[PATCH] D103815: [LLD][ELF] Fix PT_LOAD program header creation for NO_LOAD sections

[Konstantin Schwarz via Phabricator via llvm-commits]

kschwarz updated this revision to Diff 350563.
kschwarz added a comment.

Test formatting


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D103815/new/

https://reviews.llvm.org/D103815

Files:
  lld/ELF/Writer.cpp
  lld/test/ELF/linkerscript/phdrs-noload.test


Index: lld/test/ELF/linkerscript/phdrs-noload.test
===================================================================
--- /dev/null
+++ lld/test/ELF/linkerscript/phdrs-noload.test
@@ -0,0 +1,51 @@
+# REQUIRES: x86
+# RUN: split-file %s %t
+# RUN: llvm-mc -filetype=obj -triple=x86_64 %t/main.s -o %t.o
+
+## NOLOAD sections do not require a PT_LOAD segment, but they can still occupy
+## memory in the executable image.
+## If two output sections with the same VMA and LMA regions are interleaved by
+## a NOLOAD output section, two separate PT_LOAD segments are required.
+# RUN: ld.lld -T %t/link.ld  %t.o -o %ta
+# RUN: llvm-readelf -S -l %ta | FileCheck %s
+
+# CHECK:       [Nr] Name      Type     Address          Off    Size   ES Flg Lk
+# CHECK-NEXT:  [ 0]           NULL     0000000000000000 000000 000000 00      0
+# CHECK-NEXT:  [ 1] .text     PROGBITS 0000000008000000 001000 000001 00  AX  0
+# CHECK-NEXT:  [ 2] .data     PROGBITS 0000000020000400 001400 000004 00  WA  0
+# CHECK-NEXT:  [ 3] .data2    NOBITS   0000000020000404 001404 000004 00  WA  0
+# CHECK-NEXT:  [ 4] .data3    PROGBITS 0000000020000408 001408 000004 00  WA  0
+# CHECK-NEXT:  [ 5] .data4    PROGBITS 0000000008000009 002009 00000c 00  WA  0
+
+
+# CHECK:       Type       Offset   VirtAddr           PhysAddr           FileSiz  MemSiz   Flg Align
+# CHECK-NEXT:  LOAD       0x001000 0x0000000008000000 0x0000000008000000 0x000001 0x000001 R E 0x1000
+# CHECK-NEXT:  LOAD       0x001400 0x0000000020000400 0x0000000008000001 0x000004 0x000004 RW  0x1000
+# CHECK-NEXT:  LOAD       0x001408 0x0000000020000408 0x0000000008000005 0x000004 0x000004 RW  0x1000
+# CHECK-NEXT:  LOAD       0x002009 0x0000000008000009 0x0000000008000009 0x00000c 0x00000c RW  0x1000
+# CHECK-NEXT:  GNU_STACK  0x000000 0x0000000000000000 0x0000000000000000 0x000000 0x000000 RW  0x0
+
+
+#--- link.ld
+MEMORY {
+    CODE (rx) : ORIGIN = 0x08000000, LENGTH = 512K
+    DATA (rw) : ORIGIN = 0x20000400, LENGTH = 512K
+}
+
+SECTIONS {
+    .text : { *(.text) } > CODE
+    .data : { *(.a.data)} > DATA AT> CODE
+    .data2 (NOLOAD) : { . += 4; } > DATA
+    .data3 : { *(.b.data) } > DATA AT> CODE
+    .data4 : { LONG(-1); LONG(-1); LONG(-1); } > CODE
+}
+
+#--- main.s
+.globl _start
+_start: nop
+
+.section .a.data, "aw"
+.long 0xabcdef01
+
+.section .b.data, "aw"
+.long 0xbcdefa12
Index: lld/ELF/Writer.cpp
===================================================================
--- lld/ELF/Writer.cpp
+++ lld/ELF/Writer.cpp
@@ -2385,9 +2385,13 @@
     }
   }
 
+  bool nonContiguousVMA = false;
   for (OutputSection *sec : outputSections) {
-    if (!needsPtLoad(sec))
+    if (!needsPtLoad(sec)) {
+      if (sec->memRegion && sec->memRegion == load->firstSec->memRegion)
+        nonContiguousVMA = true;
       continue;
+    }
 
     // Normally, sections in partitions other than the current partition are
     // ignored. But partition number 255 is a special case: it contains the
@@ -2411,11 +2415,13 @@
     uint64_t newFlags = computeFlags(sec->getPhdrFlags());
     bool sameLMARegion =
         load && !sec->lmaExpr && sec->lmaRegion == load->firstSec->lmaRegion;
-    if (!(load && newFlags == flags && sec != relroEnd &&
+    if (nonContiguousVMA ||
+        !(load && newFlags == flags && sec != relroEnd &&
           sec->memRegion == load->firstSec->memRegion &&
           (sameLMARegion || load->lastSec == Out::programHeaders))) {
       load = addHdr(PT_LOAD, newFlags);
       flags = newFlags;
+      nonContiguousVMA = false;
     }
 
     load->add(sec);


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