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The 32-bit and 64-bit versions of copy_thread have functionally identical handling for copying the I/O bitmap, modulo differences in error handling. Clean up the error paths in both by moving the copy of the I/O bitmap to the end, to eliminate the need to free it if subsequent copy steps fail; move the resulting identical code to a static inline in a common header. Signed-off-by: Josh Triplett

The 32-bit and 64-bit versions of copy_thread have functionally identical handling for copying the I/O bitmap, modulo differences in error handling. Clean up the error paths in both by moving the copy of the I/O bitmap to the end, to eliminate the need to free it if subsequent copy steps fail; move the resulting identical code to a static inline in a common header. Signed-off-by: Josh Triplett

...ssions now > lives in process-io.h as several new inline functions, which become > no-ops without CONFIG_X86_IOPORT. > > bloat-o-meter results: > > add/remove: 0/4 grow/shrink: 4/9 up/down: 83/-9074 (-8991) > function old new delta > drop_fpu 80 160 +80 > perf_event_init_task 638 639 +1 > perf_event_exec 192 193 +1 > perf_event_aux 132 133 +1 > test_tsk_thread_flag...

...code dealing with userspace I/O permissions now lives in process-io.h as several new inline functions, which become no-ops without CONFIG_X86_IOPORT. bloat-o-meter results: add/remove: 0/4 grow/shrink: 4/9 up/down: 83/-9074 (-8991) function old new delta drop_fpu 80 160 +80 perf_event_init_task 638 639 +1 perf_event_exec 192 193 +1 perf_event_aux 132 133 +1 test_tsk_thread_flag 10...

...code dealing with userspace I/O permissions now lives in process-io.h as several new inline functions, which become no-ops without CONFIG_X86_IOPORT. bloat-o-meter results: add/remove: 0/4 grow/shrink: 4/9 up/down: 83/-9074 (-8991) function old new delta drop_fpu 80 160 +80 perf_event_init_task 638 639 +1 perf_event_exec 192 193 +1 perf_event_aux 132 133 +1 test_tsk_thread_flag 10...

...e size of several major kernel data structures, drops a bit of code from several task-related hot paths, and reduces the attack surface of the kernel. bloat-o-meter results: add/remove: 0/4 grow/shrink: 4/9 up/down: 83/-9074 (-8991) function old new delta drop_fpu 80 160 +80 perf_event_init_task 638 639 +1 perf_event_exec 192 193 +1 perf_event_aux 132 133 +1 test_tsk_thread_flag 10...

...e size of several major kernel data structures, drops a bit of code from several task-related hot paths, and reduces the attack surface of the kernel. bloat-o-meter results: add/remove: 0/4 grow/shrink: 4/9 up/down: 83/-9074 (-8991) function old new delta drop_fpu 80 160 +80 perf_event_init_task 638 639 +1 perf_event_exec 192 193 +1 perf_event_aux 132 133 +1 test_tsk_thread_flag 10...

This patch series makes it possible to compile out the userspace IO system calls, iopl and ioperm. The first patch does some 32/64 unification in copy_thread to make subsequent changes easier. The second patch simplifies the complex calculation of the TSS segment limit, which also makes it easier to change in the last patch. Patches 3-9 introduce helpers to make it easier to compile out IO.

This patch series makes it possible to compile out the userspace IO system calls, iopl and ioperm. The first patch does some 32/64 unification in copy_thread to make subsequent changes easier. The second patch simplifies the complex calculation of the TSS segment limit, which also makes it easier to change in the last patch. Patches 3-9 introduce helpers to make it easier to compile out IO.

...p;per_cpu(init_tss, get_cpu()); - - t->io_bitmap_ptr = NULL; - clear_thread_flag(TIF_IO_BITMAP); - /* - * Careful, clear this in the TSS too: - */ - memset(tss->io_bitmap, 0xff, t->io_bitmap_max); - t->io_bitmap_max = 0; - put_cpu(); - kfree(bp); - } - + exit_thread_io(me); drop_fpu(me); } @@ -222,19 +208,7 @@ void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p, hard_enable_TSC(); } - if (test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) { - /* - * Copy the relevant range of the IO bitmap. - * Normally this is 128 bytes or less: - */ - me...

...p;per_cpu(init_tss, get_cpu()); - - t->io_bitmap_ptr = NULL; - clear_thread_flag(TIF_IO_BITMAP); - /* - * Careful, clear this in the TSS too: - */ - memset(tss->io_bitmap, 0xff, t->io_bitmap_max); - t->io_bitmap_max = 0; - put_cpu(); - kfree(bp); - } - + exit_thread_io(me); drop_fpu(me); } @@ -222,19 +208,7 @@ void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p, hard_enable_TSC(); } - if (test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) { - /* - * Copy the relevant range of the IO bitmap. - * Normally this is 128 bytes or less: - */ - me...

...this in the TSS too: > - */ > - memset(tss->io_bitmap, 0xff, t->io_bitmap_max); > - t->io_bitmap_max = 0; > - put_cpu(); > - kfree(bp); > - } > - > + exit_thread_io(me); > drop_fpu(me); > } > > @@ -222,19 +208,7 @@ void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p, > hard_enable_TSC(); > } > > - if (test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) { > - /* > -...

...this in the TSS too: > - */ > - memset(tss->io_bitmap, 0xff, t->io_bitmap_max); > - t->io_bitmap_max = 0; > - put_cpu(); > - kfree(bp); > - } > - > + exit_thread_io(me); > drop_fpu(me); > } > > @@ -222,19 +208,7 @@ void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p, > hard_enable_TSC(); > } > > - if (test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) { > - /* > -...

This patch series makes it possible to compile out the iopl and ioperm system calls, which allow privileged processes to request permission to directly poke I/O ports from userspace. Nothing on a modern Linux system uses these calls anymore, and anything new should be using /dev/port instead, or better yet writing a driver. Copying the bloat-o-meter stats from the final patch: 32-bit

This patch series makes it possible to compile out the iopl and ioperm system calls, which allow privileged processes to request permission to directly poke I/O ports from userspace. Nothing on a modern Linux system uses these calls anymore, and anything new should be using /dev/port instead, or better yet writing a driver. Copying the bloat-o-meter stats from the final patch: 32-bit

...ULL; > - clear_thread_flag(TIF_IO_BITMAP); > - /* > - * Careful, clear this in the TSS too: > - */ > - memset(tss->io_bitmap, 0xff, t->io_bitmap_max); > - t->io_bitmap_max = 0; > - put_cpu(); > - kfree(bp); > - } > - > + exit_thread_io(me); > drop_fpu(me); > } > > @@ -222,19 +208,7 @@ void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p, > hard_enable_TSC(); > } > > - if (test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) { > - /* > - * Copy the relevant range of the IO bitmap. > -...

...ULL; > - clear_thread_flag(TIF_IO_BITMAP); > - /* > - * Careful, clear this in the TSS too: > - */ > - memset(tss->io_bitmap, 0xff, t->io_bitmap_max); > - t->io_bitmap_max = 0; > - put_cpu(); > - kfree(bp); > - } > - > + exit_thread_io(me); > drop_fpu(me); > } > > @@ -222,19 +208,7 @@ void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p, > hard_enable_TSC(); > } > > - if (test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) { > - /* > - * Copy the relevant range of the IO bitmap. > -...

The 32-bit and 64-bit versions of copy_thread have functionally identical handling for copying the I/O bitmap, modulo differences in error handling. Clean up the error paths in both by moving the copy of the I/O bitmap to the end, to eliminate the need to free it if subsequent copy steps fail; move the resulting identical code to a static inline in a common header. Signed-off-by: Josh Triplett

The 32-bit and 64-bit versions of copy_thread have functionally identical handling for copying the I/O bitmap, modulo differences in error handling. Clean up the error paths in both by moving the copy of the I/O bitmap to the end, to eliminate the need to free it if subsequent copy steps fail; move the resulting identical code to a static inline in a common header. Signed-off-by: Josh Triplett