The ia32_compat attribute is a weird thing. It mirrors TIF_IA32 and
TIF_X32 and is used only in two very unrelated places: (1) to decide if
the vsyscall page is accessible (2) for uprobes to find whether the
patched instruction is 32 or 64 bit.
In preparation to remove the TIF flags, a new mechanism is required for
ia32_compat, but given its odd semantics, adding a real flags field which
configures these specific behaviours is the best option.
So, set_personality_x64() can ask for the vsyscall page, which is not
available in x32/ia32 and set_personality_ia32() can configure the uprobe
code as needed.
uprobe cannot rely on other methods like user_64bit_mode() to decide how
to patch, so it needs some specific flag like this.
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Andy Lutomirski<luto@kernel.org>
Link: https://lore.kernel.org/r/20201004032536.1229030-10-krisman@collabora.com
struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
{
#ifdef CONFIG_COMPAT
struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
{
#ifdef CONFIG_COMPAT
- if (!mm || mm->context.ia32_compat)
+ if (!mm || !(mm->context.flags & MM_CONTEXT_HAS_VSYSCALL))
return NULL;
#endif
if (vsyscall_mode == NONE)
return NULL;
#endif
if (vsyscall_mode == NONE)
#include <linux/rwsem.h>
#include <linux/mutex.h>
#include <linux/atomic.h>
#include <linux/rwsem.h>
#include <linux/mutex.h>
#include <linux/atomic.h>
+#include <linux/bits.h>
+
+/* Uprobes on this MM assume 32-bit code */
+#define MM_CONTEXT_UPROBE_IA32 BIT(0)
+/* vsyscall page is accessible on this MM */
+#define MM_CONTEXT_HAS_VSYSCALL BIT(1)
/*
* x86 has arch-specific MMU state beyond what lives in mm_struct.
/*
* x86 has arch-specific MMU state beyond what lives in mm_struct.
#endif
#ifdef CONFIG_X86_64
#endif
#ifdef CONFIG_X86_64
- /* True if mm supports a task running in 32 bit compatibility mode. */
- unsigned short ia32_compat;
#endif
struct mutex lock;
#endif
struct mutex lock;
static inline bool is_64bit_mm(struct mm_struct *mm)
{
return !IS_ENABLED(CONFIG_IA32_EMULATION) ||
static inline bool is_64bit_mm(struct mm_struct *mm)
{
return !IS_ENABLED(CONFIG_IA32_EMULATION) ||
- !(mm->context.ia32_compat == TIF_IA32);
+ !(mm->context.flags & MM_CONTEXT_UPROBE_IA32);
}
#else
static inline bool is_64bit_mm(struct mm_struct *mm)
}
#else
static inline bool is_64bit_mm(struct mm_struct *mm)
/* Pretend that this comes from a 64bit execve */
task_pt_regs(current)->orig_ax = __NR_execve;
current_thread_info()->status &= ~TS_COMPAT;
/* Pretend that this comes from a 64bit execve */
task_pt_regs(current)->orig_ax = __NR_execve;
current_thread_info()->status &= ~TS_COMPAT;
-
- /* Ensure the corresponding mm is not marked. */
- current->mm->context.ia32_compat = 0;
+ current->mm->context.flags = MM_CONTEXT_HAS_VSYSCALL;
/* TBD: overwrites user setup. Should have two bits.
But 64bit processes have always behaved this way,
/* TBD: overwrites user setup. Should have two bits.
But 64bit processes have always behaved this way,
clear_thread_flag(TIF_IA32);
set_thread_flag(TIF_X32);
if (current->mm)
clear_thread_flag(TIF_IA32);
set_thread_flag(TIF_X32);
if (current->mm)
- current->mm->context.ia32_compat = TIF_X32;
+ current->mm->context.flags = 0;
+
current->personality &= ~READ_IMPLIES_EXEC;
/*
* in_32bit_syscall() uses the presence of the x32 syscall bit
current->personality &= ~READ_IMPLIES_EXEC;
/*
* in_32bit_syscall() uses the presence of the x32 syscall bit
#ifdef CONFIG_IA32_EMULATION
set_thread_flag(TIF_IA32);
clear_thread_flag(TIF_X32);
#ifdef CONFIG_IA32_EMULATION
set_thread_flag(TIF_IA32);
clear_thread_flag(TIF_X32);
- if (current->mm)
- current->mm->context.ia32_compat = TIF_IA32;
+ if (current->mm) {
+ /*
+ * uprobes applied to this MM need to know this and
+ * cannot use user_64bit_mode() at that time.
+ */
+ current->mm->context.flags = MM_CONTEXT_UPROBE_IA32;
+ }
+
current->personality |= force_personality32;
/* Prepare the first "return" to user space */
task_pt_regs(current)->orig_ax = __NR_ia32_execve;
current->personality |= force_personality32;
/* Prepare the first "return" to user space */
task_pt_regs(current)->orig_ax = __NR_ia32_execve;