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powerpc/64: Tool to check head sections location sanity

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Use a tool to check that the location of "fixed sections" are where
we expected them to be, which catches cases the linker script can't
(stubs being added to start of .text section), and which ends up
being neater.

Sample output:

  ERROR: start_text address is c000000000008100, should be c000000000008000
  ERROR: see comments in arch/powerpc/tools/head_check.sh

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Fold in fix from Nick for 4.6 era toolchains]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Nicholas Piggin
2017-05-12 03:40:39 +10:00
committed by Michael Ellerman
parent 951eedebcd
commit c494adefef
4 changed files with 87 additions and 25 deletions
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22
arch/powerpc/kernel/vmlinux.lds.S
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@@ -58,7 +58,6 @@ SECTIONS
#ifdef CONFIG_PPC64
KEEP(*(.head.text.first_256B));
#ifdef CONFIG_PPC_BOOK3E
# define END_FIXED 0x100
#else
KEEP(*(.head.text.real_vectors));
*(.head.text.real_trampolines);
@@ -66,12 +65,8 @@ SECTIONS
*(.head.text.virt_trampolines);
# if defined(CONFIG_PPC_PSERIES) || defined(CONFIG_PPC_POWERNV)
KEEP(*(.head.data.fwnmi_page));
# define END_FIXED 0x8000
# else
# define END_FIXED 0x7000
# endif
#endif
ASSERT((. == END_FIXED), "vmlinux.lds.S: fixed section overflow error");
#else /* !CONFIG_PPC64 */
HEAD_TEXT
#endif
@@ -79,23 +74,6 @@ SECTIONS
__head_end = .;
/*
* If the build dies here, it's likely code in head_64.S is referencing
* labels it can't reach, and the linker inserting stubs without the
* assembler's knowledge. To debug, remove the above assert and
* rebuild. Look for branch stubs in the fixed section region.
*
* Linker stub generation could be allowed in "trampoline"
* sections if absolutely necessary, but this would require
* some rework of the fixed sections. Before resorting to this,
* consider references that have sufficient addressing range,
* (e.g., hand coded trampolines) so the linker does not have
* to add stubs.
*
* Linker stubs at the top of the main text section are currently not
* detected, and will result in a crash at boot due to offsets being
* wrong.
*/
#ifdef CONFIG_PPC64
/*
* BLOCK(0) overrides the default output section alignment because