Messages in this thread Patch in this message | | | Date | Fri, 7 Jul 2006 11:53:11 -0400 | From | Chuck Ebbert <> | Subject | [patch] i386: use thread_info flags for debug regs and IO bitmaps |
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From: Stephane Eranian <eranian@hpl.hp.com>
Use thread info flags to track use of debug registers and IO bitmaps.
- add TIF_DEBUG to track when debug registers are active - add TIF_IO_BITMAP to track when I/O bitmap is used - modify __switch_to() to use the new TIF flags
Signed-off-by: Stephane Eranian <eranian@hpl.hp.com> Signed-off-by: Chuck Ebbert <76306.1226@compuserve.com>
---
I didn't see this patch get merged anywhere. Can you merge it, Andrew? It's independent of the x86_64 version that Andi has merged in his tree.
arch/i386/kernel/ioport.c | 1 arch/i386/kernel/process.c | 50 +++++++++++++++++++++++------------------ arch/i386/kernel/ptrace.c | 5 +++- include/asm-i386/thread_info.h | 7 +++++ 4 files changed, 41 insertions(+), 22 deletions(-)
--- 2.6.18-rc1-nb.orig/arch/i386/kernel/ioport.c +++ 2.6.18-rc1-nb/arch/i386/kernel/ioport.c @@ -79,6 +79,7 @@ asmlinkage long sys_ioperm(unsigned long memset(bitmap, 0xff, IO_BITMAP_BYTES); t->io_bitmap_ptr = bitmap; + set_thread_flag(TIF_IO_BITMAP); } /* --- 2.6.18-rc1-nb.orig/arch/i386/kernel/process.c +++ 2.6.18-rc1-nb/arch/i386/kernel/process.c @@ -359,16 +359,16 @@ EXPORT_SYMBOL(kernel_thread); */ void exit_thread(void) { - struct task_struct *tsk = current; - struct thread_struct *t = &tsk->thread; - /* The process may have allocated an io port bitmap... nuke it. */ - if (unlikely(NULL != t->io_bitmap_ptr)) { + if (unlikely(test_thread_flag(TIF_IO_BITMAP))) { + struct task_struct *tsk = current; + struct thread_struct *t = &tsk->thread; int cpu = get_cpu(); struct tss_struct *tss = &per_cpu(init_tss, cpu); kfree(t->io_bitmap_ptr); t->io_bitmap_ptr = NULL; + clear_thread_flag(TIF_IO_BITMAP); /* * Careful, clear this in the TSS too: */ @@ -387,6 +387,7 @@ void flush_thread(void) memset(tsk->thread.debugreg, 0, sizeof(unsigned long)*8); memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array)); + clear_tsk_thread_flag(tsk, TIF_DEBUG); /* * Forget coprocessor state.. */ @@ -431,7 +432,7 @@ int copy_thread(int nr, unsigned long cl savesegment(gs,p->thread.gs); tsk = current; - if (unlikely(NULL != tsk->thread.io_bitmap_ptr)) { + if (unlikely(test_tsk_thread_flag(tsk, TIF_IO_BITMAP))) { p->thread.io_bitmap_ptr = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL); if (!p->thread.io_bitmap_ptr) { p->thread.io_bitmap_max = 0; @@ -439,6 +440,7 @@ int copy_thread(int nr, unsigned long cl } memcpy(p->thread.io_bitmap_ptr, tsk->thread.io_bitmap_ptr, IO_BITMAP_BYTES); + set_tsk_thread_flag(p, TIF_IO_BITMAP); } /* @@ -533,10 +535,24 @@ int dump_task_regs(struct task_struct *t return 1; } -static inline void -handle_io_bitmap(struct thread_struct *next, struct tss_struct *tss) +static inline void __switch_to_xtra(struct task_struct *next_p, + struct tss_struct *tss) { - if (!next->io_bitmap_ptr) { + struct thread_struct *next; + + next = &next_p->thread; + + if (test_tsk_thread_flag(next_p, TIF_DEBUG)) { + set_debugreg(next->debugreg[0], 0); + set_debugreg(next->debugreg[1], 1); + set_debugreg(next->debugreg[2], 2); + set_debugreg(next->debugreg[3], 3); + /* no 4 and 5 */ + set_debugreg(next->debugreg[6], 6); + set_debugreg(next->debugreg[7], 7); + } + + if (!test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) { /* * Disable the bitmap via an invalid offset. We still cache * the previous bitmap owner and the IO bitmap contents: @@ -544,6 +560,7 @@ handle_io_bitmap(struct thread_struct *n tss->io_bitmap_base = INVALID_IO_BITMAP_OFFSET; return; } + if (likely(next == tss->io_bitmap_owner)) { /* * Previous owner of the bitmap (hence the bitmap content) @@ -671,20 +688,11 @@ struct task_struct fastcall * __switch_t set_iopl_mask(next->iopl); /* - * Now maybe reload the debug registers + * Now maybe handle debug registers and/or IO bitmaps */ - if (unlikely(next->debugreg[7])) { - set_debugreg(next->debugreg[0], 0); - set_debugreg(next->debugreg[1], 1); - set_debugreg(next->debugreg[2], 2); - set_debugreg(next->debugreg[3], 3); - /* no 4 and 5 */ - set_debugreg(next->debugreg[6], 6); - set_debugreg(next->debugreg[7], 7); - } - - if (unlikely(prev->io_bitmap_ptr || next->io_bitmap_ptr)) - handle_io_bitmap(next, tss); + if (unlikely((task_thread_info(next_p)->flags & _TIF_WORK_CTXSW)) + || test_tsk_thread_flag(prev_p, TIF_IO_BITMAP)) + __switch_to_xtra(next_p, tss); disable_tsc(prev_p, next_p); --- 2.6.18-rc1-nb.orig/arch/i386/kernel/ptrace.c +++ 2.6.18-rc1-nb/arch/i386/kernel/ptrace.c @@ -468,8 +468,11 @@ long arch_ptrace(struct task_struct *chi for(i=0; i<4; i++) if ((0x5f54 >> ((data >> (16 + 4*i)) & 0xf)) & 1) goto out_tsk; + if (data) + set_tsk_thread_flag(child, TIF_DEBUG); + else + clear_tsk_thread_flag(child, TIF_DEBUG); } - addr -= (long) &dummy->u_debugreg; addr = addr >> 2; child->thread.debugreg[addr] = data; --- 2.6.18-rc1-nb.orig/include/asm-i386/thread_info.h +++ 2.6.18-rc1-nb/include/asm-i386/thread_info.h @@ -140,6 +140,8 @@ static inline struct thread_info *curren #define TIF_SECCOMP 8 /* secure computing */ #define TIF_RESTORE_SIGMASK 9 /* restore signal mask in do_signal() */ #define TIF_MEMDIE 16 +#define TIF_DEBUG 17 /* uses debug registers */ +#define TIF_IO_BITMAP 18 /* uses I/O bitmap */ #define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE) #define _TIF_NOTIFY_RESUME (1<<TIF_NOTIFY_RESUME) @@ -151,6 +153,8 @@ static inline struct thread_info *curren #define _TIF_SYSCALL_AUDIT (1<<TIF_SYSCALL_AUDIT) #define _TIF_SECCOMP (1<<TIF_SECCOMP) #define _TIF_RESTORE_SIGMASK (1<<TIF_RESTORE_SIGMASK) +#define _TIF_DEBUG (1<<TIF_DEBUG) +#define _TIF_IO_BITMAP (1<<TIF_IO_BITMAP) /* work to do on interrupt/exception return */ #define _TIF_WORK_MASK \ @@ -159,6 +163,9 @@ static inline struct thread_info *curren /* work to do on any return to u-space */ #define _TIF_ALLWORK_MASK (0x0000FFFF & ~_TIF_SECCOMP) +/* flags to check in __switch_to() */ +#define _TIF_WORK_CTXSW (_TIF_DEBUG|_TIF_IO_BITMAP) + /* * Thread-synchronous status. * -- Chuck "You can't read a newspaper if you can't read." --George W. 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