diff options
| author | Chang S. Bae <chang.seok.bae@intel.com> | 2020-05-28 16:13:53 -0400 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2020-06-18 15:47:02 +0200 |
| commit | 005f141e5d5e05d3986539567d0bc5aa2f4dc640 (patch) | |
| tree | 8483e6be0a7c3040c858b1dd5026c176b4f1e551 | |
| parent | 673903495c85137791d5820d690229efe09c8f7b (diff) | |
x86/process/64: Use FSGSBASE instructions on thread copy and ptrace
When FSGSBASE is enabled, copying threads and reading fsbase and gsbase
using ptrace must read the actual values.
When copying a thread, use save_fsgs() and copy the saved values. For
ptrace, the bases must be read from memory regardless of the selector if
FSGSBASE is enabled.
[ tglx: Invoke __rdgsbase_inactive() with interrupts disabled ]
[ luto: Massage changelog ]
Suggested-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/1557309753-24073-9-git-send-email-chang.seok.bae@intel.com
Link: https://lkml.kernel.org/r/20200528201402.1708239-8-sashal@kernel.org
| -rw-r--r-- | arch/x86/kernel/process.c | 10 | ||||
| -rw-r--r-- | arch/x86/kernel/process_64.c | 6 |
2 files changed, 10 insertions, 6 deletions
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index f362ce0d5ac0..216c88df1919 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -140,10 +140,12 @@ int copy_thread_tls(unsigned long clone_flags, unsigned long sp, memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps)); #ifdef CONFIG_X86_64 - savesegment(gs, p->thread.gsindex); - p->thread.gsbase = p->thread.gsindex ? 0 : current->thread.gsbase; - savesegment(fs, p->thread.fsindex); - p->thread.fsbase = p->thread.fsindex ? 0 : current->thread.fsbase; + current_save_fsgs(); + p->thread.fsindex = current->thread.fsindex; + p->thread.fsbase = current->thread.fsbase; + p->thread.gsindex = current->thread.gsindex; + p->thread.gsbase = current->thread.gsbase; + savesegment(es, p->thread.es); savesegment(ds, p->thread.ds); #else diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index 8ccc587c311b..d618969cea66 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -426,7 +426,8 @@ unsigned long x86_fsbase_read_task(struct task_struct *task) if (task == current) fsbase = x86_fsbase_read_cpu(); - else if (task->thread.fsindex == 0) + else if (static_cpu_has(X86_FEATURE_FSGSBASE) || + (task->thread.fsindex == 0)) fsbase = task->thread.fsbase; else fsbase = x86_fsgsbase_read_task(task, task->thread.fsindex); @@ -440,7 +441,8 @@ unsigned long x86_gsbase_read_task(struct task_struct *task) if (task == current) gsbase = x86_gsbase_read_cpu_inactive(); - else if (task->thread.gsindex == 0) + else if (static_cpu_has(X86_FEATURE_FSGSBASE) || + (task->thread.gsindex == 0)) gsbase = task->thread.gsbase; else gsbase = x86_fsgsbase_read_task(task, task->thread.gsindex); |