hwpmc: partially depessimize munmap handling if the module is not loaded
HWPMC_HOOKS is enabled in GENERIC and triggers some work avoidable in the common (module not loaded) case. In particular this avoids permission checks + lock downgrade singlethreaded and in cases were an executable mapping is found the pmc sx lock is no longer bounced. Note this is a band aid. MFC after: 1 week
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543b2f425d
commit
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Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=312724
@ -174,6 +174,9 @@ extern const int pmc_kernel_version;
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/* PMC soft per cpu trapframe */
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extern struct trapframe pmc_tf[MAXCPU];
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/* Quick check if preparatory work is necessary */
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#define PMC_HOOK_INSTALLED(cmd) __predict_false(pmc_hook != NULL)
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/* Hook invocation; for use within the kernel */
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#define PMC_CALL_HOOK(t, cmd, arg) \
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do { \
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@ -526,6 +526,7 @@ sys_munmap(td, uap)
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#ifdef HWPMC_HOOKS
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struct pmckern_map_out pkm;
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vm_map_entry_t entry;
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bool pmc_handled;
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#endif
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vm_offset_t addr;
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vm_size_t size, pageoff;
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@ -551,20 +552,24 @@ sys_munmap(td, uap)
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return (EINVAL);
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vm_map_lock(map);
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#ifdef HWPMC_HOOKS
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/*
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* Inform hwpmc if the address range being unmapped contains
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* an executable region.
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*/
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pkm.pm_address = (uintptr_t) NULL;
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if (vm_map_lookup_entry(map, addr, &entry)) {
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for (;
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entry != &map->header && entry->start < addr + size;
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entry = entry->next) {
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if (vm_map_check_protection(map, entry->start,
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entry->end, VM_PROT_EXECUTE) == TRUE) {
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pkm.pm_address = (uintptr_t) addr;
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pkm.pm_size = (size_t) size;
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break;
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pmc_handled = false;
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if (PMC_HOOK_INSTALLED(PMC_FN_MUNMAP)) {
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pmc_handled = true;
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/*
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* Inform hwpmc if the address range being unmapped contains
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* an executable region.
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*/
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pkm.pm_address = (uintptr_t) NULL;
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if (vm_map_lookup_entry(map, addr, &entry)) {
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for (;
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entry != &map->header && entry->start < addr + size;
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entry = entry->next) {
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if (vm_map_check_protection(map, entry->start,
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entry->end, VM_PROT_EXECUTE) == TRUE) {
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pkm.pm_address = (uintptr_t) addr;
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pkm.pm_size = (size_t) size;
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break;
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}
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}
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}
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}
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@ -572,14 +577,16 @@ sys_munmap(td, uap)
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vm_map_delete(map, addr, addr + size);
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#ifdef HWPMC_HOOKS
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/* downgrade the lock to prevent a LOR with the pmc-sx lock */
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vm_map_lock_downgrade(map);
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if (pkm.pm_address != (uintptr_t) NULL)
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PMC_CALL_HOOK(td, PMC_FN_MUNMAP, (void *) &pkm);
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vm_map_unlock_read(map);
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#else
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vm_map_unlock(map);
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if (__predict_false(pmc_handled)) {
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/* downgrade the lock to prevent a LOR with the pmc-sx lock */
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vm_map_lock_downgrade(map);
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if (pkm.pm_address != (uintptr_t) NULL)
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PMC_CALL_HOOK(td, PMC_FN_MUNMAP, (void *) &pkm);
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vm_map_unlock_read(map);
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} else
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#endif
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vm_map_unlock(map);
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/* vm_map_delete returns nothing but KERN_SUCCESS anyway */
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return (0);
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}
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