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mcount-dynamic: Use MAP_FIXED_NOREPLACE for trampoline #1798

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merged 1 commit into from Sep 4, 2023
Merged

mcount-dynamic: Use MAP_FIXED_NOREPLACE for trampoline #1798

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12 changes: 10 additions & 2 deletions arch/aarch64/mcount-dynamic.c
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Expand Up @@ -63,13 +63,21 @@ int mcount_setup_trampoline(struct mcount_dynamic_info *mdi)
mdi->trampoline -= sizeof(trampoline);

if (unlikely(mdi->trampoline < mdi->text_addr + mdi->text_size)) {
void *trampoline_check;

mdi->trampoline += sizeof(trampoline);
mdi->text_size += PAGE_SIZE;

pr_dbg("adding a page for fentry trampoline at %#lx\n", mdi->trampoline);

mmap((void *)mdi->trampoline, PAGE_SIZE, PROT_READ | PROT_WRITE | PROT_EXEC,
MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
trampoline_check = mmap((void *)mdi->trampoline, PAGE_SIZE,
PROT_READ | PROT_WRITE | PROT_EXEC,
MAP_FIXED_NOREPLACE | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);

if (trampoline_check != (void *)mdi->trampoline) {
pr_err("could not map trampoline at desired location %#lx, got %#lx: %m\n",
mdi->trampoline, (uintptr_t)trampoline_check);
}
}

page_offset = mdi->text_addr & (PAGE_SIZE - 1);
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8 changes: 5 additions & 3 deletions arch/i386/mcount-dynamic.c
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Expand Up @@ -30,10 +30,12 @@ int mcount_setup_trampoline(struct mcount_dynamic_info *mdi)
pr_dbg2("adding a page for fentry trampoline at %#lx\n", mdi->trampoline);

trampoline_check = mmap((void *)mdi->trampoline, PAGE_SIZE, PROT_READ | PROT_WRITE,
MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
MAP_FIXED_NOREPLACE | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);

if (trampoline_check == MAP_FAILED)
pr_err("failed to mmap trampoline for setup");
if (trampoline_check != (void *)mdi->trampoline) {
pr_err("could not map trampoline at desired location %#lx, got %#lx: %m\n",
mdi->trampoline, (uintptr_t)trampoline_check);
}
}

if (mprotect((void *)mdi->text_addr, mdi->text_size, PROT_READ | PROT_WRITE)) {
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8 changes: 5 additions & 3 deletions arch/x86_64/mcount-dynamic.c
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Expand Up @@ -43,10 +43,12 @@ int mcount_setup_trampoline(struct mcount_dynamic_info *mdi)

trampoline_check = mmap((void *)mdi->trampoline, PAGE_SIZE,
PROT_READ | PROT_WRITE | PROT_EXEC,
MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
MAP_FIXED_NOREPLACE | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);

if (trampoline_check == MAP_FAILED)
pr_err("failed to mmap trampoline for setup");
if (trampoline_check != (void *)mdi->trampoline) {
pr_err("could not map trampoline at desired location %#lx, got %#lx: %m\n",
mdi->trampoline, (uintptr_t)trampoline_check);
}
}

if (mprotect(PAGE_ADDR(mdi->text_addr), PAGE_LEN(mdi->text_addr, mdi->text_size),
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