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[PULL 1/9] linux-user: Set CF_PARALLEL when mapping shared memory
From: |
Laurent Vivier |
Subject: |
[PULL 1/9] linux-user: Set CF_PARALLEL when mapping shared memory |
Date: |
Mon, 21 Jun 2021 13:04:37 +0200 |
From: Richard Henderson <richard.henderson@linaro.org>
Signal the translator to use host atomic instructions for
guest operations, insofar as it is possible. This is the
best we can do to allow the guest to interact atomically
with other processes.
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/121
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20210612060828.695332-1-richard.henderson@linaro.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
---
linux-user/mmap.c | 14 ++++++++++++++
linux-user/syscall.c | 12 ++++++++++++
2 files changed, 26 insertions(+)
diff --git a/linux-user/mmap.c b/linux-user/mmap.c
index 7e3b2450368a..0e103859fed8 100644
--- a/linux-user/mmap.c
+++ b/linux-user/mmap.c
@@ -451,6 +451,20 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, int
target_prot,
goto fail;
}
+ /*
+ * If we're mapping shared memory, ensure we generate code for parallel
+ * execution and flush old translations. This will work up to the level
+ * supported by the host -- anything that requires EXCP_ATOMIC will not
+ * be atomic with respect to an external process.
+ */
+ if (flags & MAP_SHARED) {
+ CPUState *cpu = thread_cpu;
+ if (!(cpu->tcg_cflags & CF_PARALLEL)) {
+ cpu->tcg_cflags |= CF_PARALLEL;
+ tb_flush(cpu);
+ }
+ }
+
real_start = start & qemu_host_page_mask;
host_offset = offset & qemu_host_page_mask;
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 974dd46c9a17..54037db8d66d 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -4603,6 +4603,7 @@ static inline abi_ulong target_shmlba(CPUArchState
*cpu_env)
static inline abi_ulong do_shmat(CPUArchState *cpu_env,
int shmid, abi_ulong shmaddr, int shmflg)
{
+ CPUState *cpu = env_cpu(cpu_env);
abi_long raddr;
void *host_raddr;
struct shmid_ds shm_info;
@@ -4633,6 +4634,17 @@ static inline abi_ulong do_shmat(CPUArchState *cpu_env,
mmap_lock();
+ /*
+ * We're mapping shared memory, so ensure we generate code for parallel
+ * execution and flush old translations. This will work up to the level
+ * supported by the host -- anything that requires EXCP_ATOMIC will not
+ * be atomic with respect to an external process.
+ */
+ if (!(cpu->tcg_cflags & CF_PARALLEL)) {
+ cpu->tcg_cflags |= CF_PARALLEL;
+ tb_flush(cpu);
+ }
+
if (shmaddr)
host_raddr = shmat(shmid, (void *)g2h_untagged(shmaddr), shmflg);
else {
--
2.31.1
- [PULL 0/9] Linux user for 6.1 patches, Laurent Vivier, 2021/06/21
- [PULL 2/9] linux-user: Disable static assert involving __SIGRTMAX if it is missing, Laurent Vivier, 2021/06/21
- [PULL 1/9] linux-user: Set CF_PARALLEL when mapping shared memory,
Laurent Vivier <=
- [PULL 4/9] linux-user: Implement pivot_root, Laurent Vivier, 2021/06/21
- [PULL 5/9] linux-user: Let sigaction query SIGKILL/SIGSTOP, Laurent Vivier, 2021/06/21
- [PULL 9/9] linux-user: Use public sigev_notify_thread_id member if available, Laurent Vivier, 2021/06/21
- [PULL 7/9] linux-user: Check for ieee128 fpbits in PPC64 HWCAP2 feature list, Laurent Vivier, 2021/06/21
- [PULL 8/9] linux-user: Fix incorrect use of feature-test-macros, Laurent Vivier, 2021/06/21
- [PULL 3/9] linux-user/trace-events: fix minor typo in format string, Laurent Vivier, 2021/06/21
- [PULL 6/9] tests/tcg/linux-test: Check that sigaction can query SIGKILL/SIGSTOP, Laurent Vivier, 2021/06/21
- Re: [PULL 0/9] Linux user for 6.1 patches, Peter Maydell, 2021/06/22