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linux-user: Adjust task_unmapped_base for reserved_va 

Ensure that the chosen values for mmap_next_start and
task_unmapped_base are within the guest address space.

Tested-by: Helge Deller <deller@gmx.de>
Reviewed-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2023-08-02 14:25:27 -07:00
parent 0450cf0897
commit c8fb5cf97d
3 changed files with 64 additions and 16 deletions
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28
linux-user/main.c
View File

@ -821,6 +821,34 @@ int main(int argc, char **argv, char **envp)
reserved_va = max_reserved_va;
}
/*
* Temporarily disable
* "comparison is always false due to limited range of data type"
* due to comparison between (possible) uint64_t and uintptr_t.
*/
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wtype-limits"
/*
* Select an initial value for task_unmapped_base that is in range.
*/
if (reserved_va) {
if (TASK_UNMAPPED_BASE < reserved_va) {
task_unmapped_base = TASK_UNMAPPED_BASE;
} else {
/* The most common default formula is TASK_SIZE / 3. */
task_unmapped_base = TARGET_PAGE_ALIGN(reserved_va / 3);
}
} else if (TASK_UNMAPPED_BASE < UINTPTR_MAX) {
task_unmapped_base = TASK_UNMAPPED_BASE;
} else {
/* 32-bit host: pick something medium size. */
task_unmapped_base = 0x10000000;
}
mmap_next_start = task_unmapped_base;
#pragma GCC diagnostic pop
{
Error *err = NULL;
if (seed_optarg != NULL) {

18
linux-user/mmap.c
View File

@ -299,20 +299,8 @@ static bool mmap_frag(abi_ulong real_start, abi_ulong start, abi_ulong last,
return true;
}
#if HOST_LONG_BITS == 64 && TARGET_ABI_BITS == 64
#ifdef TARGET_AARCH64
# define TASK_UNMAPPED_BASE 0x5500000000
#else
# define TASK_UNMAPPED_BASE (1ul << 38)
#endif
#else
#ifdef TARGET_HPPA
# define TASK_UNMAPPED_BASE 0xfa000000
#else
# define TASK_UNMAPPED_BASE 0x40000000
#endif
#endif
abi_ulong mmap_next_start = TASK_UNMAPPED_BASE;
abi_ulong task_unmapped_base;
abi_ulong mmap_next_start;
/*
* Subroutine of mmap_find_vma, used when we have pre-allocated
@ -391,7 +379,7 @@ abi_ulong mmap_find_vma(abi_ulong start, abi_ulong size, abi_ulong align)
if ((addr & (align - 1)) == 0) {
/* Success. */
if (start == mmap_next_start && addr >= TASK_UNMAPPED_BASE) {
if (start == mmap_next_start && addr >= task_unmapped_base) {
mmap_next_start = addr + size;
}
return addr;

34
linux-user/user-mmap.h
View File

@ -18,6 +18,39 @@
#ifndef LINUX_USER_USER_MMAP_H
#define LINUX_USER_USER_MMAP_H
#if HOST_LONG_BITS == 64 && TARGET_ABI_BITS == 64
#ifdef TARGET_AARCH64
# define TASK_UNMAPPED_BASE 0x5500000000
#else
# define TASK_UNMAPPED_BASE (1ul << 38)
#endif
#else
#ifdef TARGET_HPPA
# define TASK_UNMAPPED_BASE 0xfa000000
#else
# define TASK_UNMAPPED_BASE 0x40000000
#endif
#endif
/*
* Guest parameters for the ADDR_COMPAT_LAYOUT personality
* (at present this is the only layout supported by QEMU).
*
* TASK_UNMAPPED_BASE: For mmap without hint (addr != 0), the search
* for unused virtual memory begins at TASK_UNMAPPED_BASE.
*
* task_unmapped_base: When the guest address space is limited via -R,
* the value of TASK_UNMAPPED_BASE is adjusted to fit.
*/
extern abi_ulong task_unmapped_base;
/*
* mmap_next_start: The base address for the next mmap without hint,
* increased after each successful map, starting at task_unmapped_base.
* This is an optimization within QEMU and not part of ADDR_COMPAT_LAYOUT.
*/
extern abi_ulong mmap_next_start;
int target_mprotect(abi_ulong start, abi_ulong len, int prot);
abi_long target_mmap(abi_ulong start, abi_ulong len, int prot,
int flags, int fd, off_t offset);
@ -26,7 +59,6 @@ abi_long target_mremap(abi_ulong old_addr, abi_ulong old_size,
abi_ulong new_size, unsigned long flags,
abi_ulong new_addr);
abi_long target_madvise(abi_ulong start, abi_ulong len_in, int advice);
extern abi_ulong mmap_next_start;
abi_ulong mmap_find_vma(abi_ulong, abi_ulong, abi_ulong);
void mmap_fork_start(void);
void mmap_fork_end(int child);