Date: Sun, 16 Oct 2011 17:59:28 +0000 (UTC) From: Olivier Houchard <cognet@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r226443 - head/sys/arm/include Message-ID: <201110161759.p9GHxSsC073442@svn.freebsd.org>
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Author: cognet Date: Sun Oct 16 17:59:28 2011 New Revision: 226443 URL: http://svn.freebsd.org/changeset/base/226443 Log: Fix 2 bugs : - A race condition could happen if two threads were using RAS at the same time as the code didn't reset RAS_END, the RAS code could believe we were not in a RAS, when we were in fact. - Using signed value logic to compare addresses wasn't such a good idea. Many thanks to Ian to investigate on these issues. Pointy hat to: cognet PR: arm/161498 Submitted by: Ian Lepore <freebsd At damnhippie DOT dyndns dot org MFC after: 1 week Modified: head/sys/arm/include/asmacros.h head/sys/arm/include/sysarch.h Modified: head/sys/arm/include/asmacros.h ============================================================================== --- head/sys/arm/include/asmacros.h Sun Oct 16 17:38:20 2011 (r226442) +++ head/sys/arm/include/asmacros.h Sun Oct 16 17:59:28 2011 (r226443) @@ -71,9 +71,8 @@ ldr r0, =ARM_RAS_START; \ mov r1, #0; \ str r1, [r0]; \ - ldr r0, =ARM_RAS_END; \ mov r1, #0xffffffff; \ - str r1, [r0]; + str r1, [r0, #4]; /* * PULLFRAME - macro to pull a trap frame from the stack in the current mode @@ -120,20 +119,19 @@ stmia r0, {r13-r14}^; /* Push the user mode registers */ \ mov r0, r0; /* NOP for previous instruction */ \ ldr r5, =ARM_RAS_START; /* Check if there's any RAS */ \ - ldr r3, [r5]; \ - cmp r3, #0; /* Is the update needed ? */ \ - ldrgt lr, [r0, #16]; \ - ldrgt r1, =ARM_RAS_END; \ - ldrgt r4, [r1]; /* Get the end of the RAS */ \ - movgt r2, #0; /* Reset the magic addresses */ \ - strgt r2, [r5]; \ - movgt r2, #0xffffffff; \ - strgt r2, [r1]; \ - cmpgt lr, r3; /* Were we in the RAS ? */ \ - cmpgt r4, lr; \ - strgt r3, [r0, #16]; /* Yes, update the pc */ \ - mrs r0, spsr_all; /* Put the SPSR on the stack */ \ - str r0, [sp, #-4]! + ldr r4, [r5, #4]; /* reset it to point at the */ \ + cmp r4, #0xffffffff; /* end of memory if necessary; */ \ + movne r1, #0xffffffff; /* leave value in r4 for later */ \ + strne r1, [r5, #4]; /* comparision against PC. */ \ + ldr r3, [r5]; /* Retrieve global RAS_START */ \ + cmp r3, #0; /* and reset it if non-zero. */ \ + movne r1, #0; /* If non-zero RAS_START and */ \ + strne r1, [r5]; /* PC was lower than RAS_END, */ \ + ldrne r1, [r0, #16]; /* adjust the saved PC so that */ \ + cmpne r4, r1; /* execution later resumes at */ \ + strhi r3, [r0, #16]; /* the RAS_START location. */ \ + mrs r0, spsr_all; \ + str r0, [sp, #-4]! /* * PULLFRAMEFROMSVCANDEXIT - macro to pull a trap frame from the stack Modified: head/sys/arm/include/sysarch.h ============================================================================== --- head/sys/arm/include/sysarch.h Sun Oct 16 17:38:20 2011 (r226442) +++ head/sys/arm/include/sysarch.h Sun Oct 16 17:59:28 2011 (r226443) @@ -42,9 +42,13 @@ * The ARM_TP_ADDRESS points to a special purpose page, which is used as local * store for the ARM per-thread data and Restartable Atomic Sequences support. * Put it just above the "high" vectors' page. - * the cpu_switch() code assumes ARM_RAS_START is ARM_TP_ADDRESS + 4, and + * The cpu_switch() code assumes ARM_RAS_START is ARM_TP_ADDRESS + 4, and * ARM_RAS_END is ARM_TP_ADDRESS + 8, so if that ever changes, be sure to * update the cpu_switch() (and cpu_throw()) code as well. + * In addition, code in arm/include/atomic.h and arm/include/asmacros.h + * assumes that ARM_RAS_END is at ARM_RAS_START+4, so be sure to update those + * if ARM_RAS_END moves in relation to ARM_RAS_START (look for occurrances + * of ldr/str rm,[rn, #4]). */ #define ARM_TP_ADDRESS (ARM_VECTORS_HIGH + 0x1000) #define ARM_RAS_START (ARM_TP_ADDRESS + 4)
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