Date: Wed, 23 Sep 2020 00:09:29 +0000 (UTC) From: Brandon Bergren <bdragon@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r366037 - in head/sys: conf powerpc/conf powerpc/ofw powerpc/powernv Message-ID: <202009230009.08N09ThC016444@repo.freebsd.org>
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Author: bdragon Date: Wed Sep 23 00:09:29 2020 New Revision: 366037 URL: https://svnweb.freebsd.org/changeset/base/366037 Log: [PowerPC64LE] Work around qemu TCG bug in mtmsrd emulation. The TCG implementation of mtmsrd in qemu blindly copies the entire register to the MSR, instead of the specific bit positions listed in the ISA. This means that qemu will prematurely switch endian out from under the running code instead of waiting for the rfid, causing an immediate trap as it attempts to interpret the next instruction in the wrong endianness. To work around this, ensure PSL_LE is still set before doing the mtmsrd. In the future, we may wish to just turn off translation and unconditionally use rfid to switch to the ofmsr instead of quasi-switching to the ofmsr. Add a new platform option so this can be disabled. (And so that we can conditonalize additional QEMU-specific hacks in the platform code.) Sponsored by: Tag1 Consulting, Inc. Modified: head/sys/conf/options.powerpc head/sys/powerpc/conf/GENERIC64 head/sys/powerpc/conf/NOTES head/sys/powerpc/ofw/ofwcall64.S head/sys/powerpc/powernv/opalcall.S Modified: head/sys/conf/options.powerpc ============================================================================== --- head/sys/conf/options.powerpc Wed Sep 23 00:06:48 2020 (r366036) +++ head/sys/conf/options.powerpc Wed Sep 23 00:09:29 2020 (r366037) @@ -29,6 +29,7 @@ MAMBO POWERNV opt_platform.h PSERIES PSIM +QEMU opt_platform.h SC_OFWFB opt_ofwfb.h Modified: head/sys/powerpc/conf/GENERIC64 ============================================================================== --- head/sys/powerpc/conf/GENERIC64 Wed Sep 23 00:06:48 2020 (r366036) +++ head/sys/powerpc/conf/GENERIC64 Wed Sep 23 00:09:29 2020 (r366037) @@ -30,6 +30,7 @@ makeoptions WITH_CTF=1 options POWERMAC #NewWorld Apple PowerMacs options PS3 #Sony Playstation 3 options MAMBO #IBM Mambo Full System Simulator +options QEMU #QEMU processor emulator options PSERIES #PAPR-compliant systems (e.g. IBM p) options POWERNV #Non-virtualized OpenPOWER systems Modified: head/sys/powerpc/conf/NOTES ============================================================================== --- head/sys/powerpc/conf/NOTES Wed Sep 23 00:06:48 2020 (r366036) +++ head/sys/powerpc/conf/NOTES Wed Sep 23 00:09:29 2020 (r366037) @@ -44,6 +44,7 @@ options POWERMAC #NewWorld Apple PowerMacs #options PS3 #Sony Playstation 3 options PSIM #GDB PSIM ppc simulator options MAMBO #IBM Mambo Full System Simulator +options QEMU #QEMU processor emulator # The cpufreq(4) driver provides support for CPU frequency control device cpufreq Modified: head/sys/powerpc/ofw/ofwcall64.S ============================================================================== --- head/sys/powerpc/ofw/ofwcall64.S Wed Sep 23 00:06:48 2020 (r366036) +++ head/sys/powerpc/ofw/ofwcall64.S Wed Sep 23 00:09:29 2020 (r366037) @@ -32,6 +32,8 @@ #include <machine/spr.h> #include <machine/asm.h> +#include "opt_platform.h" + #define OFWSTKSZ 4096 /* 4K Open Firmware stack */ /* @@ -119,6 +121,10 @@ ASENTRY_NOPROF(ofwcall) addis %r5,%r2,TOC_REF(ofmsr)@ha ld %r5,TOC_REF(ofmsr)@l(%r5) ld %r5,0(%r5) +#if defined(__LITTLE_ENDIAN__) && defined(QEMU) + /* QEMU hack: qemu does not emulate mtmsrd correctly! */ + ori %r5,%r5,1 /* Leave PSR_LE set */ +#endif mtmsrd %r5 isync @@ -270,6 +276,10 @@ ASENTRY_NOPROF(rtascall) addis %r7,%r2,TOC_REF(rtasmsr)@ha ld %r7,TOC_REF(rtasmsr)@l(%r7) ld %r7,0(%r7) +#ifdef __LITTLE_ENDIAN__ + /* QEMU hack: qemu does not emulate mtmsrd correctly! */ + ori %r7,%r7,1 /* Leave PSR_LE set */ +#endif mtmsrd %r7 isync Modified: head/sys/powerpc/powernv/opalcall.S ============================================================================== --- head/sys/powerpc/powernv/opalcall.S Wed Sep 23 00:06:48 2020 (r366036) +++ head/sys/powerpc/powernv/opalcall.S Wed Sep 23 00:09:29 2020 (r366037) @@ -27,6 +27,8 @@ #include <machine/asm.h> +#include "opt_platform.h" + GLOBAL(opal_entrypoint) .llong 0 GLOBAL(opal_data) @@ -70,8 +72,17 @@ ASENTRY(opal_call) ld %r2,TOC_REF(opal_data)@l(%r2) ld %r2,0(%r2) + +#if defined(__LITTLE_ENDIAN__) && defined(QEMU) + /* QEMU hack: qemu does not emulate mtmsrd correctly! */ + ori %r3,%r3,1 /* Leave PSR_LE set */ +#endif mtmsrd %r3 isync +#if defined(__LITTLE_ENDIAN__) && defined(QEMU) + /* Clean up from qemu hack */ + xori %r3,%r3,1 +#endif /* Shift registers over */ mr %r3,%r4
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