On Thu, May 30, 2013 at 10:09:49AM +0100, Will Deacon wrote: > On Thu, May 30, 2013 at 02:41:42AM +0100, Wang, Yalin wrote: > > If you have some patch for this issue, > > I can do the test for it . > > I'll have a look at cooking something which uses an exception table entry > to rewind the PC and retry the system call. That's simpler than directly > injecting a user page fault from the system call path. Ok, please can you try the following? Will --->8 diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S index bc5bc0a..855926e 100644 --- a/arch/arm/kernel/entry-common.S +++ b/arch/arm/kernel/entry-common.S @@ -361,6 +361,15 @@ ENTRY(vector_swi) str r8, [sp, #S_PSR] @ Save CPSR str r0, [sp, #S_OLD_R0] @ Save OLD_R0 zero_fp + enable_irq + ct_user_exit + +#ifdef CONFIG_ALIGNMENT_TRAP + ldr ip, __cr_alignment + ldr ip, [ip] + mcr p15, 0, ip, c1, c0 @ update control register +#endif + get_thread_info tsk /* * Get the system call number. @@ -375,9 +384,9 @@ ENTRY(vector_swi) #ifdef CONFIG_ARM_THUMB tst r8, #PSR_T_BIT movne r10, #0 @ no thumb OABI emulation - ldreq r10, [lr, #-4] @ get SWI instruction + USER( ldreq r10, [lr, #-4] ) @ get SWI instruction #else - ldr r10, [lr, #-4] @ get SWI instruction + USER( ldr r10, [lr, #-4] ) @ get SWI instruction #endif #ifdef CONFIG_CPU_ENDIAN_BE8 rev r10, r10 @ little endian instruction @@ -392,22 +401,13 @@ ENTRY(vector_swi) /* Legacy ABI only, possibly thumb mode. */ tst r8, #PSR_T_BIT @ this is SPSR from save_user_regs addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in - ldreq scno, [lr, #-4] + USER( ldreq scno, [lr, #-4] ) #else /* Legacy ABI only. */ - ldr scno, [lr, #-4] @ get SWI instruction -#endif - -#ifdef CONFIG_ALIGNMENT_TRAP - ldr ip, __cr_alignment - ldr ip, [ip] - mcr p15, 0, ip, c1, c0 @ update control register + USER( ldr scno, [lr, #-4] ) @ get SWI instruction #endif - enable_irq - ct_user_exit - get_thread_info tsk adr tbl, sys_call_table @ load syscall table pointer #if defined(CONFIG_OABI_COMPAT) @@ -442,6 +442,18 @@ local_restart: eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back bcs arm_syscall b sys_ni_syscall @ not private func + +#if defined(CONFIG_OABI_COMPAT) || !defined(CONFIG_AEABI) + /* + * We may have faulted trying to load the SWI instruction due to + * concurrent page aging on another CPU. In this case, return + * back to the swi instruction and fault the page back. + */ +9001: + sub lr, lr, #4 + str lr, [sp, #S_PC] + b ret_fast_syscall +#endif ENDPROC(vector_swi) /* -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
