platform_error_EMFILE: return kmcond_too_many; 74 - case k_platform_error_ENOMEM: return kmcond_no_room; 75 - default: return kmcond_fail_assert; 72 + case k_platform_error_EAGAIN: reply.cond = kmcond_bad_lock; break; 73 + case k_platform_error_EINVAL: reply.cond = kmcond_bad_size; break; 74 + case k_platform_error_EMFILE: reply.cond = kmcond_too_many; break; 75 + case k_platform_error_ENOMEM: reply.cond = kmcond_no_room; break; 76 + default: reply.cond = kmcond_fail_assert; 76 77 } 78 + reply.raw = (void*)0; 79 + return reply; 77 80 } 78 81 # else 79 82 Knoimpl(kmheapa,KVos); 80 83 # error missing implementation 81 84 # endif 82 85 83 86 void* const object = (region.byte + sizeof (kmbox)); 84 87 85 88 region.header -> kind = kmkind_heap; 86 89 region.header -> size = len; 87 90 88 - *where = object; 89 - return kmcond_ok; 91 + reply.cond = kmcond_ok; 92 + reply.raw = object; 93 + 94 + return reply; 90 95 }
Modified mod/kmem/heapo.fn.c from [70c3679214] to [5d74e5db6e].
3 3 /* heapo.fn.c - kmheapo() "allocate heap object" 4 4 * ~ lexi hale <lexi@hale.su> 5 5 * kmheapo() allocates a region in heap memory 6 6 * and returns a kmptr struct referencing that 7 7 * newly allocated region. 8 8 */ 9 9 10 -kmcond kmheapo(kmptr* where, sz size) { 11 - void* ptr; 12 - kmcond e = kmheapa(&ptr, size); 13 - if (e != kmcond_ok) return e; 10 +kmres kmheapo(sz size) { 11 + kmres e = kmheapa(size); 12 + kmres reply; 13 + 14 + if (e.cond != kmcond_ok) { 15 + reply.cond = e.cond; 16 + reply.ptr.ref = (void*)0; 17 + reply.ptr.kind = kmkind_broken; 18 + return reply; 19 + } 20 + 14 21 kmptr p = { 15 - .kind = (ptr != null ? kmkind_heap : kmkind_fail), 16 - .ref = ptr, 22 + .kind = (e.raw != null ? kmkind_heap : kmkind_broken), 23 + .ref = e.raw, 17 24 .shred = false, 18 25 }; 19 - *where = p; 20 - return kmcond_ok; 26 + 27 + reply.ptr = p; 28 + reply.cond = kmcond_ok; 29 + return reply; 21 30 }
Modified mod/kmem/kmem.md from [0e44a94bf4] to [35f7501adf].
1 1 # kmem 2 2 3 3 **kmem** is a libk module that contains various functions for memory allocation and deallocation. it uses the **short** naming convention with the glyph `m`. 4 4 5 5 # description 6 6 7 -kmem allocators can work in several different ways. they can allocate memory directly from the heap (like `kmheapa()` and `kmlina()`), use a header that has already been allocated by another function, or allocate memory only from a pre-allocated pool. linear allocation with pool allocation is particularly useful, as it permits the very rapid allocation and deallocation of lots of objects with only a few adjustments to the heap, and no possibility of fragmentation or need for expensive algorithms like `malloc()` or `kmheapa()` 7 +kmem allocators can work in several different ways. they can allocate memory directly from the heap (like `kmheapa()` and `kmlina()`), use a header that has already been allocated by another function, or allocate memory only from a pre-allocated pool. linear allocation with pool allocation is particularly useful, as it permits the very rapid allocation and deallocation of lots of objects with only a few adjustments to the heap, and no possibility of fragmentation or need for expensive algorithms like `malloc()` or `kmheapa()`. functions that can return a value and an error condition always return a value of type `kmres`, a struct that contains the field `kmcond` with an error code, and one of `raw` (for functions that return raw pointers) or `ptr` (for functions that return `kmptr` objects). 8 8 9 9 # module functions 10 10 11 11 kmem supplies two module-level functions, used to interact with the `kmptr` container type. 12 12 13 13 * `kmfree(kmptr) → kmcond` - free, downref, or ignore the passed object as appropriate 14 14 * `kmshred(kmptr) → void` - free, downref, or zero the passed object as appropriate. if downref'ing, mark underlying object to be shredded. otherwise, zero its contents, then deallocate if appropriate. ................................................................................ 109 109 110 110 # naming convention 111 111 112 112 kmem function names are based on the **method** of allocation and the **action** being performed. methods are listed in the section below. kmem defines a number of standardized actions, though not every method uses every action. the character listed in brackets is suffixed to the name of the method to produce a function name: for instance, `kmheapa` will allocate memory on the heap, while `kmrefd` will decrement the reference count of its argument. 113 113 114 114 * initialize [i] - initializes a memory store on the heap 115 115 * initialize fixed [if] - initialize a memory store on the stack or in a fixed-size global 116 - * allocate [a] -a llocate a new region of memory of the given size, ready to write, and write a pointer to it into argument `where`. returns a value of `kmcond`; always check this to ensure allocation succeeded. contents of that region undefined. takes parameters `void** where, size_t sz`. 117 - * allocate pointer object [o] - like *allocate*, but fills in a `kmptr` instead of a raw `void*`. takes parameters `kmptr* where, size_t sz`. 116 + * allocate [a] - allocate a new region of memory of the given size, ready to write, and return a struct `kmres` containing an error code and, if the call succeeded, a pointer in the field `raw`. always check the `cond` field of its return value to ensure allocation succeeded. contents of the region specified by the `raw` field are undefined. takes parameter `size_t sz`. 117 + * allocate pointer object [o] - like *allocate*, but yields a `kmptr` in the `ptr` field of its return value instead of a raw `void*`. takes parameters `size_t sz`. 118 118 * zero [z] - allocate a new region of memory and zero it before returning it for writing. 119 119 * zero pointer object [zo] - like *zero*, but returns a `kmptr` instead of a raw `void*`. 120 120 * free [f] - free a section of memory, either decrementing a reference count or returning it to whatever pool it came from. 121 121 * shred [s] - destroy whatever was in the segment of memory, then return it to the pool it came from. 122 122 * destroy [x] - tears down a memory store 123 123 * upref [u] - increments a reference counter 124 124 125 125 ## methods 126 126 127 127 kmem currently supports the following methods of memory management, along with which methods are defined for it. (note that `a` implies `z` and `f` implies `s`). a method may be excluded from a libk binary by defining the flag `KFmem_no[name]`, e.g. `KFmem_noheap`. 128 128 129 129 the fastest allocator is the linear allocator, which should be sufficient for most simple programs. it allocates and deallocates memory simply by resizing the stack; there is no fragmentation, but objects must be freed in the order they are allocated. however, entire groups of objects can be freed at once at very little cost. 130 130 131 +**caveat scriptor:** the linear allocation method is unfortunately complicated by the fact that the methods it uses make it fundamentally incompatible with use in the program of the "malloc" allocator used by libc. this should not be a problem for programs that only link libk, but if they link in any external libraries that depend on libc and which use malloc internally, **the linear allocator cannot be used.** 132 + 131 133 * `lin` [iax] - linear heap allocator 132 - * `kmlini(void) → void*` - return a pointer to the current top of the heap 133 - * `kmlina(size_t) → void*` - allocate space on the heap and increase its size appropriately 134 - * `kmlinz(size_t) → void*` - allocate zero-filled space on the heap and increase its size appropriately 135 - * `kmlinx(void*) → void*` - returns the top of the heap to the location specified, freeing all memory allocated since the call to kmlini() or `kmlina()` that produced it 134 + * `kmlini` - return a pointer to the current top of the heap 135 + * `kmlina` - allocate space on the heap and increase its size appropriately 136 + * `kmlinz` - allocate zero-filled space on the heap and increase its size appropriately 137 + * `kmlinx` - returns the top of the heap to the location specified, freeing all memory allocated since the call to kmlini() or `kmlina()` that produced it 136 138 * `heap` [af] - random heap allocation 137 - * `kmheapa(size_t) → void*` - allocate 138 - * `kmheapz(size_t) → void*` - zero-allocate 139 - * `kmheapao(size_t) → kmptr` - allocate pointer object 140 - * `kmheapzo(size_t) → kmptr` - zero-allocate pointer object 141 - * `kmheapf(void*) → void` - free 142 - * `kmheaps(void*) → void` - shred 139 + * `kmheapa` - allocate 140 + * `kmheapz` - zero-allocate 141 + * `kmheapo` - allocate pointer object 142 + * `kmheapzo` - zero-allocate pointer object 143 + * `kmheapf` - free 144 + * `kmheaps` - shred 143 145 * `ref` [afu] - reference-counted heap object 144 - * `kmrefa(kmcell*, size_t) → void*` - allocate 145 - * `kmrefz(kmcell*, size_t) → void*` - zero-allocate 146 - * `kmrefao(kmcell*, size_t) → void*` - allocate pointer object 147 - * `kmrefzo(kmcell*, size_t) → void*` - zero-allocate pointer object 148 - * `kmreff(void*) → void` - downref; free if last ref 149 - * `kmrefs(void*) → void` - downref and mark for shred on last ref 146 + * `kmrefa` - allocate 147 + * `kmrefz` - zero-allocate 148 + * `kmrefo` - allocate pointer object 149 + * `kmrefzo` - zero-allocate pointer object 150 + * `kmreff` - downref; free if last ref 151 + * `kmrefs` - downref and mark for shred on last ref 150 152 * `pool` [ixaf] - memory pool 151 153 * `kmpooli(kmcell*, size_t sz, size_t n) → kmpool*` - initialize a fixed memory pool (a pool of `n` cells of length `sz`) 152 - * `kmpoolx(kmpool*) → void` - tear down a memory pool 153 - * `kmpoola(kmpool*) → void*` - allocate from pool 154 - * `kmpoolz(kmpool*, size_t) → void*` - zero-allocate from pool 155 - * `kmpoolao(kmpool*, size_t) → void*` - allocate pointer object 156 - * `kmpoolzo(kmpool*, size_t) → void*` - zero-allocate pointer object 157 - * `kmpoolf(void*) → void` - downref; free if last ref 158 - * `kmpools(void*) → void` - downref and mark for shred on last ref 154 + * `kmpoolx` - tear down a memory pool 155 + * `kmpoola` - allocate from pool 156 + * `kmpoolz` - zero-allocate from pool 157 + * `kmpoolo` - allocate pointer object 158 + * `kmpoolzo` - zero-allocate pointer object 159 + * `kmpoolf` - downref; free if last ref 160 + * `kmpools` - downref and mark for shred on last ref 159 161 * `tree` [af] - uses a node-child strategy. when a node is freed, all of its children are automatically freed as well. 160 - * `kmtreea(kmcell* src, void* parent, size_t) → void*` - create a tree node. if `parent` is NULL, the node will the top of a new tree. if src is null, allocate on-heap. 161 - * `kmtreez(kmcell* src, void* parent, size_t) → void*` - like `kmtreea` but zeroed 162 - * `kmtreeao(kmcell* src, void* parent, size_t) → kmptr` - like `kmtreea` but returns a `kmptr` 163 - * `kmtreezo(kmcell* src, void* parent, size_t) → kmptr` - like `kmtreez` but returns a `kmptr` 164 - * `kmtreef(void*) → kmptr` - frees a node and all its children 162 + * `kmtreea` - create a tree node. if `parent` is NULL, the node will the top of a new tree. if src is null, allocate on-heap. 163 + * `kmtreez` - like `kmtreea` but zeroed 164 + * `kmtreeao` - like `kmtreea` but returns a `kmptr` 165 + * `kmtreezo` - like `kmtreez` but returns a `kmptr` 166 + * `kmtreef` - frees a node and all its children 165 167 166 168 ## macros 167 169 168 170 kmem defines the following macros. 169 171 170 172 * `Kmsz(array)` - a convenience macro to return the number of elements in a static array. inserts the text `( sizeof (array) / sizeof (array) [0] )` 171 173 * `Kmszs(type, struct)` - a convenience macro to return the size of a struct. requires compound literals. 172 174 * `Kmszsa(type, array)` - calculates the number of elements in an array of a given struct type. inserts the text `( sizeof ( (type) array ) / sizeof (type) )` 173 175 * `Kmpsa(type, struct)` - a convenience macro to insert a "pascal struct array" - that is, a struct array prefixed with a size value. this is equivalent to `Kmszsa(type, array), array`
Modified mod/kmem/mem.h from [d8d36f64f5] to [0dc09a3b20].
27 27 /* when something truly should 28 28 * never happen: */ 29 29 kmcond_fail_assert, 30 30 } kmcond; 31 31 32 32 typedef enum kmkind { 33 33 kmkind_none, 34 - kmkind_fail, 34 + kmkind_broken, 35 35 kmkind_linear, 36 36 kmkind_heap, 37 37 kmkind_pool, 38 38 kmkind_ref, 39 39 kmkind_tree 40 40 } kmkind; 41 41 ................................................................................ 66 66 67 67 typedef struct kmptr { 68 68 kmkind kind; 69 69 kmshred shred; 70 70 void* ref; 71 71 } kmptr; 72 72 73 +/* this struct is used to return both a pointer 74 + * and an error value at the same time. */ 75 +typedef struct kmres { 76 + kmcond cond; 77 + union { 78 + void* raw; 79 + kmptr ptr; 80 + }; 81 +} kmres; 73 82 /* heap functions */ 74 83 75 -kmcond kmheapa (void**, sz); 76 -kmcond kmheapao(kmptr*, sz); 84 +kmres kmheapa (sz); 85 +kmres kmheapo (sz); 77 86 kmcond kmheapf (void*); 87 +kmres kmlina (sz); 88 +void* kmlini (void); 78 89 79 90 /* generic functions */ 80 91 81 92 kmcond kmfree(kmptr); 82 -kmkind kmtell(void*); 83 93 void kmzero(void*,sz); 84 94 void kmozero(kmptr); 85 95 86 96 87 97 #ifdef __cplusplus 88 98 } 89 99 #endif 90 100 91 101 #endif