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[debugserver] This is a small cleanup patch to AVX support detection 

Summary:
The first Sandybridge iMacs with AVX support shipped in Spring 2011 with Snow Leopard as their OS. Unfortunately due to a kernel bug debugging AVX code was not really possible until 10.7.4.

The old code here checked the kernel build number to determine when to support AVX, but that code was incorrect. It verified that the kernel build number was greater than xnu-2020, which is the build of the kernel that had the fix for 10.8. The fix was also back ported to 10.7.4. Which means all publicly available OS builds 10.7.4 and later have working AVX support.

This new patch verifies that the host OS is greater than or equal to 10.7.4 by checking that the build number is greater than or equal to 11Exx.

The patch also removes the HasAVX assembly blob in favor of querying the kernel via sysctl for the hardware features.

Using sysctl is slower, however since the code is executed once and the result cached it is a better approach because it is possible for the kernel to disable AVX support on hardware that supports it, so listening to the kernel is a better approach for the debugger to take.

Reviewers: jasonmolenda, spyffe

Subscribers: lldb-commits, mgorny

Differential Revision: https://reviews.llvm.org/D30918

llvm-svn: 297685
This commit is contained in:
Chris Bieneman 2017-03-13 23:19:04 +00:00
parent 19aadf57c8
commit 1899e8d9e8
6 changed files with 53 additions and 119 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
lldb/tools/debugserver/debugserver.xcodeproj/project.pbxproj
View File

@ -94,10 +94,8 @@
456F67641AD46CE9002850C2 /* CFBundle.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 2695DD910D3EBFF6007E4CA2 /* CFBundle.cpp */; };
456F67651AD46CE9002850C2 /* PseudoTerminal.cpp in Sources */ = {isa = PBXBuildFile; fileRef = AF67ABFF0D34604D0022D128 /* PseudoTerminal.cpp */; };
456F67671AD46CE9002850C2 /* DNBArch.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 264D5D571293835600ED4C01 /* DNBArch.cpp */; };
456F67681AD46CE9002850C2 /* HasAVX.s in Sources */ = {isa = PBXBuildFile; fileRef = 4971AE7113D10F4F00649E37 /* HasAVX.s */; };
456F67691AD46CE9002850C2 /* DNBArchImplARM64.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 266B5ECF1460A68200E43F0A /* DNBArchImplARM64.cpp */; };
456F676B1AD46CE9002850C2 /* CoreFoundation.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 26ACA3340D3E956300A2120B /* CoreFoundation.framework */; settings = {ATTRIBUTES = (Required, ); }; };
4971AE7213D10F4F00649E37 /* HasAVX.s in Sources */ = {isa = PBXBuildFile; fileRef = 4971AE7113D10F4F00649E37 /* HasAVX.s */; };
49D404621E39260F00570CDC /* Foundation.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 49D404611E39260F00570CDC /* Foundation.framework */; };
AF48558C1D75126800D19C07 /* StdStringExtractor.cpp in Sources */ = {isa = PBXBuildFile; fileRef = AF48558B1D75126800D19C07 /* StdStringExtractor.cpp */; };
AF48558D1D75127500D19C07 /* StdStringExtractor.cpp in Sources */ = {isa = PBXBuildFile; fileRef = AF48558B1D75126800D19C07 /* StdStringExtractor.cpp */; };
@ -210,8 +208,6 @@
26CF99A31142EB7400011AAB /* DNBArchImplX86_64.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = DNBArchImplX86_64.h; sourceTree = "<group>"; };
26E6B9DA0D1329010037ECDD /* RNBDefs.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = RNBDefs.h; sourceTree = "<group>"; };
456F67721AD46CE9002850C2 /* debugserver-nonui */ = {isa = PBXFileReference; explicitFileType = "compiled.mach-o.executable"; includeInIndex = 0; path = "debugserver-nonui"; sourceTree = BUILT_PRODUCTS_DIR; };
4971AE7013D10F4F00649E37 /* HasAVX.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = HasAVX.h; sourceTree = "<group>"; };
4971AE7113D10F4F00649E37 /* HasAVX.s */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.asm; path = HasAVX.s; sourceTree = "<group>"; };
49D404611E39260F00570CDC /* Foundation.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = Foundation.framework; path = System/Library/Frameworks/Foundation.framework; sourceTree = SDKROOT; };
49F530111331519C008956F6 /* MachRegisterStatesI386.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = MachRegisterStatesI386.h; sourceTree = "<group>"; };
49F5301213316D7F008956F6 /* MachRegisterStatesX86_64.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = MachRegisterStatesX86_64.h; sourceTree = "<group>"; };
@ -413,8 +409,6 @@
26C637E90C71334A0024798E /* i386 */,
26C637FA0C71334A0024798E /* ppc */,
26CF99A11142EB7400011AAB /* x86_64 */,
4971AE7013D10F4F00649E37 /* HasAVX.h */,
4971AE7113D10F4F00649E37 /* HasAVX.s */,
26C637E80C71334A0024798E /* dbgnub-mig.defs */,
AFEC3363194A8B0B00FF05C6 /* Genealogy.cpp */,
AF0934BA18E12B92005A11FD /* Genealogy.h */,
@ -626,7 +620,6 @@
23562ED91D342B0000AB2BD4 /* LogMessage.cpp in Sources */,
26CE05F1115C387C0022F371 /* PseudoTerminal.cpp in Sources */,
264D5D581293835600ED4C01 /* DNBArch.cpp in Sources */,
4971AE7213D10F4F00649E37 /* HasAVX.s in Sources */,
237821B01D4917D20028B7A1 /* LogFilterExactMatch.cpp in Sources */,
266B5ED11460A68200E43F0A /* DNBArchImplARM64.cpp in Sources */,
);
@ -679,7 +672,6 @@
456F67641AD46CE9002850C2 /* CFBundle.cpp in Sources */,
456F67651AD46CE9002850C2 /* PseudoTerminal.cpp in Sources */,
456F67671AD46CE9002850C2 /* DNBArch.cpp in Sources */,
456F67681AD46CE9002850C2 /* HasAVX.s in Sources */,
23AC04D01D2F58AF0072351D /* LogFilterRegex.cpp in Sources */,
456F67691AD46CE9002850C2 /* DNBArchImplARM64.cpp in Sources */,
);

1
lldb/tools/debugserver/source/MacOSX/CMakeLists.txt
View File

@ -29,7 +29,6 @@ add_custom_command(OUTPUT ${DEBUGSERVER_VERS_GENERATED_FILE}
)
add_lldb_tool(debugserver INCLUDE_IN_FRAMEWORK
HasAVX.s
CFBundle.cpp
CFString.cpp
Genealogy.cpp

27
lldb/tools/debugserver/source/MacOSX/HasAVX.h
View File

@ -1,27 +0,0 @@
//===-- HasAVX.h ------------------------------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#ifndef HasAVX_h
#define HasAVX_h
#if defined(__i386__) || defined(__x86_64__)
#ifdef __cplusplus
extern "C" {
#endif
int HasAVX();
#ifdef __cplusplus
}
#endif
#endif
#endif

50
lldb/tools/debugserver/source/MacOSX/HasAVX.s
View File

@ -1,50 +0,0 @@
//===-- HasAVX.s ---------------------------------------*- x86 Assembly -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#if defined (__i386__) || defined (__x86_64__)
.globl _HasAVX
_HasAVX:
#if defined (__x86_64__)
pushq %rbp
movq %rsp, %rbp
pushq %rbx
#else
pushl %ebp
movl %esp, %ebp
pushl %ebx
#endif
mov $1, %eax
cpuid // clobbers ebx
and $0x018000000, %ecx
cmp $0x018000000, %ecx
jne not_supported
mov $0, %ecx
.byte 0x0f, 0x01, 0xd0 // xgetbv, for those assemblers that don't know it
and $0x06, %eax
cmp $0x06, %eax
jne not_supported
mov $1, %eax
jmp done
not_supported:
mov $0, %eax
done:
#if defined (__x86_64__)
popq %rbx
movq %rbp, %rsp
popq %rbp
#else
popl %ebx
movl %ebp, %esp
popl %ebp
#endif
ret // return
#endif

1
lldb/tools/debugserver/source/MacOSX/i386/DNBArchImplI386.h
View File

@ -16,7 +16,6 @@
#if defined(__i386__) || defined(__x86_64__)
#include "../HasAVX.h"
#include "DNBArch.h"
#include "MachRegisterStatesI386.h"

77
lldb/tools/debugserver/source/MacOSX/x86_64/DNBArchImplX86_64.cpp
View File

@ -17,7 +17,6 @@
#include <sys/sysctl.h>
#include <sys/types.h>
#include "../HasAVX.h"
#include "DNBLog.h"
#include "MacOSX/x86_64/DNBArchImplX86_64.h"
#include "MachProcess.h"
@ -60,42 +59,64 @@ static bool ForceAVXRegs() {
#define FORCE_AVX_REGS (0)
#endif
extern "C" bool CPUHasAVX() {
enum AVXPresence { eAVXUnknown = -1, eAVXNotPresent = 0, eAVXPresent = 1 };
bool DetectHardwareFeature(const char *feature) {
int answer = 0;
size_t answer_size = sizeof(answer);
int error = ::sysctlbyname(feature, &answer, &answer_size, NULL, 0);
return error != 0 && answer != 0;
}
enum AVXPresence { eAVXUnknown = -1, eAVXNotPresent = 0, eAVXPresent = 1 };
bool LogAVXAndReturn(AVXPresence has_avx, int err, const char * os_ver) {
DNBLogThreadedIf(LOG_THREAD,
"CPUHasAVX(): g_has_avx = %i (err = %i, os_ver = %s)",
has_avx, err, os_ver);
return (has_avx == eAVXPresent);
}
extern "C" bool CPUHasAVX() {
static AVXPresence g_has_avx = eAVXUnknown;
if (g_has_avx == eAVXUnknown) {
if (g_has_avx != eAVXUnknown)
return LogAVXAndReturn(g_has_avx, 0, "");
g_has_avx = eAVXNotPresent;
// Only xnu-2020 or later has AVX support, any versions before
// this have a busted thread_get_state RPC where it would truncate
// the thread state buffer (<rdar://problem/10122874>). So we need to
// verify the kernel version number manually or disable AVX support.
// OS X 10.7.3 and earlier have a bug in thread_get_state that truncated the
// size of the return. To work around this we have to disable AVX debugging
// on hosts prior to 10.7.3 (<rdar://problem/10122874>).
int mib[2];
char buffer[1024];
size_t length = sizeof(buffer);
uint64_t xnu_version = 0;
mib[0] = CTL_KERN;
mib[1] = KERN_VERSION;
int err = ::sysctl(mib, 2, &buffer, &length, NULL, 0);
if (err == 0) {
const char *xnu = strstr(buffer, "xnu-");
if (xnu) {
const char *xnu_version_cstr = xnu + 4;
xnu_version = strtoull(xnu_version_cstr, NULL, 0);
if (xnu_version >= 2020 && xnu_version != ULLONG_MAX) {
if (::HasAVX()) {
g_has_avx = eAVXPresent;
}
}
}
}
DNBLogThreadedIf(LOG_THREAD, "CPUHasAVX(): g_has_avx = %i (err = %i, errno "
"= %i, xnu_version = %llu)",
g_has_avx, err, errno, xnu_version);
}
mib[1] = KERN_OSVERSION;
return (g_has_avx == eAVXPresent);
// KERN_OSVERSION returns the build number which is a number signifying the
// major version, a capitol letter signifying the minor version, and numbers
// signifying the build (ex: on 10.12.3, the returned value is 16D32).
int err = ::sysctl(mib, 2, &buffer, &length, NULL, 0);
if (err != 0)
return LogAVXAndReturn(g_has_avx, err, "");
size_t first_letter = 0;
for (; first_letter < length; ++first_letter) {
// This is looking for the first uppercase letter
if (isupper(buffer[first_letter]))
break;
}
char letter = buffer[first_letter];
buffer[first_letter] = '\0';
auto major_ver = strtoull(buffer, NULL, 0);
buffer[first_letter] = letter;
// In this check we're looking to see that our major and minor version numer
// was >= 11E, which is the 10.7.4 release.
if (major_ver < 11 || (major_ver == 11 && letter < 'E'))
return LogAVXAndReturn(g_has_avx, err, buffer);
if (DetectHardwareFeature("hw.optional.avx1_0"))
g_has_avx = eAVXPresent;
return LogAVXAndReturn(g_has_avx, err, buffer);
}
uint64_t DNBArchImplX86_64::GetPC(uint64_t failValue) {