266 lines
11 KiB
Diff
266 lines
11 KiB
Diff
From 8926dc1cbe8fa3b9ae35bf03ec503bbc40f9cf37 Mon Sep 17 00:00:00 2001
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From: Giuliano Belinassi <gbelinassi@suse.de>
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Date: Thu, 25 Jul 2024 11:54:22 -0300
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Subject: [PATCH] Backport rs6000: Adjust -fpatchable-function-entry* support
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for dual entry
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Original message:
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As the discussion in PR112980, although the current
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implementation for -fpatchable-function-entry* conforms
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with the documentation (making N NOPs be consecutive),
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it's inefficient for both kernel and userspace livepatching
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(see comments in PR for the details).
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So this patch is to change the current implementation by
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emitting the "before" NOPs before global entry point and
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the "after" NOPs after local entry point. The new behavior
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would not keep NOPs to be consecutive, so the documentation
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is updated to emphasize this
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Backport to gcc-13
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Authored-by: Kewen Lin <linkw@linux.ibm.com>
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Backported-by: Giuliano Belinassi <gbelinassi@suse.de>
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PR target/112980
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gcc/ChangeLog:
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* config/rs6000/rs6000-logue.cc (rs6000_output_function_prologue):
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Adjust the handling on patch area emitting with dual entry, remove
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the restriction on "before" NOPs count, not emit "before" NOPs any
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more but only emit "after" NOPs.
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* config/rs6000/rs6000.cc (rs6000_print_patchable_function_entry):
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Adjust by respecting cfun->machine->stop_patch_area_print.
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(rs6000_elf_declare_function_name): For ELFv2 with dual entry, set
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cfun->machine->stop_patch_area_print as true.
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* config/rs6000/rs6000.h (struct machine_function): Remove member
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global_entry_emitted, add new member stop_patch_area_print.
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* doc/invoke.texi (option -fpatchable-function-entry): Adjust the
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documentation for PowerPC ELFv2 dual entry.
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gcc/testsuite/ChangeLog:
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* c-c++-common/patchable_function_entry-default.c: Adjust.
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* gcc.target/powerpc/pr99888-4.c: Likewise.
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* gcc.target/powerpc/pr99888-5.c: Likewise.
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* gcc.target/powerpc/pr99888-6.c: Likewise.
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Signed-off-by: Giuliano Belinassi <gbelinassi@suse.de>
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---
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gcc/config/rs6000/rs6000-logue.cc | 40 +++++--------------
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gcc/config/rs6000/rs6000.cc | 15 +++++--
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gcc/config/rs6000/rs6000.h | 10 +++--
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gcc/doc/invoke.texi | 8 ++--
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.../patchable_function_entry-default.c | 3 --
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gcc/testsuite/gcc.target/powerpc/pr99888-4.c | 4 +-
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gcc/testsuite/gcc.target/powerpc/pr99888-5.c | 4 +-
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gcc/testsuite/gcc.target/powerpc/pr99888-6.c | 4 +-
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8 files changed, 33 insertions(+), 55 deletions(-)
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diff --git a/gcc/config/rs6000/rs6000-logue.cc b/gcc/config/rs6000/rs6000-logue.cc
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index 208404e6864..3835bc943ad 100644
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--- a/gcc/config/rs6000/rs6000-logue.cc
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+++ b/gcc/config/rs6000/rs6000-logue.cc
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@@ -4001,43 +4001,21 @@ rs6000_output_function_prologue (FILE *file)
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fprintf (file, "\tadd 2,2,12\n");
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}
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- unsigned short patch_area_size = crtl->patch_area_size;
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- unsigned short patch_area_entry = crtl->patch_area_entry;
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- /* Need to emit the patching area. */
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- if (patch_area_size > 0)
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- {
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- cfun->machine->global_entry_emitted = true;
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- /* As ELFv2 ABI shows, the allowable bytes between the global
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- and local entry points are 0, 4, 8, 16, 32 and 64 when
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- there is a local entry point. Considering there are two
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- non-prefixed instructions for global entry point prologue
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- (8 bytes), the count for patchable nops before local entry
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- point would be 2, 6 and 14. It's possible to support those
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- other counts of nops by not making a local entry point, but
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- we don't have clear use cases for them, so leave them
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- unsupported for now. */
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- if (patch_area_entry > 0)
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- {
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- if (patch_area_entry != 2
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- && patch_area_entry != 6
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- && patch_area_entry != 14)
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- error ("unsupported number of nops before function entry (%u)",
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- patch_area_entry);
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- rs6000_print_patchable_function_entry (file, patch_area_entry,
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- true);
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- patch_area_size -= patch_area_entry;
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- }
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- }
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-
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fputs ("\t.localentry\t", file);
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assemble_name (file, name);
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fputs (",.-", file);
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assemble_name (file, name);
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fputs ("\n", file);
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/* Emit the nops after local entry. */
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- if (patch_area_size > 0)
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- rs6000_print_patchable_function_entry (file, patch_area_size,
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- patch_area_entry == 0);
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+ unsigned short patch_area_size = crtl->patch_area_size;
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+ unsigned short patch_area_entry = crtl->patch_area_entry;
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+ if (patch_area_size > patch_area_entry)
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+ {
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+ cfun->machine->stop_patch_area_print = false;
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+ patch_area_size -= patch_area_entry;
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+ rs6000_print_patchable_function_entry (file, patch_area_size,
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+ patch_area_entry == 0);
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+ }
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}
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else if (rs6000_pcrel_p ())
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diff --git a/gcc/config/rs6000/rs6000.cc b/gcc/config/rs6000/rs6000.cc
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index 2b876c90e6f..a08ed7466dd 100644
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--- a/gcc/config/rs6000/rs6000.cc
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+++ b/gcc/config/rs6000/rs6000.cc
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@@ -14936,12 +14936,14 @@ rs6000_print_patchable_function_entry (FILE *file,
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bool record_p)
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{
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bool global_entry_needed_p = rs6000_global_entry_point_prologue_needed_p ();
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- /* For a function which needs global entry point, we will emit the
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- patchable area before and after local entry point under the control of
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- cfun->machine->global_entry_emitted, see the handling in function
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+ /* For a function which needs global entry point, we will only emit the
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+ patchable area after local entry point under the control of
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+ !cfun->machine->stop_patch_area_print, see the handling in functions
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rs6000_output_function_prologue. */
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- if (!global_entry_needed_p || cfun->machine->global_entry_emitted)
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+ if (!cfun->machine->stop_patch_area_print)
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default_print_patchable_function_entry (file, patch_area_size, record_p);
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+ else
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+ gcc_assert (global_entry_needed_p);
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}
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enum rtx_code
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@@ -21115,6 +21117,11 @@ rs6000_elf_declare_function_name (FILE *file, const char *name, tree decl)
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fprintf (file, "\t.previous\n");
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}
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ASM_OUTPUT_LABEL (file, name);
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+ /* At this time, the "before" NOPs have been already emitted,
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+ let's stop generic code from printing the "after" NOPs and
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+ emit just after local entry later. */
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+ if (rs6000_global_entry_point_prologue_needed_p ())
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+ cfun->machine->stop_patch_area_print = true;
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}
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static void rs6000_elf_file_end (void) ATTRIBUTE_UNUSED;
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diff --git a/gcc/config/rs6000/rs6000.h b/gcc/config/rs6000/rs6000.h
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index 9f02025b0c8..ebe97beb182 100644
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--- a/gcc/config/rs6000/rs6000.h
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+++ b/gcc/config/rs6000/rs6000.h
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@@ -2437,10 +2437,12 @@ typedef struct GTY(()) machine_function
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bool lr_is_wrapped_separately;
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bool toc_is_wrapped_separately;
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bool mma_return_type_error;
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- /* Indicate global entry is emitted, only useful when the function requires
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- global entry. It helps to control the patchable area before and after
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- local entry. */
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- bool global_entry_emitted;
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+ /* With ELFv2 ABI dual entry points being adopted, generic framework
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+ targetm.asm_out.print_patchable_function_entry would generate "after"
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+ NOPs before local entry, it is wrong. This flag is to stop it from
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+ printing patch area before local entry, it is only useful when the
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+ function requires dual entry points. */
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+ bool stop_patch_area_print;
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} machine_function;
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#endif
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diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
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index b17d0cf9341..0cdc5ac8c61 100644
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--- a/gcc/doc/invoke.texi
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+++ b/gcc/doc/invoke.texi
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@@ -17449,11 +17449,11 @@ If @code{N=0}, no pad location is recorded.
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The NOP instructions are inserted at---and maybe before, depending on
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@var{M}---the function entry address, even before the prologue. On
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PowerPC with the ELFv2 ABI, for a function with dual entry points,
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-the local entry point is this function entry address.
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+@var{M} NOP instructions are inserted before the global entry point and
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+@var{N} - @var{M} NOP instructions are inserted after the local entry
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+point, which means the NOP instructions may not be consecutive.
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-The maximum value of @var{N} and @var{M} is 65535. On PowerPC with the
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-ELFv2 ABI, for a function with dual entry points, the supported values
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-for @var{M} are 0, 2, 6 and 14.
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+The maximum value of @var{N} and @var{M} is 65535.
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@end table
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diff --git a/gcc/testsuite/c-c++-common/patchable_function_entry-default.c b/gcc/testsuite/c-c++-common/patchable_function_entry-default.c
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index 3ccbafc87db..899938b4aa3 100644
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--- a/gcc/testsuite/c-c++-common/patchable_function_entry-default.c
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+++ b/gcc/testsuite/c-c++-common/patchable_function_entry-default.c
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@@ -1,9 +1,6 @@
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/* { dg-do compile { target { ! { nvptx*-*-* visium-*-* } } } } */
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/* { dg-options "-O2 -fpatchable-function-entry=3,1" } */
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/* { dg-additional-options "-fno-pie" { target sparc*-*-* } } */
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-/* See PR99888, one single preceding nop isn't allowed on powerpc_elfv2,
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- so overriding with two preceding nops to make it pass there. */
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-/* { dg-additional-options "-fpatchable-function-entry=3,2" { target powerpc_elfv2 } } */
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/* { dg-final { scan-assembler-times "nop|NOP|SWYM" 3 { target { ! { alpha*-*-* riscv*-*-* } } } } } */
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/* { dg-final { scan-assembler-times "bis" 3 { target alpha*-*-* } } } */
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/* { dg-final { scan-assembler-times "nop\n" 3 { target riscv*-*-* } } } */
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diff --git a/gcc/testsuite/gcc.target/powerpc/pr99888-4.c b/gcc/testsuite/gcc.target/powerpc/pr99888-4.c
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index 00a8d4d316e..6f23f2bb939 100644
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--- a/gcc/testsuite/gcc.target/powerpc/pr99888-4.c
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+++ b/gcc/testsuite/gcc.target/powerpc/pr99888-4.c
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@@ -2,12 +2,10 @@
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/* There is no global entry point prologue with pcrel. */
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/* { dg-options "-mno-pcrel -fpatchable-function-entry=1,1" } */
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-/* Verify one error emitted for unexpected 1 nop before local
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- entry. */
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+/* Verify there is no error with 1 nop before local entry. */
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extern int a;
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int test (int b) {
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return a + b;
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}
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-/* { dg-error "unsupported number of nops before function entry \\(1\\)" "" { target *-*-* } .-1 } */
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diff --git a/gcc/testsuite/gcc.target/powerpc/pr99888-5.c b/gcc/testsuite/gcc.target/powerpc/pr99888-5.c
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index 39d3b4465f1..13f192ebd20 100644
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--- a/gcc/testsuite/gcc.target/powerpc/pr99888-5.c
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+++ b/gcc/testsuite/gcc.target/powerpc/pr99888-5.c
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@@ -2,12 +2,10 @@
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/* There is no global entry point prologue with pcrel. */
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/* { dg-options "-mno-pcrel -fpatchable-function-entry=7,3" } */
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-/* Verify one error emitted for unexpected 3 nops before local
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- entry. */
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+/* Verify no error emitted for 3 nops before local entry. */
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extern int a;
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int test (int b) {
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return a + b;
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}
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-/* { dg-error "unsupported number of nops before function entry \\(3\\)" "" { target *-*-* } .-1 } */
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diff --git a/gcc/testsuite/gcc.target/powerpc/pr99888-6.c b/gcc/testsuite/gcc.target/powerpc/pr99888-6.c
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index c6c18dcc7ac..431c69cae9a 100644
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--- a/gcc/testsuite/gcc.target/powerpc/pr99888-6.c
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+++ b/gcc/testsuite/gcc.target/powerpc/pr99888-6.c
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@@ -2,8 +2,7 @@
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/* There is no global entry point prologue with pcrel. */
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/* { dg-options "-mno-pcrel" } */
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-/* Verify one error emitted for unexpected 4 nops before local
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- entry. */
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+/* Verify no error emitted for 4 nops before local entry. */
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extern int a;
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@@ -11,4 +10,3 @@ __attribute__ ((patchable_function_entry (20, 4)))
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int test (int b) {
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return a + b;
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}
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-/* { dg-error "unsupported number of nops before function entry \\(4\\)" "" { target *-*-* } .-1 } */
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--
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2.45.2
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