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[PATCH] S/390 Some comment fixes
- From: "Andreas Krebbel" <krebbel at linux dot vnet dot ibm dot com>
- To: binutils at sourceware dot org
- Date: Tue, 27 Mar 2012 17:14:29 +0200
- Subject: [PATCH] S/390 Some comment fixes
Hi,
the attached patch fixes a bunch of comments which say that the PLT
slot parameter points to the symbol table. In fact it points to the
relocation in the .rela.plt section. I stumbled over that several
times now so its about time to fix it.
Will commit together with the other cleanup patches.
Bye,
-Andreas-
2012-03-27 Andreas Krebbel <Andreas.Krebbel@de.ibm.com>
* elf64-s390.c: Fix several comments regarding PLT entry
description.
* elf32-s390.c: Likewise.
---
bfd/elf32-s390.c | 20 ++++++++++----------
bfd/elf64-s390.c | 20 ++++++++++----------
2 files changed, 20 insertions(+), 20 deletions(-)
Index: bfd/elf64-s390.c
===================================================================
--- bfd/elf64-s390.c.orig
+++ bfd/elf64-s390.c
@@ -540,18 +540,18 @@ elf_s390_is_local_label_name (abfd, name
RET1: BASR 1,0 # 2 bytes Return from GOT 1st time
LGF 1,12(1) # 6 bytes Load offset in symbl table in r1
BRCL 15,-x # 6 bytes Jump to start of PLT
- .long ? # 4 bytes offset into symbol table
+ .long ? # 4 bytes offset into .rela.plt
Total = 32 bytes per PLT entry
Fixup at offset 2: relative address to GOT entry
Fixup at offset 22: relative branch to PLT0
- Fixup at offset 28: 32 bit offset into symbol table
+ Fixup at offset 28: 32 bit offset into .rela.plt
- A 32 bit offset into the symbol table is enough. It allows for symbol
- tables up to a size of 2 gigabyte. A single dynamic object (the main
- program, any shared library) is limited to 4GB in size and I want to see
- the program that manages to have a symbol table of more than 2 GB with a
- total size of at max 4 GB. */
+ A 32 bit offset into the symbol table is enough. It allows for
+ .rela.plt sections up to a size of 2 gigabyte. A single dynamic
+ object (the main program, any shared library) is limited to 4GB in
+ size. Having a .rela.plt of 2GB would already make the .plt
+ section bigger than 8GB. */
static const bfd_byte elf_s390x_plt_entry[PLT_ENTRY_SIZE] =
{
@@ -565,8 +565,8 @@ static const bfd_byte elf_s390x_plt_entr
};
/* The first PLT entry pushes the offset into the symbol table
- from R1 onto the stack at 8(15) and the loader object info
- at 12(15), loads the loader address in R1 and jumps to it. */
+ from R1 onto the stack at 56(15) and the loader object info
+ at 48(15), loads the loader address in R1 and jumps to it. */
/* The first entry in the PLT:
@@ -3065,7 +3065,7 @@ elf_s390_finish_dynamic_symbol (bfd *out
bfd_put_32 (output_bfd, - (PLT_FIRST_ENTRY_SIZE +
(PLT_ENTRY_SIZE * plt_index) + 22)/2,
htab->elf.splt->contents + h->plt.offset + 24);
- /* Fixup offset into symbol table */
+ /* Fixup offset into .rela.plt section. */
bfd_put_32 (output_bfd, plt_index * sizeof (Elf64_External_Rela),
htab->elf.splt->contents + h->plt.offset + 28);
Index: bfd/elf32-s390.c
===================================================================
--- bfd/elf32-s390.c.orig
+++ bfd/elf32-s390.c
@@ -509,7 +509,7 @@ elf_s390_is_local_label_name (abfd, name
The GOT holds the address in the PLT to be executed.
The loader then gets:
24(15) = Pointer to the structure describing the object.
- 28(15) = Offset in symbol table
+ 28(15) = Offset into rela.plt
The loader must then find the module where the function is
and insert the address in the GOT.
@@ -527,7 +527,7 @@ RET1: BASR 1,0 # 2 bytes Return
BRC 15,-x # 4 bytes Jump to start of PLT
.word 0 # 2 bytes filler
.long ? # 4 bytes offset in GOT
- .long ? # 4 bytes offset into symbol table
+ .long ? # 4 bytes offset into rela.plt
This was the general case. There are two additional, optimizes PLT
definitions. One for GOT offsets < 4096 and one for GOT offsets < 32768.
@@ -537,10 +537,10 @@ PLT1: L 1,<offset>(12) # 4 bytes Loa
BCR 15,1 # 2 bytes Jump to address
.word 0,0,0 # 6 bytes filler
RET1: BASR 1,0 # 2 bytes Return from GOT 1st time
- L 1,14(1) # 4 bytes Load offset in symbol table in r1
+ L 1,14(1) # 4 bytes Load offset in rela.plt in r1
BRC 15,-x # 4 bytes Jump to start of PLT
.word 0,0,0 # 6 bytes filler
- .long ? # 4 bytes offset into symbol table
+ .long ? # 4 bytes offset into rela.plt
Second the one for GOT offsets < 32768:
@@ -549,10 +549,10 @@ PLT1: LHI 1,<offset> # 4 bytes Loa
BCR 15,1 # 2 bytes Jump to address
.word 0 # 2 bytes filler
RET1: BASR 1,0 # 2 bytes Return from GOT 1st time
- L 1,14(1) # 4 bytes Load offset in symbol table in r1
+ L 1,14(1) # 4 bytes Load offset in rela.plt in r1
BRC 15,-x # 4 bytes Jump to start of PLT
.word 0,0,0 # 6 bytes filler
- .long ? # 4 bytes offset into symbol table
+ .long ? # 4 bytes offset into rela.plt
Total = 32 bytes per PLT entry
@@ -567,7 +567,7 @@ RET1: BASR 1,0 # 2 bytes Return
BRC 15,-x # 4 bytes Jump to start of PLT
.word 0 # 2 bytes filler
.long ? # 4 bytes address of GOT entry
- .long ? # 4 bytes offset into symbol table */
+ .long ? # 4 bytes offset into rela.plt */
static const bfd_byte elf_s390_plt_entry[PLT_ENTRY_SIZE] =
{
@@ -629,14 +629,14 @@ static const bfd_byte elf_s390_plt_pic16
0x00, 0x00
};
-/* The first PLT entry pushes the offset into the symbol table
+/* The first PLT entry pushes the offset into the rela.plt
from R1 onto the stack at 8(15) and the loader object info
at 12(15), loads the loader address in R1 and jumps to it. */
/* The first entry in the PLT for PIC code:
PLT0:
- ST 1,28(15) # R1 has offset into symbol table
+ ST 1,28(15) # R1 has offset into rela.plt
L 1,4(12) # Get loader ino(object struct address)
ST 1,24(15) # Store address
L 1,8(12) # Entry address of loader in R1
@@ -645,7 +645,7 @@ PLT0:
The first entry in the PLT for static code:
PLT0:
- ST 1,28(15) # R1 has offset into symbol table
+ ST 1,28(15) # R1 has offset into rela.plt
BASR 1,0
L 1,18(0,1) # Get address of GOT
MVC 24(4,15),4(1) # Move loader ino to stack