From 309ee04257d473ce87f2c7e99f6d69e933d307e3 Mon Sep 17 00:00:00 2001 From: Russell King Date: Fri, 24 Mar 2017 16:15:45 +0000 Subject: ARM: use aliases for registers in entry-common Use aliases for the saved (and preserved) PSR and PC values so that we can control which registers are used. Signed-off-by: Russell King --- arch/arm/kernel/entry-common.S | 24 ++++++++++++++---------- 1 file changed, 14 insertions(+), 10 deletions(-) (limited to 'arch/arm/kernel/entry-common.S') diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S index eb5cd77bf1d8..9abe47a206d9 100644 --- a/arch/arm/kernel/entry-common.S +++ b/arch/arm/kernel/entry-common.S @@ -27,6 +27,8 @@ #include "entry-header.S" +saved_psr .req r8 +saved_pc .req lr .align 5 #if !(IS_ENABLED(CONFIG_TRACE_IRQFLAGS) || IS_ENABLED(CONFIG_CONTEXT_TRACKING)) @@ -141,9 +143,9 @@ ENTRY(vector_swi) ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr THUMB( mov r8, sp ) THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr - mrs r8, spsr @ called from non-FIQ mode, so ok. - str lr, [sp, #S_PC] @ Save calling PC - str r8, [sp, #S_PSR] @ Save CPSR + mrs saved_psr, spsr @ called from non-FIQ mode, so ok. + str saved_pc, [sp, #S_PC] @ Save calling PC + str saved_psr, [sp, #S_PSR] @ Save CPSR str r0, [sp, #S_OLD_R0] @ Save OLD_R0 #endif zero_fp @@ -163,11 +165,11 @@ ENTRY(vector_swi) * value to determine if it is an EABI or an old ABI call. */ #ifdef CONFIG_ARM_THUMB - tst r8, #PSR_T_BIT + tst saved_psr, #PSR_T_BIT movne r10, #0 @ no thumb OABI emulation - USER( ldreq r10, [lr, #-4] ) @ get SWI instruction + USER( ldreq r10, [saved_pc, #-4] ) @ get SWI instruction #else - USER( ldr r10, [lr, #-4] ) @ get SWI instruction + USER( ldr r10, [saved_pc, #-4] ) @ get SWI instruction #endif ARM_BE8(rev r10, r10) @ little endian instruction @@ -178,15 +180,17 @@ ENTRY(vector_swi) */ #elif defined(CONFIG_ARM_THUMB) /* Legacy ABI only, possibly thumb mode. */ - tst r8, #PSR_T_BIT @ this is SPSR from save_user_regs + tst saved_psr, #PSR_T_BIT @ this is SPSR from save_user_regs addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in - USER( ldreq scno, [lr, #-4] ) + USER( ldreq scno, [saved_pc, #-4] ) #else /* Legacy ABI only. */ - USER( ldr scno, [lr, #-4] ) @ get SWI instruction + USER( ldr scno, [saved_pc, #-4] ) @ get SWI instruction #endif + /* saved_psr and saved_pc are now dead */ + uaccess_disable tbl adr tbl, sys_call_table @ load syscall table pointer @@ -234,7 +238,7 @@ local_restart: * current task. */ 9001: - sub lr, lr, #4 + sub lr, saved_pc, #4 str lr, [sp, #S_PC] b ret_fast_syscall #endif -- cgit From da594e3fff398a164c77dd728d9fbfc6880881e6 Mon Sep 17 00:00:00 2001 From: Russell King Date: Fri, 24 Mar 2017 16:19:12 +0000 Subject: ARM: obtain thread info structure later Obtain the thread info structure later in the syscall processing, so that we free up a register for earlier code. Signed-off-by: Russell King --- arch/arm/kernel/entry-common.S | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'arch/arm/kernel/entry-common.S') diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S index 9abe47a206d9..374c28723547 100644 --- a/arch/arm/kernel/entry-common.S +++ b/arch/arm/kernel/entry-common.S @@ -152,7 +152,6 @@ ENTRY(vector_swi) alignment_trap r10, ip, __cr_alignment enable_irq ct_user_exit - get_thread_info tsk /* * Get the system call number. @@ -209,6 +208,7 @@ ENTRY(vector_swi) bic scno, scno, #0xff000000 @ mask off SWI op-code eor scno, scno, #__NR_SYSCALL_BASE @ check OS number #endif + get_thread_info tsk local_restart: ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing @@ -240,6 +240,7 @@ local_restart: 9001: sub lr, saved_pc, #4 str lr, [sp, #S_PC] + get_thread_info tsk b ret_fast_syscall #endif ENDPROC(vector_swi) -- cgit From fcea45236d3ffcd317296d75612eb163bf734407 Mon Sep 17 00:00:00 2001 From: Russell King Date: Fri, 24 Mar 2017 16:22:10 +0000 Subject: ARM: move PC value into r9 Move the saved PC value into r9, thereby moving it into a caller-saved register for functions that we may call during the entry to a syscall. Signed-off-by: Russell King --- arch/arm/kernel/entry-common.S | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'arch/arm/kernel/entry-common.S') diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S index 374c28723547..1b3fc79d0e8b 100644 --- a/arch/arm/kernel/entry-common.S +++ b/arch/arm/kernel/entry-common.S @@ -28,7 +28,13 @@ #include "entry-header.S" saved_psr .req r8 +#if defined(CONFIG_TRACE_IRQFLAGS) || defined(CONFIG_CONTEXT_TRACKING) +saved_pc .req r9 +#define TRACE(x...) x +#else saved_pc .req lr +#define TRACE(x...) +#endif .align 5 #if !(IS_ENABLED(CONFIG_TRACE_IRQFLAGS) || IS_ENABLED(CONFIG_CONTEXT_TRACKING)) @@ -144,6 +150,7 @@ ENTRY(vector_swi) THUMB( mov r8, sp ) THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr mrs saved_psr, spsr @ called from non-FIQ mode, so ok. + TRACE( mov saved_pc, lr ) str saved_pc, [sp, #S_PC] @ Save calling PC str saved_psr, [sp, #S_PSR] @ Save CPSR str r0, [sp, #S_OLD_R0] @ Save OLD_R0 -- cgit From dca778c5bbf3f1cfcf7f6ef6cadf5a7e5c5d972f Mon Sep 17 00:00:00 2001 From: Russell King Date: Fri, 24 Mar 2017 16:23:25 +0000 Subject: ARM: avoid saving and restoring registers unnecessarily Avoid repeatedly saving and restoring registers around the calls to trace_hardirqs_on() and context_tracking_user_exit(). With the previous changes, we no longer need to preserve "lr" across these calls, and if we re-load r0-r3 later, we can avoid preserving these regsiters too. Signed-off-by: Russell King --- arch/arm/kernel/entry-common.S | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) (limited to 'arch/arm/kernel/entry-common.S') diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S index 1b3fc79d0e8b..0b60adf4a5d9 100644 --- a/arch/arm/kernel/entry-common.S +++ b/arch/arm/kernel/entry-common.S @@ -157,8 +157,9 @@ ENTRY(vector_swi) #endif zero_fp alignment_trap r10, ip, __cr_alignment - enable_irq - ct_user_exit + asm_trace_hardirqs_on save=0 + enable_irq_notrace + ct_user_exit save=0 /* * Get the system call number. @@ -216,6 +217,11 @@ ENTRY(vector_swi) eor scno, scno, #__NR_SYSCALL_BASE @ check OS number #endif get_thread_info tsk + /* + * Reload the registers that may have been corrupted on entry to + * the syscall assembly (by tracing or context tracking.) + */ + TRACE( ldmia sp, {r0 - r3} ) local_restart: ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing -- cgit