From 1a9f72a7a8f445b8d665eb36b053a18e758e63e6 Mon Sep 17 00:00:00 2001 From: Jozef Lawrynowicz Date: Wed, 5 Aug 2020 12:55:07 +0100 Subject: [PATCH] MSP430: ld: Update output section tail when shuffling ".either" sections The MSP430 linker shuffles input sections with names beginning with ".either" between the upper and lower memory regions, to try to avoid one region overflowing when there is space in the other region. However, when an ".either" input section attached to the tail of an output section was moved to a different output section in the other region, that tail wasn't being updated to the new section at the end of the original output section. This caused a bug where a shuffled section could end up in the middle of another section in the output executable, resulting in corrupted code or data. When changing the output section of an input section attached to the tail of its output section, that tail is now updated to point to the new input section at the end of the section list. ld/ChangeLog: 2020-08-06 Jozef Lawrynowicz * emultempl/msp430.em (change_output_section): Update the tail of the output section statement list when moving the original tail to a different output section. (eval_upper_either_sections): Don't move sections from the upper region to the lower region unless the upper region is overflowing. --- ld/ChangeLog | 9 +++++++++ ld/emultempl/msp430.em | 32 ++++++++++++++++++++++---------- 2 files changed, 31 insertions(+), 10 deletions(-) diff --git a/ld/ChangeLog b/ld/ChangeLog index 0a574db7b03..b4134184714 100644 --- a/ld/ChangeLog +++ b/ld/ChangeLog @@ -1,3 +1,12 @@ +2020-08-06 Jozef Lawrynowicz + + * emultempl/msp430.em (change_output_section): Update the tail + of the output section statement list when moving the original + tail to a different output section. + (eval_upper_either_sections): Don't move sections from the upper + region to the lower region unless the upper region is + overflowing. + 2020-08-03 Alan Modra * ldlex.l (yy_create_string_buffer): Use xmalloc rather than malloc. diff --git a/ld/emultempl/msp430.em b/ld/emultempl/msp430.em index c823a6d9b58..2a840c1e2bf 100644 --- a/ld/emultempl/msp430.em +++ b/ld/emultempl/msp430.em @@ -339,9 +339,10 @@ fi fragment <input_section.section; if (is == s) { + lang_statement_list_type *old_list + = (lang_statement_list_type *) &old_os->children; s->output_section = NULL; - lang_add_section (& (new_output_section->children), s, NULL, - new_output_section); + lang_add_section (&new_os->children, s, NULL, new_os); + /* Remove the section from the old output section. */ if (prev == NULL) *head = curr->header.next; else prev->header.next = curr->header.next; + /* If the input section we just moved is the tail of the old + output section, then we also need to adjust that tail. */ + if (old_list->tail == (lang_statement_union_type **) curr) + old_list->tail = (lang_statement_union_type **) prev; + return TRUE; } break; case lang_wild_statement_enum: if (change_output_section (&(curr->wild_statement.children.head), - s, new_output_section)) + s, new_os, old_os)) return TRUE; break; default: @@ -606,11 +614,15 @@ eval_upper_either_sections (bfd *abfd ATTRIBUTE_UNUSED, upper_size = &upper_size_ram; } - /* Move sections in the upper region that would fit in the lower - region to the lower region. */ - if (*lower_size + s->size < lower->region->length) + /* If the upper region is overflowing, try moving sections to the lower + region. + Note that there isn't any general benefit to using lower memory over upper + memory, so we only move sections around with the goal of making the program + fit. */ + if (*upper_size > upper->region->length + && *lower_size + s->size < lower->region->length) { - if (change_output_section (&(upper->children.head), s, lower)) + if (change_output_section (&(upper->children.head), s, lower, upper)) { *upper_size -= s->size; *lower_size += s->size; @@ -700,7 +712,7 @@ eval_lower_either_sections (bfd *abfd ATTRIBUTE_UNUSED, } /* Move sections that cause the lower region to overflow to the upper region. */ if (*lower_size + s->size > output_sec->region->length) - change_output_section (&(output_sec->children.head), s, upper); + change_output_section (&(output_sec->children.head), s, upper, output_sec); else *lower_size += s->size; end: -- 2.30.2