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-rw-r--r--test/test_exec.cc447
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diff --git a/test/test_exec.cc b/test/test_exec.cc
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-/* SPDX-License-Identifier: GPL-2.0-or-later */
-/* Copyright (C) 2026 Richard Qin */
-
-/*
- * test_exec.cc — Self-tests for execve / ELF loader
- *
- * Tests the ELF validation, binary loading, and user stack construction
- * by creating synthetic ELF binaries in RamFS and invoking do_execve
- * in a controlled environment.
- *
- * We cannot test the actual user-space transition (that requires
- * sret to U-mode), but we CAN test everything up to and including
- * the trapframe setup.
- */
-
-#include <lume/selftest.h>
-#include <lume/elf.h>
-#include <lume/task.h>
-#include <lume/vmm.h>
-#include <lume/pmm.h>
-#include <lume/addr.h>
-#include <lume/errno.h>
-#include <lume/fdtable.h>
-#include <lume/fs.h>
-#include <lume/fs_struct.h>
-#include <lume/dcache.h>
-#include <lume/namei.h>
-#include <lume/file.h>
-#include <lume/mm_layout.h>
-#include <arch/trapframe.h>
-#include <arch/pmap.h>
-
-/* Extern: do_execve (kernel/exec.cc) */
-int do_execve(const char* pathname, const char* const* argv,
- const char* const* envp);
-
-/* Extern: VFS file creation syscalls */
-int64 sys_openat(uint64, uint64, uint64, uint64, uint64, uint64);
-int64 sys_write(uint64, uint64, uint64, uint64, uint64, uint64);
-int64 sys_close(uint64, uint64, uint64, uint64, uint64, uint64);
-
-/* ================================================================== */
-/* Helper: build a minimal valid RISC-V ELF64 in a buffer */
-/* ================================================================== */
-
-struct TestElf {
- Elf64_Ehdr ehdr;
- Elf64_Phdr phdr;
- uint8 code[16]; /* Tiny "program" — just a few NOPs */
-};
-
-/*
- * Build a minimal static ELF64 for RISC-V.
- * Single PT_LOAD segment mapping the tiny code at 0x10000.
- * Entry point = 0x10000 + offsetof(code).
- */
-static void build_minimal_elf(TestElf* elf)
-{
- /* Zero everything */
- for (uint64 i = 0; i < sizeof(*elf); i++)
- reinterpret_cast<uint8*>(elf)[i] = 0;
-
- /* ELF header */
- Elf64_Ehdr* e = &elf->ehdr;
- e->e_ident[EI_MAG0] = ELFMAG0;
- e->e_ident[EI_MAG1] = ELFMAG1;
- e->e_ident[EI_MAG2] = ELFMAG2;
- e->e_ident[EI_MAG3] = ELFMAG3;
- e->e_ident[EI_CLASS] = ELFCLASS64;
- e->e_ident[EI_DATA] = ELFDATA2LSB;
- e->e_ident[EI_VERSION] = 1;
- e->e_type = ET_EXEC;
- e->e_machine = EM_RISCV;
- e->e_version = 1;
- e->e_phoff = sizeof(Elf64_Ehdr);
- e->e_phentsize = sizeof(Elf64_Phdr);
- e->e_phnum = 1;
- e->e_ehsize = sizeof(Elf64_Ehdr);
-
- /* Code section offset within the file */
- uint64 code_offset = sizeof(Elf64_Ehdr) + sizeof(Elf64_Phdr);
-
- /* Entry point = vaddr of code */
- uint64 load_vaddr = 0x10000;
- e->e_entry = load_vaddr + code_offset;
-
- /* Program header — single PT_LOAD covering entire file */
- Elf64_Phdr* p = &elf->phdr;
- p->p_type = PT_LOAD;
- p->p_flags = PF_R | PF_X;
- p->p_offset = 0;
- p->p_vaddr = load_vaddr;
- p->p_paddr = load_vaddr;
- p->p_filesz = sizeof(TestElf);
- p->p_memsz = sizeof(TestElf);
- p->p_align = 0x1000;
-
- /* Code: RISC-V "unimp" (all zeros = illegal instruction, but good enough for testing) */
- /* We just need the loader to succeed; we won't actually execute this. */
- elf->code[0] = 0x13; /* nop = addi x0, x0, 0 */
- elf->code[4] = 0x13;
- elf->code[8] = 0x73; /* ebreak */
-}
-
-/* ================================================================== */
-/* Helper: write a buffer to a file in RamFS */
-/* ================================================================== */
-
-static int create_test_file(const char* path, const void* data, uint64 size)
-{
- /* Open with O_CREAT | O_WRONLY | O_TRUNC */
- int64 fd = sys_openat(
- static_cast<uint64>(-100), /* AT_FDCWD */
- reinterpret_cast<uint64>(path),
- O_CREAT | O_WRONLY | O_TRUNC,
- 0755, 0, 0);
- if (fd < 0) return static_cast<int>(fd);
-
- int64 written = sys_write(
- static_cast<uint64>(fd),
- reinterpret_cast<uint64>(data),
- size, 0, 0, 0);
-
- sys_close(static_cast<uint64>(fd), 0, 0, 0, 0, 0);
-
- if (written < 0) return static_cast<int>(written);
- if (static_cast<uint64>(written) != size) return -EIO;
- return 0;
-}
-
-/* ================================================================== */
-/* Helper: ensure current task has VFS context for file ops */
-/* ================================================================== */
-
-struct ExecTestCtx {
- TaskControlBlock* curr;
- VmSpace* old_mm;
- arch::TrapFrame fake_tf;
- arch::TrapFrame* old_tf;
- uint64 saved_satp;
-};
-
-static void exec_test_setup(ExecTestCtx* ctx)
-{
- ctx->curr = current_task();
-
- /* Save kernel SATP so we can restore it in teardown */
- asm volatile("csrr %0, satp" : "=r"(ctx->saved_satp));
-
- /* Save and replace mm with a fresh one */
- ctx->old_mm = ctx->curr->mm;
- ctx->curr->mm = VmSpace::create();
-
- /* Set up a fake trapframe so do_execve can modify it */
- for (uint64 i = 0; i < sizeof(ctx->fake_tf); i++)
- reinterpret_cast<uint8*>(&ctx->fake_tf)[i] = 0;
- ctx->old_tf = ctx->curr->trapframe;
- ctx->curr->trapframe = &ctx->fake_tf;
-}
-
-static void exec_test_teardown(ExecTestCtx* ctx)
-{
- /* Restore trapframe */
- ctx->curr->trapframe = ctx->old_tf;
-
- /* Destroy the test mm (may have been replaced by do_execve) */
- VmSpace* test_mm = ctx->curr->mm;
- ctx->curr->mm = ctx->old_mm;
- if (test_mm && test_mm != ctx->old_mm) {
- /* If do_execve succeeded, it activated new_mm's page table.
- * Switch back to the kernel page table before destroying. */
- asm volatile("csrw satp, %0" :: "r"(ctx->saved_satp));
- asm volatile("sfence.vma");
- test_mm->put();
- }
-}
-
-/* ================================================================== */
-/* Test cases */
-/* ================================================================== */
-
-void selftest_exec()
-{
- /* ---- 1a. Non-existent path under missing directory ---- */
- st_begin("exec: missing path returns error");
- {
- const char* argv[] = { "/no_such_dir/no_file", nullptr };
- const char* envp[] = { nullptr };
- int ret = do_execve("/no_such_dir/no_file", argv, envp);
- ST_ASSERT(ret < 0); /* -ENOENT from filename_lookup */
- }
- st_pass();
-
- /* ---- 1b. Directory is not executable ---- */
- st_begin("exec: directory returns -EACCES");
- {
- /* "/" exists and is a directory */
- const char* argv[] = { "/dev", nullptr };
- const char* envp[] = { nullptr };
- int ret = do_execve("/dev", argv, envp);
- ST_ASSERT_EQ(ret, -EACCES);
- }
- st_pass();
-
- /* ---- 2. Bad ELF magic ---- */
- st_begin("exec: bad ELF magic returns -ENOEXEC");
- {
- uint8 garbage[128];
- for (int i = 0; i < 128; i++) garbage[i] = 0xAA;
- int err = create_test_file("/test_bad_magic", garbage, 128);
- ST_ASSERT_EQ(err, 0);
-
- ExecTestCtx ctx;
- exec_test_setup(&ctx);
-
- const char* argv[] = { "/test_bad_magic", nullptr };
- const char* envp[] = { nullptr };
- int ret = do_execve("/test_bad_magic", argv, envp);
- ST_ASSERT_EQ(ret, -ENOEXEC);
-
- exec_test_teardown(&ctx);
- }
- st_pass();
-
- /* ---- 3. Wrong ELF class (32-bit) ---- */
- st_begin("exec: 32-bit ELF returns -ENOEXEC");
- {
- TestElf elf;
- build_minimal_elf(&elf);
- elf.ehdr.e_ident[EI_CLASS] = 1; /* ELFCLASS32 */
- int err = create_test_file("/test_elf32", &elf, sizeof(elf));
- ST_ASSERT_EQ(err, 0);
-
- ExecTestCtx ctx;
- exec_test_setup(&ctx);
-
- const char* argv[] = { "/test_elf32", nullptr };
- const char* envp[] = { nullptr };
- int ret = do_execve("/test_elf32", argv, envp);
- ST_ASSERT_EQ(ret, -ENOEXEC);
-
- exec_test_teardown(&ctx);
- }
- st_pass();
-
- /* ---- 4. Wrong endianness (big-endian) ---- */
- st_begin("exec: big-endian ELF returns -ENOEXEC");
- {
- TestElf elf;
- build_minimal_elf(&elf);
- elf.ehdr.e_ident[EI_DATA] = 2; /* ELFDATA2MSB */
- int err = create_test_file("/test_be", &elf, sizeof(elf));
- ST_ASSERT_EQ(err, 0);
-
- ExecTestCtx ctx;
- exec_test_setup(&ctx);
-
- const char* argv[] = { "/test_be", nullptr };
- const char* envp[] = { nullptr };
- int ret = do_execve("/test_be", argv, envp);
- ST_ASSERT_EQ(ret, -ENOEXEC);
-
- exec_test_teardown(&ctx);
- }
- st_pass();
-
- /* ---- 5. Wrong machine (x86_64 instead of RISC-V) ---- */
- st_begin("exec: wrong machine type returns -ENOEXEC");
- {
- TestElf elf;
- build_minimal_elf(&elf);
- elf.ehdr.e_machine = 62; /* EM_X86_64 */
- int err = create_test_file("/test_x86", &elf, sizeof(elf));
- ST_ASSERT_EQ(err, 0);
-
- ExecTestCtx ctx;
- exec_test_setup(&ctx);
-
- const char* argv[] = { "/test_x86", nullptr };
- const char* envp[] = { nullptr };
- int ret = do_execve("/test_x86", argv, envp);
- ST_ASSERT_EQ(ret, -ENOEXEC);
-
- exec_test_teardown(&ctx);
- }
- st_pass();
-
- /* ---- 6. Truncated ELF (too small for header) ---- */
- st_begin("exec: truncated ELF returns -ENOEXEC");
- {
- /* Valid magic but file is too short for full header */
- uint8 tiny[8] = { 0x7f, 'E', 'L', 'F', 2, 1, 1, 0 };
- int err = create_test_file("/test_tiny", tiny, sizeof(tiny));
- ST_ASSERT_EQ(err, 0);
-
- ExecTestCtx ctx;
- exec_test_setup(&ctx);
-
- const char* argv[] = { "/test_tiny", nullptr };
- const char* envp[] = { nullptr };
- int ret = do_execve("/test_tiny", argv, envp);
- ST_ASSERT_EQ(ret, -ENOEXEC);
-
- exec_test_teardown(&ctx);
- }
- st_pass();
-
- /* ---- 7. Zero program headers ---- */
- st_begin("exec: zero phnum returns -ENOEXEC");
- {
- TestElf elf;
- build_minimal_elf(&elf);
- elf.ehdr.e_phnum = 0;
- int err = create_test_file("/test_nophdr", &elf, sizeof(elf));
- ST_ASSERT_EQ(err, 0);
-
- ExecTestCtx ctx;
- exec_test_setup(&ctx);
-
- const char* argv[] = { "/test_nophdr", nullptr };
- const char* envp[] = { nullptr };
- int ret = do_execve("/test_nophdr", argv, envp);
- ST_ASSERT_EQ(ret, -ENOEXEC);
-
- exec_test_teardown(&ctx);
- }
- st_pass();
-
- /* ---- 8. Valid ELF: successful load and trapframe setup ---- */
- st_begin("exec: valid ELF loads and sets up trapframe");
- {
- TestElf elf;
- build_minimal_elf(&elf);
- int err = create_test_file("/test_valid", &elf, sizeof(elf));
- ST_ASSERT_EQ(err, 0);
-
- ExecTestCtx ctx;
- exec_test_setup(&ctx);
-
- const char* argv[] = { "/test_valid", nullptr };
- const char* envp[] = { "HOME=/", nullptr };
- int ret = do_execve("/test_valid", argv, envp);
- ST_ASSERT_EQ(ret, 0);
-
- /* Verify trapframe was set up correctly */
- arch::TrapFrame* tf = &ctx.fake_tf;
-
- /* Entry point should match what we set in the ELF */
- uint64 code_offset = sizeof(Elf64_Ehdr) + sizeof(Elf64_Phdr);
- uint64 expected_entry = 0x10000 + code_offset;
- ST_ASSERT_EQ(tf->epc, expected_entry);
-
- /* Stack pointer should be in user space, below the stack top */
- ST_ASSERT(tf->sp > 0);
- ST_ASSERT(tf->sp < kUserStackTop);
- ST_ASSERT(tf->sp >= kUserStackBase);
-
- /* sstatus: SPP=0 (U-mode), SPIE=1 (interrupts enabled on sret) */
- uint64 spp_bit = (1ULL << 8);
- uint64 spie_bit = (1ULL << 5);
- ST_ASSERT_EQ(tf->sstatus & spp_bit, 0ULL); /* Not S-mode */
- ST_ASSERT_EQ(tf->sstatus & spie_bit, spie_bit); /* SPIE set */
-
- /* General registers should be zeroed */
- ST_ASSERT_EQ(tf->ra, 0ULL);
- ST_ASSERT_EQ(tf->gp, 0ULL);
- ST_ASSERT_EQ(tf->tp, 0ULL);
- for (int i = 0; i < 7; i++)
- ST_ASSERT_EQ(tf->t[i], 0ULL);
- for (int i = 0; i < 12; i++)
- ST_ASSERT_EQ(tf->s[i], 0ULL);
- for (int i = 0; i < 8; i++)
- ST_ASSERT_EQ(tf->a[i], 0ULL);
-
- exec_test_teardown(&ctx);
- }
- st_pass();
-
- /* ---- 9. Verify user stack layout (argc/argv) ---- */
- st_begin("exec: user stack has correct argc/argv layout");
- {
- TestElf elf;
- build_minimal_elf(&elf);
- int err = create_test_file("/test_stack", &elf, sizeof(elf));
- ST_ASSERT_EQ(err, 0);
-
- ExecTestCtx ctx;
- exec_test_setup(&ctx);
-
- const char* argv[] = { "/test_stack", "arg1", nullptr };
- const char* envp[] = { "A=B", nullptr };
- int ret = do_execve("/test_stack", argv, envp);
- ST_ASSERT_EQ(ret, 0);
-
- /* The stack was set up in the new mm.
- * Read argc from the top of the stack using pmap lookup. */
- VmSpace* mm = ctx.curr->mm;
- uint64 sp = ctx.fake_tf.sp;
-
- /* Look up the physical page for sp */
- uint64 pa = 0;
- bool mapped = pmap::lookup(mm->root_pa, sp & ~(kPageSize - 1), &pa);
- ST_ASSERT(mapped);
-
- /* Read argc (first uint64 on stack) */
- uint64 page_offset = sp & (kPageSize - 1);
- uint8* kva = reinterpret_cast<uint8*>(pa_to_va(PhysAddr{pa}).raw);
- uint64 argc = *reinterpret_cast<uint64*>(kva + page_offset);
- ST_ASSERT_EQ(argc, 2ULL); /* "/test_stack" and "arg1" */
-
- exec_test_teardown(&ctx);
- }
- st_pass();
-
- /* ---- 10. Multiple consecutive execve replaces mm correctly ---- */
- st_begin("exec: consecutive execve replaces address space");
- {
- TestElf elf;
- build_minimal_elf(&elf);
- int err = create_test_file("/test_reexec", &elf, sizeof(elf));
- ST_ASSERT_EQ(err, 0);
-
- ExecTestCtx ctx;
- exec_test_setup(&ctx);
-
- /* First exec */
- const char* argv[] = { "/test_reexec", nullptr };
- const char* envp[] = { nullptr };
- int ret = do_execve("/test_reexec", argv, envp);
- ST_ASSERT_EQ(ret, 0);
-
- VmSpace* first_mm = ctx.curr->mm;
- ST_ASSERT(first_mm != nullptr);
-
- /* Second exec — should replace the first mm */
- ret = do_execve("/test_reexec", argv, envp);
- ST_ASSERT_EQ(ret, 0);
-
- /* mm should be different (new address space) */
- VmSpace* second_mm = ctx.curr->mm;
- ST_ASSERT(second_mm != nullptr);
- ST_ASSERT_NE(first_mm, second_mm);
-
- exec_test_teardown(&ctx);
- }
- st_pass();
-}
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