From e696c231bebf5f17fe0c5e465c01511320668054 Mon Sep 17 00:00:00 2001 From: "Chang S. Bae" Date: Tue, 18 Sep 2018 16:08:54 -0700 Subject: x86/fsgsbase/64: Make ptrace use the new FS/GS base helpers Use the new FS/GS base helper functions in in the platform specific ptrace implementation of the following APIs: PTRACE_ARCH_PRCTL, PTRACE_SETREG, PTRACE_GETREG, etc. The fsgsbase code is more abstracted out this way and the FS/GS-update mechanism will be easier to change this way. [ mingo: Wrote new changelog. ] Based-on-code-from: Andy Lutomirski Signed-off-by: Chang S. Bae Cc: Andy Lutomirski Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Dave Hansen Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Markus T Metzger Cc: Peter Zijlstra Cc: Ravi Shankar Cc: Rik van Riel Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1537312139-5580-4-git-send-email-chang.seok.bae@intel.com Signed-off-by: Ingo Molnar --- arch/x86/kernel/process_64.c | 49 +++++++++----------------------------------- 1 file changed, 10 insertions(+), 39 deletions(-) (limited to 'arch/x86/kernel/process_64.c') diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index 2a53ff8d1baf..e5fb0c3dee4d 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -287,8 +287,8 @@ static __always_inline void load_seg_legacy(unsigned short prev_index, } } -unsigned long x86_fsgsbase_read_task(struct task_struct *task, - unsigned short selector) +static unsigned long x86_fsgsbase_read_task(struct task_struct *task, + unsigned short selector) { unsigned short idx = selector >> 3; unsigned long base; @@ -751,54 +751,25 @@ static long prctl_map_vdso(const struct vdso_image *image, unsigned long addr) long do_arch_prctl_64(struct task_struct *task, int option, unsigned long arg2) { int ret = 0; - int doit = task == current; - int cpu; switch (option) { - case ARCH_SET_GS: - if (arg2 >= TASK_SIZE_MAX) - return -EPERM; - cpu = get_cpu(); - task->thread.gsindex = 0; - task->thread.gsbase = arg2; - if (doit) { - load_gs_index(0); - ret = wrmsrl_safe(MSR_KERNEL_GS_BASE, arg2); - } - put_cpu(); + case ARCH_SET_GS: { + ret = x86_gsbase_write_task(task, arg2); break; - case ARCH_SET_FS: - /* Not strictly needed for fs, but do it for symmetry - with gs */ - if (arg2 >= TASK_SIZE_MAX) - return -EPERM; - cpu = get_cpu(); - task->thread.fsindex = 0; - task->thread.fsbase = arg2; - if (doit) { - /* set the selector to 0 to not confuse __switch_to */ - loadsegment(fs, 0); - ret = wrmsrl_safe(MSR_FS_BASE, arg2); - } - put_cpu(); + } + case ARCH_SET_FS: { + ret = x86_fsbase_write_task(task, arg2); break; + } case ARCH_GET_FS: { - unsigned long base; + unsigned long base = x86_fsbase_read_task(task); - if (doit) - rdmsrl(MSR_FS_BASE, base); - else - base = task->thread.fsbase; ret = put_user(base, (unsigned long __user *)arg2); break; } case ARCH_GET_GS: { - unsigned long base; + unsigned long base = x86_gsbase_read_task(task); - if (doit) - rdmsrl(MSR_KERNEL_GS_BASE, base); - else - base = task->thread.gsbase; ret = put_user(base, (unsigned long __user *)arg2); break; } -- cgit v1.2.3