On Sat, Aug 19, 2023 at 3:49 AM Karim Taha <kariem.taha...@gmail.com> wrote:
> From: Stacey Son <s...@freebsd.org>
>
> Co-authored-by: Mikaël Urankar <mikael.uran...@gmail.com>
>
> Signed-off-by: Mikaël Urankar <mikael.uran...@gmail.com>
> Signed-off-by: Stacey Son <s...@freebsd.org>
> Signed-off-by: Karim Taha <kariem.taha...@gmail.com>
> ---
> bsd-user/bsd-mem.h | 85 +++++++++++++++++++++++++++++++++++
> bsd-user/freebsd/os-syscall.c | 7 +++
> 2 files changed, 92 insertions(+)
>
emacs works with this, iirc, and it's super picky about brk being
pedantically correct.
This also doesn't match current linux-user. Perhaps the caution it uses is
no longer
needed? I think it's another area we should invite the linux-user
maintainers to
comment.
Warner
> diff --git a/bsd-user/bsd-mem.h b/bsd-user/bsd-mem.h
> index edbccd3111..6f33148eb7 100644
> --- a/bsd-user/bsd-mem.h
> +++ b/bsd-user/bsd-mem.h
> @@ -167,4 +167,89 @@ static inline abi_long do_bsd_mincore(abi_ulong
> target_addr, abi_ulong len,
> return ret;
> }
>
> +#ifdef DO_DEBUG
> +#define DEBUGF_BRK(message, args...) \
> + do { fprintf(stderr, (message), ## args); } while (0)
> +#else
> +#define DEBUGF_BRK(message, args...)
> +#endif
> +
> +/* do_brk() must return target values and target errnos. */
> +static inline abi_long do_obreak(abi_ulong new_brk)
> +{
> + abi_long mapped_addr;
> + int new_alloc_size;
> +
> + DEBUGF_BRK("do_brk(" TARGET_ABI_FMT_lx ") -> ", new_brk);
> +
> + if (!new_brk) {
> + DEBUGF_BRK(TARGET_ABI_FMT_lx " (!new_brk)\n", bsd_target_brk);
> + return bsd_target_brk;
> + }
> + if (new_brk < bsd_target_original_brk) {
> + DEBUGF_BRK(TARGET_ABI_FMT_lx " (new_brk <
> bsd_target_original_brk)\n",
> + bsd_target_brk);
> + return bsd_target_brk;
> + }
> +
> + /*
> + * If the new brk is less than the highest page reserved to the
> target heap
> + * allocation, set it and we're almost done...
> + */
> + if (new_brk <= brk_page) {
> + /*
> + * Heap contents are initialized to zero, as for anonymous mapped
> pages.
> + */
> + if (new_brk > bsd_target_brk) {
> + memset(g2h_untagged(bsd_target_brk), 0, new_brk -
> bsd_target_brk);
> + }
> + bsd_target_brk = new_brk;
> + DEBUGF_BRK(TARGET_ABI_FMT_lx " (new_brk <= brk_page)\n",
> + bsd_target_brk);
> + return bsd_target_brk;
> + }
> +
> + /*
> + * We need to allocate more memory after the brk... Note that we
> don't use
> + * MAP_FIXED because that will map over the top of any existing
> mapping
> + * (like the one with the host libc or qemu itself); instead we treat
> + * "mapped but at wrong address" as a failure and unmap again.
> + */
> + new_alloc_size = HOST_PAGE_ALIGN(new_brk - brk_page);
> + mapped_addr = get_errno(target_mmap(brk_page, new_alloc_size,
> + PROT_READ | PROT_WRITE,
> + MAP_ANON | MAP_PRIVATE, -1, 0));
> +
> + if (mapped_addr == brk_page) {
> + /*
> + * Heap contents are initialized to zero, as for anonymous mapped
> pages.
> + * Technically the new pages are already initialized to zero
> since they
> + * *are* anonymous mapped pages, however we have to take care
> with the
> + * contents that come from the remaining part of the previous
> page: it
> + * may contains garbage data due to a previous heap usage (grown
> then
> + * shrunken).
> + */
> + memset(g2h_untagged(bsd_target_brk), 0, brk_page -
> bsd_target_brk);
> +
> + bsd_target_brk = new_brk;
> + brk_page = HOST_PAGE_ALIGN(bsd_target_brk);
> + DEBUGF_BRK(TARGET_ABI_FMT_lx " (mapped_addr == brk_page)\n",
> + bsd_target_brk);
> + return bsd_target_brk;
> + } else if (mapped_addr != -1) {
> + /*
> + * Mapped but at wrong address, meaning there wasn't actually
> enough
> + * space for this brk.
> + */
> + target_munmap(mapped_addr, new_alloc_size);
> + mapped_addr = -1;
> + DEBUGF_BRK(TARGET_ABI_FMT_lx " (mapped_addr != -1)\n",
> bsd_target_brk);
> + } else {
> + DEBUGF_BRK(TARGET_ABI_FMT_lx " (otherwise)\n", bsd_target_brk);
> + }
> +
> + /* For everything else, return the previous break. */
> + return bsd_target_brk;
> +}
> +
> #endif /* BSD_USER_BSD_MEM_H */
> diff --git a/bsd-user/freebsd/os-syscall.c b/bsd-user/freebsd/os-syscall.c
> index 1db0907504..1b9dca9164 100644
> --- a/bsd-user/freebsd/os-syscall.c
> +++ b/bsd-user/freebsd/os-syscall.c
> @@ -543,6 +543,13 @@ 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}
> */
> --
> 2.40.0
>
>
