From patchwork Wed Feb 27 03:04:21 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [v3,6/6] powerpc/kgdb: remove copying the thread_info Date: Tue, 26 Feb 2013 17:04:21 -0000 From: Tiejun Chen X-Patchwork-Id: 223477 Message-Id: <1361934261-31840-7-git-send-email-tiejun.chen@windriver.com> To: , Cc: linuxppc-dev@lists.ozlabs.org Currently BookE and Book3E always copy the thread_info from the kernel stack when we enter the debug exception, so we can remove these action here to avoid copying again. Signed-off-by: Tiejun Chen --- arch/powerpc/kernel/kgdb.c | 28 ---------------------------- 1 file changed, 28 deletions(-) diff --git a/arch/powerpc/kernel/kgdb.c b/arch/powerpc/kernel/kgdb.c index 1a57307..e954888 100644 --- a/arch/powerpc/kernel/kgdb.c +++ b/arch/powerpc/kernel/kgdb.c @@ -153,39 +153,11 @@ static int kgdb_handle_breakpoint(struct pt_regs *regs) static int kgdb_singlestep(struct pt_regs *regs) { - struct thread_info *thread_info, *exception_thread_info; - struct thread_info *backup_current_thread_info; - if (user_mode(regs)) return 0; - backup_current_thread_info = (struct thread_info *)kmalloc(sizeof(struct thread_info), GFP_KERNEL); - /* - * On Book E and perhaps other processors, singlestep is handled on - * the critical exception stack. This causes current_thread_info() - * to fail, since it it locates the thread_info by masking off - * the low bits of the current stack pointer. We work around - * this issue by copying the thread_info from the kernel stack - * before calling kgdb_handle_exception, and copying it back - * afterwards. On most processors the copy is avoided since - * exception_thread_info == thread_info. - */ - thread_info = (struct thread_info *)(regs->gpr[1] & ~(THREAD_SIZE-1)); - exception_thread_info = current_thread_info(); - - if (thread_info != exception_thread_info) { - /* Save the original current_thread_info. */ - memcpy(backup_current_thread_info, exception_thread_info, sizeof *thread_info); - memcpy(exception_thread_info, thread_info, sizeof *thread_info); - } - kgdb_handle_exception(0, SIGTRAP, 0, regs); - if (thread_info != exception_thread_info) - /* Restore current_thread_info lastly. */ - memcpy(exception_thread_info, backup_current_thread_info, sizeof *thread_info); - - kfree(backup_current_thread_info); return 1; }