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# Example showing mmap syscall.
# Create a new segment using mmap, save the address, write to it.
#
# To run:
#   $ ./bootstrap translate init.linux apps/ex12.subx -o apps/ex12
#   $ ./bootstrap run apps/ex12
# You shouldn't get a segmentation fault.

== code
#   instruction                     effective address                                                   register    displacement    immediate
# . op          subop               mod             rm32          base        index         scale       r32
# . 1-3 bytes   3 bits              2 bits          3 bits        3 bits      3 bits        2 bits      2 bits      0/1/2/4 bytes   0/1/2/4 bytes

Entry:
    # mmap(Mmap-new-segment->len)
    bb/copy-to-ebx  Mmap-new-segment/imm32
    e8/call  syscall_mmap/disp32

    # write to *eax to check that we have access to the newly-allocated segment
    c7          0/subop/copy        0/mod/direct    0/rm32/eax    .           .             .           .           .               0x34/imm32        # copy to *eax

    # exit(eax)
    89/copy                         3/mod/direct    3/rm32/ebx    .           .             .           0/r32/eax   .               .                 # copy eax to ebx
    e8/call  syscall_exit/disp32

== data

# various constants used here were found in the Linux sources (search for file mman-common.h)
Mmap-new-segment:  # type mmap_arg_struct
    # addr
    0/imm32
    # len
    0x100/imm32
    # protection flags
    3/imm32  # PROT_READ | PROT_WRITE
    # sharing flags
    0x22/imm32  # MAP_PRIVATE | MAP_ANONYMOUS
    # fd
    -1/imm32  # since MAP_ANONYMOUS is specified
    # offset
    0/imm32  # since MAP_ANONYMOUS is specified

# . . vim:nowrap:textwidth=0
s="n">n:num [ local-scope load-ingredients n <- length *x ] +mem: storing 3 in location 1 :(before "End Instruction Inserting/Deleting Transforms") initialize_transform_rewrite_literal_string_to_text(); Transform.push_back(rewrite_literal_string_to_text); // idempotent :(before "End Globals") set<string> recipes_taking_literal_strings; :(code) void initialize_transform_rewrite_literal_string_to_text() { recipes_taking_literal_strings.insert("$print"); recipes_taking_literal_strings.insert("$dump-trace"); recipes_taking_literal_strings.insert("$system"); recipes_taking_literal_strings.insert("trace"); recipes_taking_literal_strings.insert("stash"); recipes_taking_literal_strings.insert("new"); recipes_taking_literal_strings.insert("run"); recipes_taking_literal_strings.insert("memory-should-contain"); recipes_taking_literal_strings.insert("trace-should-contain"); recipes_taking_literal_strings.insert("trace-should-not-contain"); recipes_taking_literal_strings.insert("check-trace-count-for-label"); // End initialize_transform_rewrite_literal_string_to_text() } void rewrite_literal_string_to_text(const recipe_ordinal r) { recipe& caller = get(Recipe, r); trace(9991, "transform") << "--- rewrite literal strings in recipe " << caller.name << end(); if (contains_numeric_locations(caller)) return; vector<instruction> new_instructions; for (int i = 0; i < SIZE(caller.steps); ++i) { instruction& inst = caller.steps.at(i); if (recipes_taking_literal_strings.find(inst.name) == recipes_taking_literal_strings.end()) { for (int j = 0; j < SIZE(inst.ingredients); ++j) { if (!is_literal_text(inst.ingredients.at(j))) continue; instruction def; ostringstream ingredient_name; ingredient_name << inst.name << '_' << i << '_' << j << ":text"; def.name = "new"; def.ingredients.push_back(inst.ingredients.at(j)); def.products.push_back(reagent(ingredient_name.str())); new_instructions.push_back(def); inst.ingredients.at(j).clear(); // reclaim old memory inst.ingredients.at(j) = reagent(ingredient_name.str()); } } new_instructions.push_back(inst); } caller.steps.swap(new_instructions); } bool contains_numeric_locations(const recipe& caller) { for (int i = 0; i < SIZE(caller.steps); ++i) { const instruction& inst = caller.steps.at(i); for (int in = 0; in < SIZE(inst.ingredients); ++in) if (is_numeric_location(inst.ingredients.at(in))) return true; for (int out = 0; out < SIZE(inst.products); ++out) if (is_numeric_location(inst.products.at(out))) return true; } return false; }