Line data Source code
1 : #ifndef HEADER_fd_src_flamenco_vm_fd_vm_h
2 : #define HEADER_fd_src_flamenco_vm_fd_vm_h
3 :
4 : #include "fd_vm_base.h"
5 :
6 : /* A fd_vm_t is an opaque handle of a virtual machine that can execute
7 : sBPF programs. */
8 :
9 : struct fd_vm;
10 : typedef struct fd_vm fd_vm_t;
11 :
12 : /**********************************************************************/
13 : /* FIXME: MOVE TO FD_VM_PRIVATE WHEN CONSTRUCTORS READY */
14 :
15 : /* A fd_vm_shadow_t holds stack frame information not accessible from
16 : within a program. */
17 :
18 : struct fd_vm_shadow { ulong r6; ulong r7; ulong r8; ulong r9; ulong r10; ulong pc; };
19 : typedef struct fd_vm_shadow fd_vm_shadow_t;
20 :
21 : /* fd_vm_input_region_t holds information about fragmented memory regions
22 : within the larger input region. */
23 :
24 : struct __attribute__((aligned(8UL))) fd_vm_input_region {
25 : ulong vaddr_offset; /* Represents offset from the start of the input region. */
26 : ulong haddr; /* Host address corresponding to the start of the mem region. */
27 : uint region_sz; /* Size of the memory region. */
28 : uchar is_writable; /* If the region can be written to or is read-only */
29 : uchar is_acct_data; /* Set if this is an account data region (either orig data or resize buffer). */
30 : };
31 : typedef struct fd_vm_input_region fd_vm_input_region_t;
32 :
33 : /* fd_vm_acc_region_meta_t holds metadata about a given account. An array of these
34 : structs will map an instruction account index to its respective input memory
35 : region location. */
36 :
37 : struct __attribute((aligned(8UL))) fd_vm_acc_region_meta {
38 : uint region_idx;
39 : uchar has_data_region;
40 : uchar has_resizing_region;
41 : /* offset of the accounts metadata region, relative to the start of the input region.
42 : importantly, this excludes any duplicate account markers at the beginning of the "full" metadata region. */
43 : ulong metadata_region_offset;
44 : /* FIXME: We can get rid of this field once DM is activated. This is
45 : only a hack to make the non-DM code path happy. When DM is
46 : activated, we could query the input_mem_region array for the
47 : original data len. */
48 : ulong original_data_len;
49 : };
50 : typedef struct fd_vm_acc_region_meta fd_vm_acc_region_meta_t;
51 :
52 : /* In Agave, all the regions are 16-byte aligned in host address space. There is then an alignment check
53 : which is done inside each syscall memory translation, checking if the data is aligned in host address
54 : space. This is a layering violation, as it leaks the host address layout into the consensus model.
55 :
56 : In the future we will change this alignment check in the vm to purely operate on the virtual address space,
57 : taking advantage of the fact that Agave regions are known to be aligned. For now, we align our regions to
58 : either 8 or 16 bytes, as there are no 16-byte alignment translations in the syscalls currently:
59 : stack: 16 byte aligned
60 : heap: 16 byte aligned
61 : input: 8 byte aligned
62 : rodata: 8 byte aligned
63 :
64 : https://github.com/solana-labs/rbpf/blob/cd19a25c17ec474e6fa01a3cc3efa325f44cd111/src/ebpf.rs#L39-L40 */
65 411 : #define FD_VM_HOST_REGION_ALIGN (16UL)
66 :
67 : struct __attribute__((aligned(FD_VM_HOST_REGION_ALIGN))) fd_vm {
68 :
69 : /* VM configuration */
70 :
71 : /* FIXME: suspect these three should be replaced by some kind of VM
72 : enabled feature struct (though syscalls do seem to make additional
73 : non-trivial use of instr_ctx). */
74 :
75 : fd_exec_instr_ctx_t * instr_ctx; /* FIXME: DOCUMENT */
76 :
77 : /* FIXME: frame_max should be run time configurable by compute budget.
78 : If there is no reasonable upper bound on this, shadow and stack
79 : will need to be provided by users. */
80 :
81 : //ulong frame_max; /* Maximum number of stack frames, in [0,FD_VM_STACK_FRAME_MAX] */
82 : ulong heap_max; /* Maximum amount of heap in bytes, in [0,FD_VM_HEAP_MAX] */
83 : ulong entry_cu; /* Initial number of compute units for this program, in [0,FD_VM_COMPUTE_UNIT_LIMIT] */
84 :
85 : /* FIXME: The below are practically an exact match to the
86 : fields of an fd_sbpf_program_t (sans ELF info) */
87 :
88 : uchar const * rodata; /* Program read only data, indexed [0,rodata_sz), aligned 8 */
89 : ulong rodata_sz; /* Program read only data size in bytes, FIXME: BOUNDS? */
90 : ulong const * text; /* Program sBPF words, indexed [0,text_cnt), aligned 8 */
91 : ulong text_cnt; /* Program sBPF word count, all text words are inside the rodata */
92 : ulong text_off; /* ==(ulong)text - (ulong)rodata, relocation offset in bytes we must apply to indirect calls
93 : (callx/CALL_REGs), IMPORTANT SAFETY TIP! THIS IS IN BYTES, NOT WORDS! */
94 : ulong text_sz; /* Program sBPF size in bytes, == text_cnt*8 */
95 :
96 : ulong entry_pc; /* Initial program counter, in [0,text_cnt)
97 : FIXME: MAKE SURE NOT INTO MW INSTRUCTION, MAKE SURE VALID CALLDEST? */
98 : ulong const * calldests; /* Bit vector of local functions that can be called into, bit indexed in [0,text_cnt) */
99 : /* FIXME: ADD BIT VECTOR OF FORBIDDEN BRANCH TARGETS (E.G.
100 : INTO THE MIDDLE OF A MULTIWORD INSTRUCTION) */
101 :
102 : fd_sbpf_syscalls_t const * syscalls; /* The map of syscalls (sharable over multiple concurrently running vm) */
103 :
104 : fd_vm_trace_t * trace; /* Location to stream traces (no tracing if NULL) */
105 :
106 : /* VM execution and syscall state */
107 :
108 : /* These are used to communicate the execution and syscall state to
109 : users and syscalls. These are initialized based on the above when
110 : a program starts executing. When program halts or faults, these
111 : provide precise execution diagnostics to the user (and potential
112 : breakpoint/continue functionality in the future). When the vm
113 : makes a syscall, the vm will set these precisely and, when a
114 : syscall returns, the vm will update its internal execution state
115 : appropriately. */
116 :
117 : /* IMPORTANT SAFETY TIP! THE BEHAVIOR OF THE SYSCALL ALLOCATOR FOR
118 : HEAP_SZ MUST EXACTLY MATCH THE SOLANA VALIDATOR ALLOCATOR:
119 :
120 : https://github.com/solana-labs/solana/blob/v1.17.23/program-runtime/src/invoke_context.rs#L122-L148
121 :
122 : BIT-FOR-BIT AND BUG-FOR-BUG. SEE THE SYSCALL_ALLOC_FREE FOR MORE
123 : DETAILS. */
124 :
125 : ulong pc; /* The current instruction, in [0,text_cnt) in normal execution, may be out of bounds in a fault */
126 : ulong ic; /* The number of instructions which have been executed */
127 : ulong cu; /* The remaining CUs left for the transaction, positive in normal execution, may be zero in a fault */
128 : ulong frame_cnt; /* The current number of stack frames pushed, in [0,frame_max] */
129 :
130 : ulong heap_sz; /* Heap size in bytes, in [0,heap_max] */
131 :
132 : /* VM memory */
133 :
134 : /* The vm classifies the 64-bit vm address space into 6 regions:
135 :
136 : 0 - unmapped lo
137 : 1 - program -> [FD_VM_MEM_MAP_PROGRAM_REGION_START,FD_VM_MEM_MAP_PROGRAM_REGION_START+4GiB)
138 : 2 - stack -> [FD_VM_MEM_MAP_STACK_REGION_START, FD_VM_MEM_MAP_STACK_REGION_START +4GiB)
139 : 3 - heap -> [FD_VM_MEM_MAP_HEAP_REGION_START, FD_VM_MEM_MAP_HEAP_REGION_START +4GiB)
140 : 4 - input -> [FD_VM_MEM_MAP_INPUT_REGION_START, FD_VM_MEM_MAP_INPUT_REGION_START +4GiB)
141 : 5 - unmapped hi
142 :
143 : These mappings are encoded in a software TLB consisting of three
144 : 6-element arrays: region_haddr, region_ld_sz and region_st_sz.
145 :
146 : region_haddr[i] gives the location in host address space of the
147 : first byte in region i. region_{ld,st}_sz[i] gives the number of
148 : mappable bytes in this region for {loads,stores}. Note that
149 : region_{ld,st}_sz[i]<2^32. Further note that
150 : [region_haddr[i],region_haddr[i]+region_{ld,st}_sz[i]) does not
151 : wrap around in host address space and does not overlap with any
152 : other usages.
153 :
154 : region_{ld,st}_sz[0] and region_{ld,st}_sz[5] are zero such that
155 : requests to access data from a positive sz range in these regions
156 : will fail, making regions 0 and 5 unreadable and unwritable. As
157 : such, region_haddr[0] and region_haddr[5] are arbitrary; NULL is
158 : used as the obvious default.
159 :
160 : region_st_sz[1] is also zero such that requests to store data to
161 : any positive sz range in this region will fail, making region 1
162 : unwritable.
163 :
164 : When the direct mapping feature is enabled, the input region will
165 : no longer be a contigious buffer of host memory. Instead
166 : it will compose of several fragmented regions of memory each with
167 : its own read/write privleges and size. Address translation to the
168 : input region will now have to rely on a binary search lookup of the
169 : start of the appropriate area of physical memory. It also involves
170 : doing a check against if the region can be written to. */
171 :
172 : /* FIXME: If accessing memory beyond the end of the current heap
173 : region is not allowed, sol_alloc_free will need to update the tlb
174 : arrays during program execution (this is trivial). At the same
175 : time, given sol_alloc_free is deprecated, this is unlikely to be
176 : the case. */
177 :
178 : ulong region_haddr[6];
179 : uint region_ld_sz[6];
180 : uint region_st_sz[6];
181 :
182 : /* fd_vm_input_region_t and fd_vm_acc_to_mem arrays are passed in by the bpf
183 : loaders into fd_vm_init.
184 : TODO: It might make more sense to allocate space for these in the VM. */
185 : fd_vm_input_region_t * input_mem_regions; /* An array of input mem regions represent the input region.
186 : The virtual addresses of each region are contigiuous and
187 : strictly increasing. */
188 : uint input_mem_regions_cnt;
189 : fd_vm_acc_region_meta_t * acc_region_metas; /* Represents a mapping from the instruction account indicies
190 : from the instruction context to the input memory region index
191 : of the account's data region in the input space. */
192 : uchar is_deprecated; /* The vm requires additional checks in certain CPIs if the
193 : vm's current instance was initialized by a deprecated program. */
194 :
195 : ulong reg [ FD_VM_REG_MAX ]; /* registers, indexed [0,FD_VM_REG_CNT). Note that FD_VM_REG_MAX>FD_VM_REG_CNT.
196 : As such, malformed instructions, which can have src/dst reg index in
197 : [0,FD_VM_REG_MAX), cannot access info outside reg. Aligned 8. */
198 : fd_vm_shadow_t shadow[ FD_VM_STACK_FRAME_MAX ]; /* shadow stack, indexed [0,frame_cnt), if frame_cnt>0, 0/frame_cnt-1 is
199 : bottom/top. Aligned 16. */
200 : uchar stack [ FD_VM_STACK_MAX ]; /* stack, indexed [0,FD_VM_STACK_MAX). Divided into FD_VM_STACK_FRAME_MAX
201 : frames. Each frame has a FD_VM_STACK_GUARD_SZ region followed by a
202 : FD_VM_STACK_FRAME_SZ region. reg[10] gives the offset of the start of the
203 : current stack frame. Aligned 16. */
204 : uchar heap [ FD_VM_HEAP_MAX ]; /* syscall heap, [0,heap_sz) used, [heap_sz,heap_max) free. Aligned 8. */
205 :
206 : fd_sha256_t * sha; /* Pre-joined SHA instance. This should be re-initialised before every use. */
207 :
208 : ulong magic; /* ==FD_VM_MAGIC */
209 :
210 : int direct_mapping; /* If direct mapping is enabled or not */
211 : ulong stack_frame_size; /* Size of a stack frame (varies depending on direct mapping being enabled or not) */
212 :
213 : /* Agave reports different error codes (for developers to understand the failure cause) if direct mapping is
214 : enabled AND we halt on a segfault caused by a store on an invalid vaddr. */
215 : ulong segv_store_vaddr;
216 :
217 : ulong sbpf_version; /* SBPF version, SIMD-0161 */
218 :
219 : int dump_syscall_to_pb; /* If true, syscalls will be dumped to the specified output directory */
220 : };
221 :
222 : /* FIXME: MOVE ABOVE INTO PRIVATE WHEN CONSTRUCTORS READY */
223 : /**********************************************************************/
224 :
225 : FD_PROTOTYPES_BEGIN
226 :
227 : /* FIXME: FD_VM_T NEEDS PROPER CONSTRUCTORS */
228 :
229 : /* FD_VM_{ALIGN,FOOTPRINT} describe the alignment and footprint needed
230 : for a memory region to hold a fd_vm_t. ALIGN is a positive
231 : integer power of 2. FOOTPRINT is a multiple of align.
232 : These are provided to facilitate compile time declarations. */
233 411 : #define FD_VM_ALIGN FD_VM_HOST_REGION_ALIGN
234 201 : #define FD_VM_FOOTPRINT (527824UL)
235 :
236 : /* fd_vm_{align,footprint} give the needed alignment and footprint
237 : of a memory region suitable to hold an fd_vm_t.
238 : Declaration / aligned_alloc / fd_alloca friendly (e.g. a memory
239 : region declared as "fd_vm_t _vm[1];", or created by
240 : "aligned_alloc(alignof(fd_vm_t),sizeof(fd_vm_t))" or created
241 : by "fd_alloca(alignof(fd_vm_t),sizeof(fd_vm_t))" will all
242 : automatically have the needed alignment and footprint).
243 : fd_vm_{align,footprint} return the same value as
244 : FD_VM_{ALIGN,FOOTPRINT}. */
245 : FD_FN_CONST ulong
246 : fd_vm_align( void );
247 :
248 : FD_FN_CONST ulong
249 : fd_vm_footprint( void );
250 :
251 201 : #define FD_VM_MAGIC (0xF17EDA2CEF0) /* FIREDANCE SBPF V0 */
252 :
253 : /* fd_vm_new formats memory region with suitable alignment and
254 : footprint suitable for holding a fd_vm_t. Assumes
255 : shmem points on the caller to the first byte of the memory region
256 : owned by the caller to use. Returns shmem on success and NULL on
257 : failure (logs details). The memory region will be owned by the state
258 : on successful return. The caller is not joined on return. */
259 :
260 : void *
261 : fd_vm_new( void * shmem );
262 :
263 : /* fd_vm_join joins the caller to a vm.
264 : Assumes shmem points to the first byte of the memory region holding
265 : the vm. Returns a local handle to the join on success (this is
266 : not necessarily a simple cast of the address) and NULL on failure
267 : (logs details). */
268 : fd_vm_t *
269 : fd_vm_join( void * shmem );
270 :
271 : /* fd_vm_init initializes the given fd_vm_t struct, checking that it is
272 : not null and has the correct magic value.
273 :
274 : It modifies the vm object and also returns the object for convenience.
275 :
276 : FIXME: we should split out the memory mapping setup from this function
277 : to handle those errors separately. */
278 : fd_vm_t *
279 : fd_vm_init(
280 : fd_vm_t * vm,
281 : fd_exec_instr_ctx_t *instr_ctx,
282 : ulong heap_max,
283 : ulong entry_cu,
284 : uchar const * rodata,
285 : ulong rodata_sz,
286 : ulong const * text,
287 : ulong text_cnt,
288 : ulong text_off,
289 : ulong text_sz,
290 : ulong entry_pc,
291 : ulong * calldests,
292 : ulong sbpf_version,
293 : fd_sbpf_syscalls_t * syscalls,
294 : fd_vm_trace_t * trace,
295 : fd_sha256_t * sha,
296 : fd_vm_input_region_t * mem_regions,
297 : uint mem_regions_cnt,
298 : fd_vm_acc_region_meta_t * acc_region_metas,
299 : uchar is_deprecated,
300 : int direct_mapping,
301 : int dump_syscall_to_pb );
302 :
303 : /* fd_vm_leave leaves the caller's current local join to a vm.
304 : Returns a pointer to the memory region holding the vm on success
305 : (this is not necessarily a simple cast of the
306 : address) and NULL on failure (logs details). The caller is not
307 : joined on successful return. */
308 : void *
309 : fd_vm_leave( fd_vm_t * vm );
310 :
311 : /* fd_vm_delete unformats a memory region that holds a vm.
312 : Assumes shmem points on the caller to the first
313 : byte of the memory region holding the state and that nobody is
314 : joined. Returns a pointer to the memory region on success and NULL
315 : on failure (logs details). The caller has ownership of the memory
316 : region on successful return. */
317 : void *
318 : fd_vm_delete( void * shmem );
319 :
320 : /* fd_vm_validate validates the sBPF program in the given vm. Returns
321 : success or an error code. Called before executing a sBPF program.
322 : FIXME: DOCUMENT BETTER */
323 :
324 : FD_FN_PURE int
325 : fd_vm_validate( fd_vm_t const * vm );
326 :
327 : /* fd_vm_is_check_align_enabled returns 1 if the vm should check alignment
328 : when doing memory translation. */
329 : FD_FN_PURE static inline int
330 246 : fd_vm_is_check_align_enabled( fd_vm_t const * vm ) {
331 246 : return !vm->is_deprecated;
332 246 : }
333 :
334 : /* fd_vm_is_check_size_enabled returns 1 if the vm should check size
335 : when doing memory translation. */
336 : FD_FN_PURE static inline int
337 0 : fd_vm_is_check_size_enabled( fd_vm_t const * vm ) {
338 0 : return !vm->is_deprecated;
339 0 : }
340 :
341 : /* FIXME: make this trace-aware, and move into fd_vm_init
342 : This is a temporary hack to make the fuzz harness work. */
343 : int
344 : fd_vm_setup_state_for_execution( fd_vm_t * vm ) ;
345 :
346 : /* fd_vm_exec runs vm from program start to program halt or program
347 : fault, appending an execution trace if vm is attached to a trace.
348 :
349 : Since this is running from program start, this will init r1 and r10,
350 : pop all stack frames and free all heap allocations.
351 :
352 : IMPORTANT SAFETY TIP! This currently does not zero out any other
353 : registers, the user stack region or the user heap. (FIXME: SHOULD
354 : IT??)
355 :
356 : Returns FD_VM_SUCCESS (0) on success and an FD_VM_ERR code (negative)
357 : on failure. Reasons for failure include:
358 :
359 : INVAL - NULL vm (or, for fd_vm_exec_trace, the vm is not
360 : attached to trace). FIXME: ADD OTHER INPUT ARG CHECKS?
361 :
362 : SIGTEXT - A jump/call set the program counter outside the text
363 : region or the program counter incremented beyond the
364 : text region. pc will be at the out of bounds location.
365 : ic and cu will not include the out of bounds location.
366 : For a call, the call stack frame was allocated.
367 :
368 : SIGSPLIT - A jump/call set the program counter into the middle of
369 : a multiword instruction or a multiword instruction went
370 : past the text region end. pc will be at the split. ic
371 : and cu will not include the split. For a call, the
372 : call stack frame was allocated.
373 :
374 : SIGCALL - A call set the program counter to a non-function
375 : location. pc will be at the non-function location. ic
376 : and cu will include the call but not include the
377 : non-function location. The call stack frame was
378 : allocated.
379 :
380 : SIGSTACK - The call depth limit was exceeded. pc will be at the
381 : call. ic and cu will include the call but not the call
382 : target. The call stack frame was not allocated.
383 :
384 : SIGILL - An invalid instruction was encountered (including an
385 : invalid opcode and an endian swap with an invalid bit
386 : width). pc will be at the invalid instruction. ic and
387 : cu will not include the invalid instruction.
388 :
389 : SIGSEGV - An invalid memory access (outside the program memory
390 : map) was encountered. pc will be at the faulting
391 : instruction. ic and cu will not include the faulting
392 : instruction.
393 :
394 : SIGBUS - An unaligned memory access was encountered. pc will be
395 : at the faulting instruction. ic and cu will not
396 : include the faulting instruction. (Note: currently
397 : mapped to SIGSEGV and then only if check_align is
398 : enabled.)
399 :
400 : SIGRDONLY - A write to read-only memory address was encountered.
401 : pc will be at the faulting instruction. ic and cu will
402 : not include the faulting instruction. (Note: currently
403 : mapped to SIGSEGV.)
404 :
405 : SIGCOST - The compute limit was exceeded. pc will be at the
406 : first non-executed instruction (if pc is a syscall, the
407 : syscall might have been partially executed when it ran
408 : out of budget .. see safety tip below). ic will cover
409 : all executed instructions. cu will be zero.
410 :
411 : This will considers any error returned by a syscall as a fault and
412 : returns the syscall error code here. See syscall documentation for
413 : details here. When a syscall faults, pc will be at the syscall, ic
414 : will include the syscall and cu will include the syscall and any
415 : additional costs the syscall might have incurred up to that point of
416 : the fault.
417 :
418 : IMPORTANT SAFETY TIP! Ideally, a syscall should only modify vm's
419 : state when it knows its overall syscall will be successful.
420 : Unfortunately, this is often not practical (e.g. a syscall starts
421 : processing a list of user provided commands and discovers an error
422 : condition late in the command list that did not exist at syscall
423 : start because the error condition was created by successfully
424 : executed commands earlier in the list). As such, vm's state on a
425 : faulting syscall may not be clean.
426 :
427 : FIXME: SINCE MOST SYSCALLS CAN BE IMPLEMENTED TO HAVE CLEAN FAULTING
428 : BEHAVIOR, PROVIDE A MECHANISM SO USERS CAN EASILY DETECT UNCLEAN
429 : SYSCALL FAULTS?
430 :
431 : For SIGCOST, note that the vm can speculate ahead when processing
432 : instructions. This makes it is possible to have a situation where
433 : a vm faults with, for example, SIGSEGV from a speculatively
434 : executed memory access while a non-speculative execution would have
435 : faulted with SIGCOST on an earlier instruction. In these situations,
436 : pc will be at the faulting speculatively executed instruction, ic
437 : will include all the speculatively executed instructions, cu will be
438 : zero and vm's state will include the impact of all the speculation.
439 :
440 : IMPORTANT SAFETY TIP! While different vm implementations can
441 : disagree on why a program faulted (e.g. SIGCOST versus SIGSEGV in the
442 : example above), they cannot disagree on whether or not a program
443 : faulted. As a result, the specific fault reason must never be
444 : allowed to be part of consensus.
445 :
446 : fd_vm_exec_trace runs with tracing and requires vm to be attached to
447 : a trace. fd_vm_exec_notrace runs without without tracing even if vm
448 : is attached to a trace. */
449 :
450 : int
451 : fd_vm_exec_trace( fd_vm_t * vm );
452 :
453 : int
454 : fd_vm_exec_notrace( fd_vm_t * vm );
455 :
456 : static inline int
457 186 : fd_vm_exec( fd_vm_t * vm ) {
458 186 : if( FD_UNLIKELY( vm->trace ) ) return fd_vm_exec_trace ( vm );
459 186 : else return fd_vm_exec_notrace( vm );
460 186 : }
461 :
462 : FD_PROTOTYPES_END
463 :
464 : #endif /* HEADER_fd_src_flamenco_vm_fd_vm_h */
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