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Add guarded virtual memory support for z/OS #8279

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9 changes: 9 additions & 0 deletions gc/base/MemoryManager.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -80,6 +80,15 @@ MM_MemoryManager::createVirtualMemoryForHeap(MM_EnvironmentBase *env, MM_MemoryH

uintptr_t allocateSize = size;

/*
* Guard heap memory for Balanced.
* This feature is supported on ZOS only.
* Guarding object heap and sparse heap is necessary to not exceed MEMLIMIT.
*/
if (extensions->isVLHGC()) {
mode |= OMRPORT_VMEM_MEMORY_MODE_GUARDED;
}

uintptr_t concurrentScavengerPageSize = 0;
if (extensions->isConcurrentScavengerHWSupported()) {
OMRPORT_ACCESS_FROM_ENVIRONMENT(env);
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2 changes: 1 addition & 1 deletion gc/base/SparseVirtualMemory.hpp
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Expand Up @@ -87,7 +87,7 @@ class MM_SparseVirtualMemory : public MM_VirtualMemory {
MM_SparseVirtualMemory(MM_EnvironmentBase *env, uintptr_t pageSize, uintptr_t pageFlags, MM_Heap *in_heap)
: MM_VirtualMemory(
env, in_heap->getHeapRegionManager()->getRegionSize(), pageSize, pageFlags, 0,
OMRPORT_VMEM_MEMORY_MODE_READ | OMRPORT_VMEM_MEMORY_MODE_WRITE | OMRPORT_VMEM_MEMORY_MODE_VIRTUAL)
OMRPORT_VMEM_MEMORY_MODE_READ | OMRPORT_VMEM_MEMORY_MODE_WRITE | OMRPORT_VMEM_MEMORY_MODE_VIRTUAL | OMRPORT_VMEM_MEMORY_MODE_GUARDED)
, _heap(in_heap)
, _sparseDataPool(NULL)
, _largeObjectVirtualMemoryMutex(NULL)
Expand Down
1 change: 1 addition & 0 deletions include_core/omrport.h
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Expand Up @@ -235,6 +235,7 @@
#define OMRPORT_VMEM_ALLOCATE_TOP_DOWN 0x00000020
#define OMRPORT_VMEM_ALLOCATE_PERSIST 0x00000040
#define OMRPORT_VMEM_NO_AFFINITY 0x00000080
#define OMRPORT_VMEM_MEMORY_MODE_GUARDED 0x00000100
/** @} */

/**
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211 changes: 210 additions & 1 deletion port/zos390/omriarv64.c
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Expand Up @@ -153,6 +153,61 @@ void * omrallocate_1M_pageable_pages_above_bar(int *numMBSegments, int *userExte
return (void *)origin;
}

#pragma prolog(omrallocate_1M_pageable_pages_guarded_above_bar,"MYPROLOG")
#pragma epilog(omrallocate_1M_pageable_pages_guarded_above_bar,"MYEPILOG")

__asm(" IARV64 PLISTVER=MAX,MF=(L,SGETSTOR)":"DS"(sgetstor));

/*
* Allocate 1MB pageable guarded pages above 2GB bar using IARV64 system macro.
* Memory allocated is freed using omrfree_memory_above_bar().
*
* @params[in] numMBSegments Number of 1MB segments to be allocated
* @params[in] userExtendedPrivateAreaMemoryType capability of OS: 0 - general, 1 - 2G-32G range, 2 - 2G-64G range
*
* @return pointer to memory allocated, NULL on failure.
*/
void *omrallocate_1M_pageable_pages_guarded_above_bar(int *numMBSegments, int *userExtendedPrivateAreaMemoryType, const char *ttkn) {
long segments;
long origin;

@joransiu joransiu Jun 23, 2026

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We should initialize these variables with a default value.

long useMemoryType = *userExtendedPrivateAreaMemoryType;
int iarv64_rc = 0;

__asm(" IARV64 PLISTVER=MAX,MF=(L,SGETSTOR)":"DS"(wgetstor));

segments = *numMBSegments;
wgetstor = ngetstor;

@joransiu joransiu Jun 23, 2026

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The ngetstor should be referencing the sgetstor you declared globally for this function.


switch (useMemoryType) {
case ZOS64_VMEM_ABOVE_BAR_GENERAL:
__asm(" IARV64 REQUEST=GETSTOR,COND=YES,SADMP=NO,CONTROL=UNAUTH,"\
"GUARDSIZE64=(%2),"\
"PAGEFRAMESIZE=PAGEABLE1MEG,TYPE=PAGEABLE,SEGMENTS=(%2),"\
"ORIGIN=(%1),TTOKEN=(%4),RETCODE=%0,MF=(E,(%3))"\
::"m"(iarv64_rc),"r"(&origin),"r"(&segments),"r"(&wgetstor),"r"(ttkn));
break;
case ZOS64_VMEM_2_TO_32G:
__asm(" IARV64 REQUEST=GETSTOR,COND=YES,SADMP=NO,CONTROL=UNAUTH,USE2GTO32G=YES,"\
"GUARDSIZE64=(%2),"\
"PAGEFRAMESIZE=PAGEABLE1MEG,TYPE=PAGEABLE,SEGMENTS=(%2),"\
"ORIGIN=(%1),TTOKEN=(%4),RETCODE=%0,MF=(E,(%3))"\
::"m"(iarv64_rc),"r"(&origin),"r"(&segments),"r"(&wgetstor),"r"(ttkn));
break;
case ZOS64_VMEM_2_TO_64G:
__asm(" IARV64 REQUEST=GETSTOR,COND=YES,SADMP=NO,CONTROL=UNAUTH,USE2GTO64G=YES,"\
"GUARDSIZE64=(%2),"\
"PAGEFRAMESIZE=PAGEABLE1MEG,TYPE=PAGEABLE,SEGMENTS=(%2),"\
"ORIGIN=(%1),TTOKEN=(%4),RETCODE=%0,MF=(E,(%3))"\
::"m"(iarv64_rc),"r"(&origin),"r"(&segments),"r"(&wgetstor),"r"(ttkn));
break;
}

if (0 != iarv64_rc) {
return (void *)0;
}
return (void *)origin;
}

#pragma prolog(omrallocate_2G_pages,"MYPROLOG")
#pragma epilog(omrallocate_2G_pages,"MYEPILOG")

Expand Down Expand Up @@ -211,7 +266,7 @@ void * omrallocate_2G_pages(int *num2GBUnits, int *userExtendedPrivateAreaMemory
__asm(" IARV64 PLISTVER=MAX,MF=(L,MGETSTOR)":"DS"(mgetstor));

/*
* Allocate 4KB pages in 2G-32G range using IARV64 system macro.
* Allocate 4KB pages above 2GB bar using IARV64 system macro.
* Memory allocated is freed using omrfree_memory_above_bar().
*
* @params[in] numMBSegments Number of 1MB segments to be allocated
Expand Down Expand Up @@ -253,6 +308,54 @@ void * omrallocate_4K_pages_in_userExtendedPrivateArea(int *numMBSegments, int *
return (void *)origin;
}

#pragma prolog(omrallocate_4K_pages_guarded_in_userExtendedPrivateArea,"MYPROLOG")
#pragma epilog(omrallocate_4K_pages_guarded_in_userExtendedPrivateArea,"MYEPILOG")

__asm(" IARV64 PLISTVER=MAX,MF=(L,TGETSTOR)":"DS"(tgetstor));

/*
* Allocate 4KB pages guarded above 2G bar using IARV64 system macro.
* Memory allocated is freed using omrfree_memory_above_bar().
*
* @params[in] numMBSegments Number of 1MB segments to be allocated
* @params[in] userExtendedPrivateAreaMemoryType capability of OS: 0 - general, 1 - 2G-32G range, 2 - 2G-64G range
*
* @return pointer to memory allocated, NULL on failure.
*/
void *omrallocate_4K_pages_guarded_in_userExtendedPrivateArea(int *numMBSegments, int *userExtendedPrivateAreaMemoryType, const char *ttkn) {
long segments;
long origin;

@joransiu joransiu Jun 23, 2026

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These variables should be initialized.

long useMemoryType = *userExtendedPrivateAreaMemoryType;
int iarv64_rc = 0;

__asm(" IARV64 PLISTVER=MAX,MF=(L,TGETSTOR)":"DS"(wgetstor));

segments = *numMBSegments;
wgetstor = tgetstor;

switch (useMemoryType) {
case ZOS64_VMEM_ABOVE_BAR_GENERAL:
break;

@joransiu joransiu Jun 23, 2026

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Since iarv64_rc is initialized to 0, won't we return a potentially garbage (uninitialized) value of origin?

case ZOS64_VMEM_2_TO_32G:
__asm(" IARV64 REQUEST=GETSTOR,COND=YES,SADMP=NO,CONTROL=UNAUTH,USE2GTO32G=YES,"\
"GUARDSIZE64=(%2),PAGEFRAMESIZE=4K,SEGMENTS=(%2),"\
"ORIGIN=(%1),TTOKEN=(%4),RETCODE=%0,MF=(E,(%3))"\
::"m"(iarv64_rc),"r"(&origin),"r"(&segments),"r"(&wgetstor),"r"(ttkn));
break;
case ZOS64_VMEM_2_TO_64G:
__asm(" IARV64 REQUEST=GETSTOR,COND=YES,SADMP=NO,CONTROL=UNAUTH,USE2GTO64G=YES,"\
"GUARDSIZE64=(%2),PAGEFRAMESIZE=4K,SEGMENTS=(%2),"\
"ORIGIN=(%1),TTOKEN=(%4),RETCODE=%0,MF=(E,(%3))"\
::"m"(iarv64_rc),"r"(&origin),"r"(&segments),"r"(&wgetstor),"r"(ttkn));
break;
}

if (0 != iarv64_rc) {
return (void *)0;
}
return (void *)origin;
}

#pragma prolog(omrallocate_4K_pages_above_bar,"MYPROLOG")
#pragma epilog(omrallocate_4K_pages_above_bar,"MYEPILOG")

Expand Down Expand Up @@ -287,6 +390,41 @@ void * omrallocate_4K_pages_above_bar(int *numMBSegments, const char * ttkn) {
return (void *)origin;
}

#pragma prolog(omrallocate_4K_pages_guarded_above_bar,"MYPROLOG")
#pragma epilog(omrallocate_4K_pages_guarded_above_bar,"MYEPILOG")

__asm(" IARV64 PLISTVER=MAX,MF=(L,EGETSTOR)":"DS"(egetstor));

/*
* Allocate 4KB pages guarded using IARV64 system macro.
* Memory allocated is freed using omrfree_memory_above_bar().
*
* @params[in] numMBSegments Number of 1MB segments to be allocated
*
* @return pointer to memory allocated, NULL on failure.
*/
void *omrallocate_4K_pages_guarded_above_bar(int *numMBSegments, const char *ttkn) {
long segments;
long origin;
int iarv64_rc = 0;

__asm(" IARV64 PLISTVER=MAX,MF=(L,EGETSTOR)":"DS"(wgetstor));

segments = *numMBSegments;
wgetstor = rgetstor;

@joransiu joransiu Jun 23, 2026

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rgetstor should be egetstor.


__asm(" IARV64 REQUEST=GETSTOR,COND=YES,SADMP=NO,"\
"GUARDSIZE=(%2),"\
"CONTROL=UNAUTH,PAGEFRAMESIZE=4K,"\
"SEGMENTS=(%2),ORIGIN=(%1),TTOKEN=(%4),RETCODE=%0,MF=(E,(%3))"\
::"m"(iarv64_rc),"r"(&origin),"r"(&segments),"r"(&wgetstor),"r"(ttkn));

if (0 != iarv64_rc) {
return (void *)0;
}
return (void *)origin;
}

#pragma prolog(omrfree_memory_above_bar,"MYPROLOG")
#pragma epilog(omrfree_memory_above_bar,"MYEPILOG")

Expand All @@ -313,6 +451,77 @@ int omrfree_memory_above_bar(void *address, const char * ttkn){
return iarv64_rc;
}

#pragma prolog(omrremove_guard,"MYPROLOG")
#pragma epilog(omrremove_guard,"MYEPILOG")

__asm(" IARV64 PLISTVER=MAX,MF=(L,FGETSTOR)":"DS"(fgetstor));

/*
* Remove guard for memory allocated using IARV64 system macro.
*
* @params[in] address pointer to memory region to be freed
* @params[in] numMBSegments Number of 1MB segments to be allocated
*
* @return non-zero if memory is not freed successfully, 0 otherwise.
* 04 - Operation completed successfully but with exceptions.
* One or more segments in the memory object are already
* in the requested state.
* 08 - Request was rejected because there was insufficient
* storage to satisfy the request.
*/
int omrremove_guard(void *address, int *numMBSegments){
void * memObjConvertStart;
int iarv64_rc = 0;
long segments;

__asm(" IARV64 PLISTVER=MAX,MF=(L,FGETSTOR)":"DS"(wgetstor));

memObjConvertStart = address;
wgetstor = fgetstor;
segments = *numMBSegments;

__asm(" IARV64 REQUEST=CHANGEGUARD,CONVERT=FROMGUARD,COND=YES,"\
"CONVERTSTART=(%2),CONVERTSIZE64=(%3),"\
"RETCODE=%0,MF=(E,(%1))"\
::"m"(iarv64_rc),"r"(&wgetstor),"r"(&memObjConvertStart),"r"(&segments));
return iarv64_rc;
}

#pragma prolog(omradd_guard,"MYPROLOG")
#pragma epilog(omradd_guard,"MYEPILOG")

__asm(" IARV64 PLISTVER=MAX,MF=(L,DGETSTOR)":"DS"(dgetstor));

/*
* Add guard to memory allocated using IARV64 system macro.
*
* @params[in] address pointer to memory region to be freed
*
* @return non-zero if memory is not freed successfully, 0 otherwise.
* 04 - Operation completed successfully but with exceptions.
* One or more segments in the memory object are already
* in the requested state.
* 08 - Request was rejected because there was insufficient
* storage to satisfy the request.
*/
int omradd_guard(void *address, int *numMBSegments) {
void * memObjConvertStart;
int iarv64_rc = 0;
long segments;

__asm(" IARV64 PLISTVER=MAX,MF=(L,DGETSTOR)":"DS"(wgetstor));

memObjConvertStart = address;
wgetstor = dgetstor;
segments = *numMBSegments;

__asm(" IARV64 REQUEST=CHANGEGUARD,CONVERT=TOGUARD,COND=YES,"\
"CONVERTSTART=(%2),CONVERTSIZE64=(%3),"\
"RETCODE=%0,MF=(E,(%1))"\
::"m"(iarv64_rc),"r"(&wgetstor),"r"(&memObjConvertStart),"r"(&segments));
return iarv64_rc;
}

#pragma prolog(omrdiscard_data,"MYPROLOG")
#pragma epilog(omrdiscard_data,"MYEPILOG")

Expand Down
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