Re: [PATCH 1/2] powerpc/vdso: Remove unused ENTRY in linker scripts

2022-05-09 Thread Alexey Kardashevskiy 




On 5/10/22 06:46, Nathan Chancellor wrote:

When linking vdso{32,64}.so.dbg with ld.lld, there is a warning about
not finding _start for the starting address:

   ld.lld: warning: cannot find entry symbol _start; not setting start address
   ld.lld: warning: cannot find entry symbol _start; not setting start address

Looking at GCC + GNU ld, the entry point address is 0x0:

   $ llvm-readelf -h vdso{32,64}.so.dbg &| rg "(File|Entry point address):"
   File: vdso32.so.dbg
 Entry point address:   0x0
   File: vdso64.so.dbg
 Entry point address:   0x0

This matches what ld.lld emits:

   $ powerpc64le-linux-gnu-readelf -p .comment vdso{32,64}.so.dbg

   File: vdso32.so.dbg

   String dump of section '.comment':
 [ 0]  Linker: LLD 14.0.0
 [14]  clang version 14.0.0 (Fedora 14.0.0-1.fc37)

   File: vdso64.so.dbg

   String dump of section '.comment':
 [ 0]  Linker: LLD 14.0.0
 [14]  clang version 14.0.0 (Fedora 14.0.0-1.fc37)

   $ llvm-readelf -h vdso{32,64}.so.dbg &| rg "(File|Entry point address):"
   File: vdso32.so.dbg
 Entry point address:   0x0
   File: vdso64.so.dbg
 Entry point address:   0x0

Remove ENTRY to remove the warning, as it is unnecessary for the vDSO to
function correctly.



Sounds more like a bugfix to me - _start is simply not defined, I wonder 
why ld is not complaining.



Tested-by: Alexey Kardashevskiy 
Reviewed-by: Alexey Kardashevskiy 




Signed-off-by: Nathan Chancellor 
---
  arch/powerpc/kernel/vdso/vdso32.lds.S | 1 -
  arch/powerpc/kernel/vdso/vdso64.lds.S | 1 -
  2 files changed, 2 deletions(-)

diff --git a/arch/powerpc/kernel/vdso/vdso32.lds.S 
b/arch/powerpc/kernel/vdso/vdso32.lds.S
index 58e0099f70f4..e0d19d74455f 100644
--- a/arch/powerpc/kernel/vdso/vdso32.lds.S
+++ b/arch/powerpc/kernel/vdso/vdso32.lds.S
@@ -13,7 +13,6 @@ OUTPUT_FORMAT("elf32-powerpcle", "elf32-powerpcle", 
"elf32-powerpcle")
  OUTPUT_FORMAT("elf32-powerpc", "elf32-powerpc", "elf32-powerpc")
  #endif
  OUTPUT_ARCH(powerpc:common)
-ENTRY(_start)
  
  SECTIONS

  {
diff --git a/arch/powerpc/kernel/vdso/vdso64.lds.S 
b/arch/powerpc/kernel/vdso/vdso64.lds.S
index 0288cad428b0..1a4a7bc4c815 100644
--- a/arch/powerpc/kernel/vdso/vdso64.lds.S
+++ b/arch/powerpc/kernel/vdso/vdso64.lds.S
@@ -13,7 +13,6 @@ OUTPUT_FORMAT("elf64-powerpcle", "elf64-powerpcle", 
"elf64-powerpcle")
  OUTPUT_FORMAT("elf64-powerpc", "elf64-powerpc", "elf64-powerpc")
  #endif
  OUTPUT_ARCH(powerpc:common64)
-ENTRY(_start)
  
  SECTIONS

  {

[PATCH 1/2] powerpc/vdso: Remove unused ENTRY in linker scripts

2022-05-09 Thread Nathan Chancellor 
When linking vdso{32,64}.so.dbg with ld.lld, there is a warning about
not finding _start for the starting address:

  ld.lld: warning: cannot find entry symbol _start; not setting start address
  ld.lld: warning: cannot find entry symbol _start; not setting start address

Looking at GCC + GNU ld, the entry point address is 0x0:

  $ llvm-readelf -h vdso{32,64}.so.dbg &| rg "(File|Entry point address):"
  File: vdso32.so.dbg
Entry point address:   0x0
  File: vdso64.so.dbg
Entry point address:   0x0

This matches what ld.lld emits:

  $ powerpc64le-linux-gnu-readelf -p .comment vdso{32,64}.so.dbg

  File: vdso32.so.dbg

  String dump of section '.comment':
[ 0]  Linker: LLD 14.0.0
[14]  clang version 14.0.0 (Fedora 14.0.0-1.fc37)

  File: vdso64.so.dbg

  String dump of section '.comment':
[ 0]  Linker: LLD 14.0.0
[14]  clang version 14.0.0 (Fedora 14.0.0-1.fc37)

  $ llvm-readelf -h vdso{32,64}.so.dbg &| rg "(File|Entry point address):"
  File: vdso32.so.dbg
Entry point address:   0x0
  File: vdso64.so.dbg
Entry point address:   0x0

Remove ENTRY to remove the warning, as it is unnecessary for the vDSO to
function correctly.

Signed-off-by: Nathan Chancellor 
---
 arch/powerpc/kernel/vdso/vdso32.lds.S | 1 -
 arch/powerpc/kernel/vdso/vdso64.lds.S | 1 -
 2 files changed, 2 deletions(-)

diff --git a/arch/powerpc/kernel/vdso/vdso32.lds.S 
b/arch/powerpc/kernel/vdso/vdso32.lds.S
index 58e0099f70f4..e0d19d74455f 100644
--- a/arch/powerpc/kernel/vdso/vdso32.lds.S
+++ b/arch/powerpc/kernel/vdso/vdso32.lds.S
@@ -13,7 +13,6 @@ OUTPUT_FORMAT("elf32-powerpcle", "elf32-powerpcle", 
"elf32-powerpcle")
 OUTPUT_FORMAT("elf32-powerpc", "elf32-powerpc", "elf32-powerpc")
 #endif
 OUTPUT_ARCH(powerpc:common)
-ENTRY(_start)
 
 SECTIONS
 {
diff --git a/arch/powerpc/kernel/vdso/vdso64.lds.S 
b/arch/powerpc/kernel/vdso/vdso64.lds.S
index 0288cad428b0..1a4a7bc4c815 100644
--- a/arch/powerpc/kernel/vdso/vdso64.lds.S
+++ b/arch/powerpc/kernel/vdso/vdso64.lds.S
@@ -13,7 +13,6 @@ OUTPUT_FORMAT("elf64-powerpcle", "elf64-powerpcle", 
"elf64-powerpcle")
 OUTPUT_FORMAT("elf64-powerpc", "elf64-powerpc", "elf64-powerpc")
 #endif
 OUTPUT_ARCH(powerpc:common64)
-ENTRY(_start)
 
 SECTIONS
 {
-- 
2.36.1