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Subject[PATCH 2/4] traps: i386: factor out lazy io-bitmap copy
Date
x86_64 does not do the lazy io-bitmap dance. Putting it in
its own function makes i386's do_general_protection look
much more like x86_64's.

Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm>
---
arch/x86/kernel/traps_32.c | 76 +++++++++++++++++++++++++-------------------
1 files changed, 43 insertions(+), 33 deletions(-)

diff --git a/arch/x86/kernel/traps_32.c b/arch/x86/kernel/traps_32.c
index dd183a2..78113d3 100644
--- a/arch/x86/kernel/traps_32.c
+++ b/arch/x86/kernel/traps_32.c
@@ -96,6 +96,47 @@ die_if_kernel(const char *str, struct pt_regs *regs, long err)
die(str, regs, err);
}

+/*
+ * Perform the lazy TSS's I/O bitmap copy. If the TSS has an
+ * invalid offset set (the LAZY one) and the faulting thread has
+ * a valid I/O bitmap pointer, we copy the I/O bitmap in the TSS,
+ * we set the offset field correctly and return 1.
+ */
+static int lazy_iobitmap_copy(void)
+{
+ struct thread_struct *thread;
+ struct tss_struct *tss;
+ int cpu;
+
+ cpu = get_cpu();
+ tss = &per_cpu(init_tss, cpu);
+ thread = &current->thread;
+
+ if (tss->x86_tss.io_bitmap_base == INVALID_IO_BITMAP_OFFSET_LAZY &&
+ thread->io_bitmap_ptr) {
+ memcpy(tss->io_bitmap, thread->io_bitmap_ptr,
+ thread->io_bitmap_max);
+ /*
+ * If the previously set map was extending to higher ports
+ * than the current one, pad extra space with 0xff (no access).
+ */
+ if (thread->io_bitmap_max < tss->io_bitmap_max) {
+ memset((char *) tss->io_bitmap +
+ thread->io_bitmap_max, 0xff,
+ tss->io_bitmap_max - thread->io_bitmap_max);
+ }
+ tss->io_bitmap_max = thread->io_bitmap_max;
+ tss->x86_tss.io_bitmap_base = IO_BITMAP_OFFSET;
+ tss->io_bitmap_owner = thread;
+ put_cpu();
+
+ return 1;
+ }
+ put_cpu();
+
+ return 0;
+}
+
static void __kprobes
do_trap(int trapnr, int signr, char *str, struct pt_regs *regs,
long error_code, siginfo_t *info)
@@ -188,44 +229,13 @@ void __kprobes
do_general_protection(struct pt_regs *regs, long error_code)
{
struct task_struct *tsk;
- struct thread_struct *thread;
- struct tss_struct *tss;
- int cpu;

conditional_sti(regs);

- cpu = get_cpu();
- tss = &per_cpu(init_tss, cpu);
- thread = &current->thread;
-
- /*
- * Perform the lazy TSS's I/O bitmap copy. If the TSS has an
- * invalid offset set (the LAZY one) and the faulting thread has
- * a valid I/O bitmap pointer, we copy the I/O bitmap in the TSS
- * and we set the offset field correctly. Then we let the CPU to
- * restart the faulting instruction.
- */
- if (tss->x86_tss.io_bitmap_base == INVALID_IO_BITMAP_OFFSET_LAZY &&
- thread->io_bitmap_ptr) {
- memcpy(tss->io_bitmap, thread->io_bitmap_ptr,
- thread->io_bitmap_max);
- /*
- * If the previously set map was extending to higher ports
- * than the current one, pad extra space with 0xff (no access).
- */
- if (thread->io_bitmap_max < tss->io_bitmap_max) {
- memset((char *) tss->io_bitmap +
- thread->io_bitmap_max, 0xff,
- tss->io_bitmap_max - thread->io_bitmap_max);
- }
- tss->io_bitmap_max = thread->io_bitmap_max;
- tss->x86_tss.io_bitmap_base = IO_BITMAP_OFFSET;
- tss->io_bitmap_owner = thread;
- put_cpu();
-
+ if (lazy_iobitmap_copy()) {
+ /* restart the faulting instruction */
return;
}
- put_cpu();

if (regs->flags & X86_VM_MASK)
goto gp_in_vm86;
--
1.5.4.3


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