Merge hell test

@@ -25,10 +25,11 @@
 
 /*      Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
 /*         All Rights Reserved  */
 /*
  * Copyright 2019 Joyent, Inc.
+ * Copyright 2021 Oxide Computer Company
  */
 
 #include <sys/types.h>
 #include <sys/param.h>
 #include <sys/thread.h>

@@ -92,16 +93,18 @@
     size_t, size_t *, size_t *);
 
 #ifdef _ELF32_COMPAT
 /* Link against the non-compat instances when compiling the 32-bit version. */
 extern size_t elf_datasz_max;
+extern size_t elf_zeropg_sz;
 extern void elf_ctx_resize_scratch(elf_core_ctx_t *, size_t);
 extern uint_t elf_nphdr_max;
 extern uint_t elf_nshdr_max;
 extern size_t elf_shstrtab_max;
 #else
 size_t elf_datasz_max = 1 * 1024 * 1024;
+size_t elf_zeropg_sz = 4 * 1024;
 uint_t elf_nphdr_max = 1000;
 uint_t elf_nshdr_max = 10000;
 size_t elf_shstrtab_max = 100 * 1024;
 #endif
 

@@ -2262,11 +2265,11 @@
         u_offset_t poffset, soffset, doffset;
         int error;
         uint_t i, nphdrs, nshdrs;
         struct seg *seg;
         struct as *as = p->p_as;
-        void *bigwad;
+        void *bigwad, *zeropg = NULL;
         size_t bigsize, phdrsz, shdrsz;
         Ehdr *ehdr;
         Phdr *phdr;
         Shdr shdr0;
         caddr_t brkbase, stkbase;

@@ -2574,23 +2577,53 @@
 
                 if (phdr[i].p_filesz == 0)
                         continue;
 
                 /*
+                 * If we hit a region that was mapped PROT_NONE then we cannot
+                 * continue dumping this normally as the kernel would be unable
+                 * to read from the page and that would result in us failing to
+                 * dump the page. As such, any region mapped PROT_NONE, we dump
+                 * as a zero-filled page such that this is still represented in
+                 * the map.
+                 *
                  * If dumping out this segment fails, rather than failing
                  * the core dump entirely, we reset the size of the mapping
                  * to zero to indicate that the data is absent from the core
                  * file and or in the PF_SUNW_FAILURE flag to differentiate
                  * this from mappings that were excluded due to the core file
                  * content settings.
                  */
-                if ((error = core_seg(p, vp, phdr[i].p_offset,
-                    (caddr_t)(uintptr_t)phdr[i].p_vaddr, phdr[i].p_filesz,
-                    rlimit, credp)) == 0) {
-                        continue;
+                if ((phdr[i].p_flags & (PF_R | PF_W | PF_X)) == 0) {
+                        size_t towrite = phdr[i].p_filesz;
+                        size_t curoff = 0;
+
+                        if (zeropg == NULL) {
+                                zeropg = kmem_zalloc(elf_zeropg_sz, KM_SLEEP);
                 }
 
+                        error = 0;
+                        while (towrite != 0) {
+                                size_t len = MIN(towrite, elf_zeropg_sz);
+
+                                error = core_write(vp, UIO_SYSSPACE,
+                                    phdr[i].p_offset + curoff, zeropg, len,
+                                    rlimit, credp);
+                                if (error != 0)
+                                        break;
+
+                                towrite -= len;
+                                curoff += len;
+                        }
+                } else {
+                        error = core_seg(p, vp, phdr[i].p_offset,
+                            (caddr_t)(uintptr_t)phdr[i].p_vaddr,
+                            phdr[i].p_filesz, rlimit, credp);
+                }
+                if (error == 0)
+                        continue;
+
                 if ((sig = lwp->lwp_cursig) == 0) {
                         /*
                          * We failed due to something other than a signal.
                          * Since the space reserved for the segment is now
                          * unused, we stash the errno in the first four