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bsd-user: Implement do_obreak function

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Match linux-user, by manually applying the following commits, in order:

d28b3c90cf   linux-user: Make sure initial brk(0) is page-aligned
15ad98536a   linux-user: Fix qemu brk() to not zero bytes on current page
dfe49864af   linux-user: Prohibit brk() to to shrink below initial heap address
eac78a4b0b   linux-user: Fix signed math overflow in brk() syscall
c6cc059eca   linux-user: Do not call get_errno() in do_brk()
e69e032d1a   linux-user: Use MAP_FIXED_NOREPLACE for do_brk()
cb9d5d1fda   linux-user: Do nothing if too small brk is specified
2aea137a42   linux-user: Do not align brk with host page size

Signed-off-by: Stacey Son <sson@FreeBSD.org>
Signed-off-by: Karim Taha <kariem.taha2.7@gmail.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230925182709.4834-19-kariem.taha2.7@gmail.com>
This commit is contained in:
Stacey Son 2023-09-25 21:27:04 +03:00 committed by Warner Losh
parent 83b045ad4e
commit a99d740347
2 changed files with 52 additions and 0 deletions
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45
bsd-user/bsd-mem.h
View File

@ -212,4 +212,49 @@ static inline abi_long do_bsd_mincore(abi_ulong target_addr, abi_ulong len,
return ret;
}
/* do_brk() must return target values and target errnos. */
static inline abi_long do_obreak(abi_ulong brk_val)
{
abi_long mapped_addr;
abi_ulong new_brk;
abi_ulong old_brk;
/* brk pointers are always untagged */
/* do not allow to shrink below initial brk value */
if (brk_val < initial_target_brk) {
return target_brk;
}
new_brk = TARGET_PAGE_ALIGN(brk_val);
old_brk = TARGET_PAGE_ALIGN(target_brk);
/* new and old target_brk might be on the same page */
if (new_brk == old_brk) {
target_brk = brk_val;
return target_brk;
}
/* Release heap if necesary */
if (new_brk < old_brk) {
target_munmap(new_brk, old_brk - new_brk);
target_brk = brk_val;
return target_brk;
}
mapped_addr = target_mmap(old_brk, new_brk - old_brk,
PROT_READ | PROT_WRITE,
MAP_FIXED | MAP_EXCL | MAP_ANON | MAP_PRIVATE,
-1, 0);
if (mapped_addr == old_brk) {
target_brk = brk_val;
return target_brk;
}
/* For everything else, return the previous break. */
return target_brk;
}
#endif /* BSD_USER_BSD_MEM_H */

7
bsd-user/freebsd/os-syscall.c
View File

@ -855,6 +855,13 @@ static abi_long freebsd_syscall(void *cpu_env, int num, abi_long arg1,
break;
#endif
/*
* Misc
*/
case TARGET_FREEBSD_NR_break:
ret = do_obreak(arg1);
break;
/*
* sys{ctl, arch, call}
*/