From 4dcc29e1574d88f4465ba865ed82800032f76418 Mon Sep 17 00:00:00 2001 From: Tony Luck Date: Tue, 27 May 2008 13:23:16 -0700 Subject: [IA64] Workaround for RSE issue Problem: An application violating the architectural rules regarding operation dependencies and having specific Register Stack Engine (RSE) state at the time of the violation, may result in an illegal operation fault and invalid RSE state. Such faults may initiate a cascade of repeated illegal operation faults within OS interruption handlers. The specific behavior is OS dependent. Implication: An application causing an illegal operation fault with specific RSE state may result in a series of illegal operation faults and an eventual OS stack overflow condition. Workaround: OS interruption handlers that switch to kernel backing store implement a check for invalid RSE state to avoid the series of illegal operation faults. The core of the workaround is the RSE_WORKAROUND code sequence inserted into each invocation of the SAVE_MIN_WITH_COVER and SAVE_MIN_WITH_COVER_R19 macros. This sequence includes hard-coded constants that depend on the number of stacked physical registers being 96. The rest of this patch consists of code to disable this workaround should this not be the case (with the presumption that if a future Itanium processor increases the number of registers, it would also remove the need for this patch). Move the start of the RBS up to a mod32 boundary to avoid some corner cases. The dispatch_illegal_op_fault code outgrew the spot it was squatting in when built with this patch and CONFIG_VIRT_CPU_ACCOUNTING=y Move it out to the end of the ivt. Signed-off-by: Tony Luck --- arch/ia64/kernel/ivt.S | 84 +++++++++++++++++++++++++------------------------- 1 file changed, 42 insertions(+), 42 deletions(-) (limited to 'arch/ia64/kernel/ivt.S') diff --git a/arch/ia64/kernel/ivt.S b/arch/ia64/kernel/ivt.S index 6678c49daba3..80b44ea052d7 100644 --- a/arch/ia64/kernel/ivt.S +++ b/arch/ia64/kernel/ivt.S @@ -1076,48 +1076,6 @@ END(ia64_syscall_setup) DBG_FAULT(15) FAULT(15) - /* - * Squatting in this space ... - * - * This special case dispatcher for illegal operation faults allows preserved - * registers to be modified through a callback function (asm only) that is handed - * back from the fault handler in r8. Up to three arguments can be passed to the - * callback function by returning an aggregate with the callback as its first - * element, followed by the arguments. - */ -ENTRY(dispatch_illegal_op_fault) - .prologue - .body - SAVE_MIN_WITH_COVER - ssm psr.ic | PSR_DEFAULT_BITS - ;; - srlz.i // guarantee that interruption collection is on - ;; -(p15) ssm psr.i // restore psr.i - adds r3=8,r2 // set up second base pointer for SAVE_REST - ;; - alloc r14=ar.pfs,0,0,1,0 // must be first in insn group - mov out0=ar.ec - ;; - SAVE_REST - PT_REGS_UNWIND_INFO(0) - ;; - br.call.sptk.many rp=ia64_illegal_op_fault -.ret0: ;; - alloc r14=ar.pfs,0,0,3,0 // must be first in insn group - mov out0=r9 - mov out1=r10 - mov out2=r11 - movl r15=ia64_leave_kernel - ;; - mov rp=r15 - mov b6=r8 - ;; - cmp.ne p6,p0=0,r8 -(p6) br.call.dpnt.many b6=b6 // call returns to ia64_leave_kernel - br.sptk.many ia64_leave_kernel -END(dispatch_illegal_op_fault) - .org ia64_ivt+0x4000 ///////////////////////////////////////////////////////////////////////////////////////// // 0x4000 Entry 16 (size 64 bundles) Reserved @@ -1715,6 +1673,48 @@ END(ia32_interrupt) DBG_FAULT(67) FAULT(67) + /* + * Squatting in this space ... + * + * This special case dispatcher for illegal operation faults allows preserved + * registers to be modified through a callback function (asm only) that is handed + * back from the fault handler in r8. Up to three arguments can be passed to the + * callback function by returning an aggregate with the callback as its first + * element, followed by the arguments. + */ +ENTRY(dispatch_illegal_op_fault) + .prologue + .body + SAVE_MIN_WITH_COVER + ssm psr.ic | PSR_DEFAULT_BITS + ;; + srlz.i // guarantee that interruption collection is on + ;; +(p15) ssm psr.i // restore psr.i + adds r3=8,r2 // set up second base pointer for SAVE_REST + ;; + alloc r14=ar.pfs,0,0,1,0 // must be first in insn group + mov out0=ar.ec + ;; + SAVE_REST + PT_REGS_UNWIND_INFO(0) + ;; + br.call.sptk.many rp=ia64_illegal_op_fault +.ret0: ;; + alloc r14=ar.pfs,0,0,3,0 // must be first in insn group + mov out0=r9 + mov out1=r10 + mov out2=r11 + movl r15=ia64_leave_kernel + ;; + mov rp=r15 + mov b6=r8 + ;; + cmp.ne p6,p0=0,r8 +(p6) br.call.dpnt.many b6=b6 // call returns to ia64_leave_kernel + br.sptk.many ia64_leave_kernel +END(dispatch_illegal_op_fault) + #ifdef CONFIG_IA32_SUPPORT /* -- cgit v1.2.3