[ELF] - Teach LLD to recognize PT_OPENBSD_BOOTDATA

[grimar]

Summary

Minor patch to fix PR31288

OpenBSD commit:
https://github.com/openbsd/src/commit/d39116912b9536bd77326260dc5c6e593fd4ee24

[ruiu]

ELF/LinkerScript.cpp

1862

Sort.

test/ELF/linkerscript/openbsd-bootdata.s

2–4

Why did you need .text?

Also, please do not use line continuations (\) in echo. It makes output messages hard to read when this test fails.

11–20

Remove these lines because we are not interested in testing them.

[grimar]

ELF/LinkerScript.cpp

1862

Sorted by value, like others entries.

[ruiu]

ELF/LinkerScript.cpp

1862

But why? Probably nobody memorizes these numbers.

[grimar]

ELF/LinkerScript.cpp

1862

Hmmm. For consistency. Whole StringSwitch is sorted by values.
Also them are sorted in ELF.h in the same way and it is comfortable to compare missings if needed.

[ruiu]

ELF/LinkerScript.cpp

1862

Consistency with ELF.h may make sense, though I'm tempted to sort them here. OK in either way.

[grimar]

• Addressed review comments.

test/ELF/linkerscript/openbsd-bootdata.s

2–4

Right, I think i do not need anything except what is in current diff, we can just check that lld creates header.

[ruiu]

Now that I wonder why we need one file per each program header type. Can you consolidate?

[grimar]

In D27458#614630, @ruiu wrote:

Now that I wonder why we need one file per each program header type. Can you consolidate?

You mean combine testcases for OpenBSD into single file ? Probably yes, I'll try tomorrow.

[ruiu]

LGTM. Let's do cleanup in a followup patch.

[grimar]

In D27458#614665, @ruiu wrote:

LGTM. Let's do cleanup in a followup patch.

Thanks. By the way, after looking closer, openbsd-randomize.s (PT_OPENBSD_RANDOMIZE) and openbsd-wxneeded.s (PT_OPENBSD_WXNEEDED) are a bit different form this.
Both of them involve additional logic in LLD.

PT_OPENBSD_WXNEEDED relative to -z wxneeded,
PT_OPENBSD_RANDOMIZE is generated when we have ".openbsd.randomdata" section.
I would probably not combine their testcases.

May be we should just rename this testcase to openbsd-common-phdrs.s and use for all OpenBSD program headers that do not require any special logic ?

ELF/LinkerScript.cpp

unsigned Ret = StringSwitch<unsigned>(Tok)
                      .Case("PT_SHLIB", PT_SHLIB)
                      .Case("PT_PHDR", PT_PHDR)
                      .Case("PT_TLS", PT_TLS)
                      .Case("PT_GNU_EH_FRAME", PT_GNU_EH_FRAME)
                      .Case("PT_GNU_STACK", PT_GNU_STACK)
                      .Case("PT_GNU_RELRO", PT_GNU_RELRO)
                      .Case("PT_OPENBSD_RANDOMIZE", PT_OPENBSD_RANDOMIZE)
                      .Case("PT_OPENBSD_WXNEEDED", PT_OPENBSD_WXNEEDED)
+                     .Case("PT_OPENBSD_BOOTDATA", PT_OPENBSD_BOOTDATA)
                      .Default(-1);
 
   if (Ret == (unsigned)-1) {
     setError("invalid program header type: " + Tok);
     return PT_NULL;
   }
   return Ret;
 }

test/ELF/linkerscript/openbsd-bootdata.s

+# RUN: llvm-mc -filetype=obj -triple=i686-unknown-linux %s -o %t.o
+# RUN: echo "PHDRS { text PT_LOAD FILEHDR PHDRS; boot PT_OPENBSD_BOOTDATA; } \
+# RUN:       SECTIONS { . = SIZEOF_HEADERS; \
+# RUN:         .text : { *(.text) } \
+# RUN:         .openbsd.bootdata : { *(.openbsd.bootdata) } : boot }" > %t.script
+# RUN: ld.lld --script %t.script %t.o -o %t
+# RUN: llvm-readobj --program-headers -s %t | FileCheck %s
+
+# CHECK:      ProgramHeader {
+# CHECK:        Type: PT_OPENBSD_BOOTDATA (0x65A41BE6)
+# CHECK-NEXT:   Offset: 0x74
+# CHECK-NEXT:   VirtualAddress: 0x74
+# CHECK-NEXT:   PhysicalAddress: 0x74
+# CHECK-NEXT:   FileSize: 8
+# CHECK-NEXT:   MemSize: 8
+# CHECK-NEXT:   Flags [ (0x4)
+# CHECK-NEXT:     PF_R (0x4)
+# CHECK-NEXT:   ]
+# CHECK-NEXT:   Alignment: 1
+# CHECK-NEXT: }
+
+.section .openbsd.bootdata, "a"
+.quad 0