diff options
Diffstat (limited to 'lib/transform-dis.c')
| -rw-r--r-- | lib/transform-dis.c | 127 |
1 files changed, 121 insertions, 6 deletions
diff --git a/lib/transform-dis.c b/lib/transform-dis.c index 6fc6d7f..b8df987 100644 --- a/lib/transform-dis.c +++ b/lib/transform-dis.c @@ -1,9 +1,124 @@ #include "substitute-internal.h" #ifndef TARGET_UNSUPPORTED - #include "transform-dis.inc.h" - #ifdef TARGET_arm - #include "transform-dis-arm-multi.inc.h" - #else - #error ? - #endif + +#include "substitute.h" +#include "dis.h" +#include <stdbool.h> +#include <stdint.h> + +#define P(x) transform_dis_##x + +struct transform_dis_ctx { + /* outputs */ + bool modify; + int err; + + bool pc_low_bit; + uintptr_t pc_patch_start; + uintptr_t pc_patch_end; + uintptr_t pc; + int op_size; + unsigned op; + unsigned newop; + unsigned newval[4]; + + const void *ptr; + void **rewritten_ptr_ptr; + void *write_newop_here; + + struct arch_dis_ctx arch; +}; + +#define tdis_ctx struct transform_dis_ctx * +#define TDIS_CTX_MODIFY(ctx) ((ctx)->modify) +#define TDIS_CTX_NEWVAL(ctx, n) ((ctx)->newval[n]) +#define TDIS_CTX_SET_NEWOP(ctx, new) ((ctx)->newop = (new)) + +/* largely similar to jump_dis */ + +static INLINE UNUSED void transform_dis_ret(struct transform_dis_ctx *ctx) { + /* ret is okay if it's at the end of the patch */ + if (ctx->pc + ctx->op_size < ctx->pc_patch_end) + ctx->err = SUBSTITUTE_ERR_FUNC_TOO_SHORT; +} + +static INLINE UNUSED void transform_dis_branch(struct transform_dis_ctx *ctx, + uintptr_t dpc, UNUSED bool conditional) { + if (dpc >= ctx->pc_patch_start && dpc < ctx->pc_patch_end) { + /* don't support this for now */ + ctx->err = SUBSTITUTE_ERR_FUNC_BAD_INSN_AT_START; + } + /* branch out of bounds is fine */ +} + +static INLINE UNUSED void transform_dis_unidentified(UNUSED struct transform_dis_ctx *ctx) { + /* this isn't exhaustive, so unidentified is fine */ +} + +static INLINE UNUSED void transform_dis_bad(struct transform_dis_ctx *ctx) { + ctx->err = SUBSTITUTE_ERR_FUNC_BAD_INSN_AT_START; +} + + +static void transform_dis_dis(struct transform_dis_ctx *ctx); + +int transform_dis_main(const void *restrict code_ptr, + void **restrict rewritten_ptr_ptr, + uintptr_t pc_patch_start, + uintptr_t pc_patch_end, + bool pc_low_bit, + int *offset_by_pcdiff) { + struct transform_dis_ctx ctx; + ctx.pc_patch_start = pc_patch_start; + ctx.pc_patch_end = pc_patch_end; + ctx.pc_low_bit = pc_low_bit; + ctx.pc = pc_patch_start; + /* data is written to rewritten both by this function directly and, in case + * additional scaffolding is needed, by arch-specific transform_dis_* */ + ctx.rewritten_ptr_ptr = rewritten_ptr_ptr; + void *rewritten_start = *rewritten_ptr_ptr; + int written_pcdiff = 0; + while (ctx.pc < ctx.pc_patch_end) { + ctx.modify = false; + ctx.err = 0; + ctx.newop = ctx.op; + ctx.ptr = code_ptr + (ctx.pc - pc_patch_start); + void *rewritten_ptr = *rewritten_ptr_ptr; + ctx.write_newop_here = rewritten_ptr; + transform_dis_dis(&ctx); + + if (ctx.err) + return ctx.err; + if (ctx.write_newop_here != NULL) { + if (ctx.op_size == 4) + *(uint32_t *) ctx.write_newop_here = ctx.newop; + else if (ctx.op_size == 2) + *(uint16_t *) ctx.write_newop_here = ctx.newop; + else + __builtin_abort(); + if (*rewritten_ptr_ptr == rewritten_ptr) + *rewritten_ptr_ptr += ctx.op_size; + } + ctx.pc += ctx.op_size; + int pcdiff = ctx.pc - ctx.pc_patch_start; + while (written_pcdiff < pcdiff) + offset_by_pcdiff[written_pcdiff++] = -1; + offset_by_pcdiff[written_pcdiff++] = (int) (*rewritten_ptr_ptr - rewritten_start); + } + return SUBSTITUTE_OK; +} + +static inline void op32(struct transform_dis_ctx *ctx, uint32_t op) { + void **rpp = ctx->rewritten_ptr_ptr; + *(uint32_t *) *rpp = op; + *rpp += 4; +} + +#ifdef TARGET_arm + #include "transform-dis-arm-multi.inc.h" +#else + #include "transform-dis-arm64.inc.h" #endif +#include TARGET_DIS_HEADER + +#endif /* TARGET_UNSUPPORTED */ |