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linux-user: Tolerate CONFIG_LSM_MMAP_MIN_ADDR 

Running qemu-i386 on a system running with SELinux in enforcing mode
(more precisely: s390x trixie container on Fedora 40) fails with:

    qemu-i386: tests/tcg/i386-linux-user/sigreturn-sigmask: Unable to find a guest_base to satisfy all guest address mapping requirements
      00000000-ffffffff

The reason is that main() determines mmap_min_addr from
/proc/sys/vm/mmap_min_addr, but SELinux additionally defines
CONFIG_LSM_MMAP_MIN_ADDR, which is normally larger: 32K or 64K, but,
in general, can be anything. There is no portable way to query its
value: /boot/config, /proc/config and /proc/config.gz are distro- and
environment-specific.

Once the identity map fails, the magnitude of guest_base does not
matter, so fix by starting the search from 1M or 1G.

Cc: qemu-stable@nongnu.org
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2598
Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Message-ID: <20241023002558.34589-1-iii@linux.ibm.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Ilya Leoshkevich 2024-10-23 02:24:31 +02:00 committed by Richard Henderson
parent 2a339fee45
commit fb7f3572b1
1 changed files with 1 additions and 1 deletions
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2
linux-user/elfload.c
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@ -2898,7 +2898,7 @@ static uintptr_t pgb_try_itree(const PGBAddrs *ga, uintptr_t base,
static uintptr_t pgb_find_itree(const PGBAddrs *ga, IntervalTreeRoot *root,
uintptr_t align, uintptr_t brk)
{
uintptr_t last = mmap_min_addr;
uintptr_t last = sizeof(uintptr_t) == 4 ? MiB : GiB;
uintptr_t base, skip;
while (true) {