[ELF] Full support for -n (--nmagic) and -N (--omagic) via common page

The -n (--nmagic) disables page alignment, and acts as a -Bstatic
The -N (--omagic) does what -n does but also marks the executable segment as
writeable. As page alignment is disabled headers are not allocated unless
explicit in the linker script.

To disable page alignment in LLD we choose to set the page sizes to 1 so
that any alignment based on the page size does nothing. To set the
Target->PageSize to 1 we implement -z common-page-size, which has the side
effect of allowing the user to set the value as well.

Setting the page alignments to 1 does mean that any use of
CONSTANT(MAXPAGESIZE) or CONSTANT(COMMONPAGESIZE) in a linker script will
return 1, unlike in ld.bfd. However given that -n and -N disable paging
these probably shouldn't be used in a linker script where -n or -N is in
use.

Differential Revision: https://reviews.llvm.org/D61688

llvm-svn: 360593

1 files changed, 223 insertions, 0 deletions

diff --git a/lld/test/ELF/common-page.s b/lld/test/ELF/common-page.s
new file mode 100644
index 00000000000..4734a49a84e
--- /dev/null
+++ b/lld/test/ELF/common-page.s
@@ -0,0 +1,223 @@
+# REQUIRES: x86
+
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t
+
+# exits with return code 42 on linux
+.globl _start
+_start:
+  nop
+
+# Increase max-page-size to 64k while using the default x86_64 common page size
+# of 4k. If the last loadable segment is executable then lld aligns the next
+# section using the common page size.
+
+# RUN: ld.lld -z max-page-size=0x10000 -z common-page-size=0x1000 %t -o %t2
+# RUN: llvm-readobj --sections -l %t2 | FileCheck --check-prefix=CHECK-MAX %s
+
+# CHECK-MAX:      Sections [
+# CHECK-MAX-NEXT:   Section {
+# CHECK-MAX-NEXT:     Index: 0
+# CHECK-MAX-NEXT:     Name:  (0)
+# CHECK-MAX-NEXT:     Type: SHT_NULL (0x0)
+# CHECK-MAX-NEXT:     Flags [ (0x0)
+# CHECK-MAX-NEXT:     ]
+# CHECK-MAX-NEXT:     Address: 0x0
+# CHECK-MAX-NEXT:     Offset: 0x0
+# CHECK-MAX-NEXT:     Size: 0
+# CHECK-MAX-NEXT:     Link: 0
+# CHECK-MAX-NEXT:     Info: 0
+# CHECK-MAX-NEXT:     AddressAlignment: 0
+# CHECK-MAX-NEXT:     EntrySize: 0
+# CHECK-MAX-NEXT:   }
+# CHECK-MAX-NEXT:   Section {
+# CHECK-MAX-NEXT:     Index: 1
+# CHECK-MAX-NEXT:     Name: .text (1)
+# CHECK-MAX-NEXT:     Type: SHT_PROGBITS (0x1)
+# CHECK-MAX-NEXT:     Flags [ (0x6)
+# CHECK-MAX-NEXT:       SHF_ALLOC (0x2)
+# CHECK-MAX-NEXT:       SHF_EXECINSTR (0x4)
+# CHECK-MAX-NEXT:     ]
+# CHECK-MAX-NEXT:     Address: 0x210000
+# CHECK-MAX-NEXT:     Offset: 0x10000
+# CHECK-MAX-NEXT:     Size: 1
+# CHECK-MAX-NEXT:     Link: 0
+# CHECK-MAX-NEXT:     Info: 0
+# CHECK-MAX-NEXT:     AddressAlignment: 4
+# CHECK-MAX-NEXT:     EntrySize: 0
+# CHECK-MAX-NEXT:   }
+# CHECK-MAX-NEXT:   Section {
+# CHECK-MAX-NEXT:     Index: 2
+# CHECK-MAX-NEXT:     Name: .comment (7)
+# CHECK-MAX-NEXT:     Type: SHT_PROGBITS (0x1)
+# CHECK-MAX-NEXT:     Flags [ (0x30)
+# CHECK-MAX-NEXT:       SHF_MERGE (0x10)
+# CHECK-MAX-NEXT:       SHF_STRINGS (0x20)
+# CHECK-MAX-NEXT:     ]
+# CHECK-MAX-NEXT:     Address: 0x0
+# CHECK-MAX-NEXT:     Offset: 0x11000
+# CHECK-MAX-NEXT:     Size: 8
+# CHECK-MAX-NEXT:     Link: 0
+# CHECK-MAX-NEXT:     Info: 0
+# CHECK-MAX-NEXT:     AddressAlignment: 1
+# CHECK-MAX-NEXT:     EntrySize: 1
+
+# CHECK-MAX: ProgramHeaders [
+# CHECK-MAX-NEXT:   ProgramHeader {
+# CHECK-MAX-NEXT:     Type: PT_PHDR (0x6)
+# CHECK-MAX-NEXT:     Offset: 0x40
+# CHECK-MAX-NEXT:     VirtualAddress: 0x200040
+# CHECK-MAX-NEXT:     PhysicalAddress: 0x200040
+# CHECK-MAX-NEXT:     FileSize: 224
+# CHECK-MAX-NEXT:     MemSize: 224
+# CHECK-MAX-NEXT:     Flags [ (0x4)
+# CHECK-MAX-NEXT:       PF_R (0x4)
+# CHECK-MAX-NEXT:     ]
+# CHECK-MAX-NEXT:     Alignment: 8
+# CHECK-MAX-NEXT:   }
+# CHECK-MAX-NEXT:   ProgramHeader {
+# CHECK-MAX-NEXT:     Type: PT_LOAD (0x1)
+# CHECK-MAX-NEXT:     Offset: 0x0
+# CHECK-MAX-NEXT:     VirtualAddress: 0x200000
+# CHECK-MAX-NEXT:     PhysicalAddress: 0x200000
+# CHECK-MAX-NEXT:     FileSize: 288
+# CHECK-MAX-NEXT:     MemSize: 288
+# CHECK-MAX-NEXT:     Flags [ (0x4)
+# CHECK-MAX-NEXT:       PF_R (0x4)
+# CHECK-MAX-NEXT:     ]
+# CHECK-MAX-NEXT:     Alignment: 65536
+# CHECK-MAX-NEXT:   }
+# CHECK-MAX-NEXT:   ProgramHeader {
+# CHECK-MAX-NEXT:     Type: PT_LOAD (0x1)
+# CHECK-MAX-NEXT:     Offset: 0x10000
+# CHECK-MAX-NEXT:     VirtualAddress: 0x210000
+# CHECK-MAX-NEXT:     PhysicalAddress: 0x210000
+# CHECK-MAX-NEXT:     FileSize: 4096
+# CHECK-MAX-NEXT:     MemSize: 4096
+# CHECK-MAX-NEXT:     Flags [ (0x5)
+# CHECK-MAX-NEXT:       PF_R (0x4)
+# CHECK-MAX-NEXT:       PF_X (0x1)
+# CHECK-MAX-NEXT:     ]
+# CHECK-MAX-NEXT:     Alignment: 65536
+# CHECK-MAX-NEXT:   }
+# CHECK-MAX-NEXT:   ProgramHeader {
+# CHECK-MAX-NEXT:     Type: PT_GNU_STACK (0x6474E551)
+# CHECK-MAX-NEXT:     Offset: 0x0
+# CHECK-MAX-NEXT:     VirtualAddress: 0x0
+# CHECK-MAX-NEXT:     PhysicalAddress: 0x0
+# CHECK-MAX-NEXT:     FileSize: 0
+# CHECK-MAX-NEXT:     MemSize: 0
+# CHECK-MAX-NEXT:     Flags [ (0x6)
+# CHECK-MAX-NEXT:       PF_R (0x4)
+# CHECK-MAX-NEXT:       PF_W (0x2)
+# CHECK-MAX-NEXT:     ]
+# CHECK-MAX-NEXT:     Alignment: 0
+
+# Increase common-page-size to max-page-size. Expect to see a larger offset
+# of the first Section after the executable loadable segment due to the higher
+# alignment requirement.
+
+# RUN: ld.lld -z max-page-size=0x10000 -z common-page-size=0x10000 %t -o %t3
+# RUN: llvm-readobj --sections -l %t3 | FileCheck --check-prefix=CHECK-COMMON %s
+
+# Check that we truncate common-page-size to max-page-size
+
+# RUN: ld.lld -z max-page-size=0x10000 -z common-page-size=0x100000 %t -o %t4
+# RUN: llvm-readobj --sections -l %t4 | FileCheck --check-prefix=CHECK-COMMON %s
+
+# CHECK-COMMON: Sections [
+# CHECK-COMMON-NEXT:   Section {
+# CHECK-COMMON-NEXT:     Index: 0
+# CHECK-COMMON-NEXT:     Name:  (0)
+# CHECK-COMMON-NEXT:     Type: SHT_NULL (0x0)
+# CHECK-COMMON-NEXT:     Flags [ (0x0)
+# CHECK-COMMON-NEXT:     ]
+# CHECK-COMMON-NEXT:     Address: 0x0
+# CHECK-COMMON-NEXT:     Offset: 0x0
+# CHECK-COMMON-NEXT:     Size: 0
+# CHECK-COMMON-NEXT:     Link: 0
+# CHECK-COMMON-NEXT:     Info: 0
+# CHECK-COMMON-NEXT:     AddressAlignment: 0
+# CHECK-COMMON-NEXT:     EntrySize: 0
+# CHECK-COMMON-NEXT:   }
+# CHECK-COMMON-NEXT:   Section {
+# CHECK-COMMON-NEXT:     Index: 1
+# CHECK-COMMON-NEXT:     Name: .text (1)
+# CHECK-COMMON-NEXT:     Type: SHT_PROGBITS (0x1)
+# CHECK-COMMON-NEXT:     Flags [ (0x6)
+# CHECK-COMMON-NEXT:       SHF_ALLOC (0x2)
+# CHECK-COMMON-NEXT:       SHF_EXECINSTR (0x4)
+# CHECK-COMMON-NEXT:     ]
+# CHECK-COMMON-NEXT:     Address: 0x210000
+# CHECK-COMMON-NEXT:     Offset: 0x10000
+# CHECK-COMMON-NEXT:     Size: 1
+# CHECK-COMMON-NEXT:     Link: 0
+# CHECK-COMMON-NEXT:     Info: 0
+# CHECK-COMMON-NEXT:     AddressAlignment: 4
+# CHECK-COMMON-NEXT:     EntrySize: 0
+# CHECK-COMMON-NEXT:   }
+# CHECK-COMMON-NEXT:   Section {
+# CHECK-COMMON-NEXT:     Index: 2
+# CHECK-COMMON-NEXT:     Name: .comment (7)
+# CHECK-COMMON-NEXT:     Type: SHT_PROGBITS (0x1)
+# CHECK-COMMON-NEXT:     Flags [ (0x30)
+# CHECK-COMMON-NEXT:       SHF_MERGE (0x10)
+# CHECK-COMMON-NEXT:       SHF_STRINGS (0x20)
+# CHECK-COMMON-NEXT:     ]
+# CHECK-COMMON-NEXT:     Address: 0x0
+# CHECK-COMMON-NEXT:     Offset: 0x20000
+# CHECK-COMMON-NEXT:     Size: 8
+# CHECK-COMMON-NEXT:     Link: 0
+# CHECK-COMMON-NEXT:     Info: 0
+# CHECK-COMMON-NEXT:     AddressAlignment: 1
+# CHECK-COMMON-NEXT:     EntrySize: 1
+
+# CHECK-COMMON: ProgramHeaders [
+# CHECK-COMMON-NEXT:   ProgramHeader {
+# CHECK-COMMON-NEXT:     Type: PT_PHDR (0x6)
+# CHECK-COMMON-NEXT:     Offset: 0x40
+# CHECK-COMMON-NEXT:     VirtualAddress: 0x200040
+# CHECK-COMMON-NEXT:     PhysicalAddress: 0x200040
+# CHECK-COMMON-NEXT:     FileSize: 224
+# CHECK-COMMON-NEXT:     MemSize: 224
+# CHECK-COMMON-NEXT:     Flags [ (0x4)
+# CHECK-COMMON-NEXT:       PF_R (0x4)
+# CHECK-COMMON-NEXT:     ]
+# CHECK-COMMON-NEXT:     Alignment: 8
+# CHECK-COMMON-NEXT:   }
+# CHECK-COMMON-NEXT:   ProgramHeader {
+# CHECK-COMMON-NEXT:     Type: PT_LOAD (0x1)
+# CHECK-COMMON-NEXT:     Offset: 0x0
+# CHECK-COMMON-NEXT:     VirtualAddress: 0x200000
+# CHECK-COMMON-NEXT:     PhysicalAddress: 0x200000
+# CHECK-COMMON-NEXT:     FileSize: 288
+# CHECK-COMMON-NEXT:     MemSize: 288
+# CHECK-COMMON-NEXT:     Flags [ (0x4)
+# CHECK-COMMON-NEXT:       PF_R (0x4)
+# CHECK-COMMON-NEXT:     ]
+# CHECK-COMMON-NEXT:     Alignment: 65536
+# CHECK-COMMON-NEXT:   }
+# CHECK-COMMON-NEXT:   ProgramHeader {
+# CHECK-COMMON-NEXT:     Type: PT_LOAD (0x1)
+# CHECK-COMMON-NEXT:     Offset: 0x10000
+# CHECK-COMMON-NEXT:     VirtualAddress: 0x210000
+# CHECK-COMMON-NEXT:     PhysicalAddress: 0x210000
+# CHECK-COMMON-NEXT:     FileSize: 65536
+# CHECK-COMMON-NEXT:     MemSize: 65536
+# CHECK-COMMON-NEXT:     Flags [ (0x5)
+# CHECK-COMMON-NEXT:       PF_R (0x4)
+# CHECK-COMMON-NEXT:       PF_X (0x1)
+# CHECK-COMMON-NEXT:     ]
+# CHECK-COMMON-NEXT:     Alignment: 65536
+# CHECK-COMMON-NEXT:   }
+# CHECK-COMMON-NEXT:   ProgramHeader {
+# CHECK-COMMON-NEXT:     Type: PT_GNU_STACK (0x6474E551)
+# CHECK-COMMON-NEXT:     Offset: 0x0
+# CHECK-COMMON-NEXT:     VirtualAddress: 0x0
+# CHECK-COMMON-NEXT:     PhysicalAddress: 0x0
+# CHECK-COMMON-NEXT:     FileSize: 0
+# CHECK-COMMON-NEXT:     MemSize: 0
+# CHECK-COMMON-NEXT:     Flags [ (0x6)
+# CHECK-COMMON-NEXT:       PF_R (0x4)
+# CHECK-COMMON-NEXT:       PF_W (0x2)
+# CHECK-COMMON-NEXT:     ]
+# CHECK-COMMON-NEXT:     Alignment: 0