[PATCH 0/3] x86: do not save callee-preserved registers around lockdep_sys_exit_thunk
Recent change to struct pt_regs handling in entry.S, among other things, changed how callee-preserved registers are saved around call to lockdep_sys_exit_thunk: #define LOCKDEP_SYS_EXIT_IRQ \ TRACE_IRQS_ON; \ sti; \ SAVE_EXTRA_REGS; \<=== HERE LOCKDEP_SYS_EXIT; \ RESTORE_EXTRA_REGS; \ <=== HERE The change is in fact a bit fragile: now we assume that LOCKDEP_SYS_EXIT_IRQ macro is used only when there is a struct pt_regs on the stack. So far this assumption is true, but it is probably a coincidence. We can revert back to pushing registers, but this callee-preserved registers saving appears bogus. It is not necessary: they _are_ callee-preserved, and lockdep_sys_exit() does not touch them on the stack either. First two patches clean up #define maze so that we can see that LOCKDEP_SYS_EXIT macro call above is merely "call lockdep_sys_exit_thunk". Last patch removes SAVE/RESTORE. I tested this patch series and everything seems to run fine on a lockdep-enabled kernel with these lines removed. Denys Vlasenko (3): x86: move ARCH_LOCKDEP_SYS_EXIT[IRQ] defines closer to their users x86: fold ARCH_LOCKDEP_SYS_EXIT defines into their users x86: do not save callee-preserved registers around lockdep_sys_exit_thunk arch/x86/include/asm/irqflags.h | 45 + 1 file changed, 19 insertions(+), 26 deletions(-) CC: Linus Torvalds CC: Steven Rostedt CC: Ingo Molnar CC: Borislav Petkov CC: "H. Peter Anvin" CC: Andy Lutomirski CC: Oleg Nesterov CC: Frederic Weisbecker CC: Alexei Starovoitov CC: Will Drewry CC: Kees Cook CC: x...@kernel.org CC: linux-kernel@vger.kernel.org -- 1.8.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[PATCH 0/3] x86: do not save callee-preserved registers around lockdep_sys_exit_thunk
Recent change to struct pt_regs handling in entry.S, among other things, changed how callee-preserved registers are saved around call to lockdep_sys_exit_thunk: #define LOCKDEP_SYS_EXIT_IRQ \ TRACE_IRQS_ON; \ sti; \ SAVE_EXTRA_REGS; \=== HERE LOCKDEP_SYS_EXIT; \ RESTORE_EXTRA_REGS; \ === HERE The change is in fact a bit fragile: now we assume that LOCKDEP_SYS_EXIT_IRQ macro is used only when there is a struct pt_regs on the stack. So far this assumption is true, but it is probably a coincidence. We can revert back to pushing registers, but this callee-preserved registers saving appears bogus. It is not necessary: they _are_ callee-preserved, and lockdep_sys_exit() does not touch them on the stack either. First two patches clean up #define maze so that we can see that LOCKDEP_SYS_EXIT macro call above is merely call lockdep_sys_exit_thunk. Last patch removes SAVE/RESTORE. I tested this patch series and everything seems to run fine on a lockdep-enabled kernel with these lines removed. Denys Vlasenko (3): x86: move ARCH_LOCKDEP_SYS_EXIT[IRQ] defines closer to their users x86: fold ARCH_LOCKDEP_SYS_EXIT defines into their users x86: do not save callee-preserved registers around lockdep_sys_exit_thunk arch/x86/include/asm/irqflags.h | 45 + 1 file changed, 19 insertions(+), 26 deletions(-) CC: Linus Torvalds torva...@linux-foundation.org CC: Steven Rostedt rost...@goodmis.org CC: Ingo Molnar mi...@kernel.org CC: Borislav Petkov b...@alien8.de CC: H. Peter Anvin h...@zytor.com CC: Andy Lutomirski l...@amacapital.net CC: Oleg Nesterov o...@redhat.com CC: Frederic Weisbecker fweis...@gmail.com CC: Alexei Starovoitov a...@plumgrid.com CC: Will Drewry w...@chromium.org CC: Kees Cook keesc...@chromium.org CC: x...@kernel.org CC: linux-kernel@vger.kernel.org -- 1.8.1.4 -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[PATCH 0/3] x86: do not save callee-preserved registers around lockdep_sys_exit_thunk
Recent change to struct pt_regs handling in entry.S, among other things, changed how callee-preserved registers are saved around call to lockdep_sys_exit_thunk: #define LOCKDEP_SYS_EXIT_IRQ \ TRACE_IRQS_ON; \ sti; \ SAVE_EXTRA_REGS; \<=== HERE LOCKDEP_SYS_EXIT; \ RESTORE_EXTRA_REGS; \ <=== HERE The change is in fact a bit fragile: now we assume that LOCKDEP_SYS_EXIT_IRQ macro is used only when there is a struct pt_regs on the stack. So far this assumption is true, but it is probably a coincidence. We can revert back to pushing registers, but this callee-preserved registers saving appears bogus. It is not necessary: they _are_ callee-preserved, and lockdep_sys_exit() does not touch them on the stack either. First two patches clean up #define maze so that we can see that LOCKDEP_SYS_EXIT macro call above is merely "call lockdep_sys_exit_thunk". Last patch removes SAVE/RESTORE. I tested this patch series and everything seems to run fine on a lockdep-enabled kernel with these lines removed. Denys Vlasenko (3): x86: move ARCH_LOCKDEP_SYS_EXIT[IRQ] defines closer to their users x86: fold ARCH_LOCKDEP_SYS_EXIT defines into their users x86: do not save callee-preserved registers around lockdep_sys_exit_thunk arch/x86/include/asm/irqflags.h | 45 + 1 file changed, 19 insertions(+), 26 deletions(-) CC: Linus Torvalds CC: Steven Rostedt CC: Ingo Molnar CC: Borislav Petkov CC: "H. Peter Anvin" CC: Andy Lutomirski CC: Oleg Nesterov CC: Frederic Weisbecker CC: Alexei Starovoitov CC: Will Drewry CC: Kees Cook CC: x...@kernel.org CC: linux-kernel@vger.kernel.org -- 1.8.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[PATCH 0/3] x86: do not save callee-preserved registers around lockdep_sys_exit_thunk
Recent change to struct pt_regs handling in entry.S, among other things, changed how callee-preserved registers are saved around call to lockdep_sys_exit_thunk: #define LOCKDEP_SYS_EXIT_IRQ \ TRACE_IRQS_ON; \ sti; \ SAVE_EXTRA_REGS; \=== HERE LOCKDEP_SYS_EXIT; \ RESTORE_EXTRA_REGS; \ === HERE The change is in fact a bit fragile: now we assume that LOCKDEP_SYS_EXIT_IRQ macro is used only when there is a struct pt_regs on the stack. So far this assumption is true, but it is probably a coincidence. We can revert back to pushing registers, but this callee-preserved registers saving appears bogus. It is not necessary: they _are_ callee-preserved, and lockdep_sys_exit() does not touch them on the stack either. First two patches clean up #define maze so that we can see that LOCKDEP_SYS_EXIT macro call above is merely call lockdep_sys_exit_thunk. Last patch removes SAVE/RESTORE. I tested this patch series and everything seems to run fine on a lockdep-enabled kernel with these lines removed. Denys Vlasenko (3): x86: move ARCH_LOCKDEP_SYS_EXIT[IRQ] defines closer to their users x86: fold ARCH_LOCKDEP_SYS_EXIT defines into their users x86: do not save callee-preserved registers around lockdep_sys_exit_thunk arch/x86/include/asm/irqflags.h | 45 + 1 file changed, 19 insertions(+), 26 deletions(-) CC: Linus Torvalds torva...@linux-foundation.org CC: Steven Rostedt rost...@goodmis.org CC: Ingo Molnar mi...@kernel.org CC: Borislav Petkov b...@alien8.de CC: H. Peter Anvin h...@zytor.com CC: Andy Lutomirski l...@amacapital.net CC: Oleg Nesterov o...@redhat.com CC: Frederic Weisbecker fweis...@gmail.com CC: Alexei Starovoitov a...@plumgrid.com CC: Will Drewry w...@chromium.org CC: Kees Cook keesc...@chromium.org CC: x...@kernel.org CC: linux-kernel@vger.kernel.org -- 1.8.1.4 -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
