Changeset eb630cf in mainline

Timestamp:

2023-01-18T20:20:29Z (16 months ago)

Author:

Jiří Zárevúcky <zarevucky.jiri@…>

Branches:

master, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

b67ce1ff

Parents:

b83c5e4

git-author:

Jiří Zárevúcky <zarevucky.jiri@…> (2022-09-02 18:43:01)

git-committer:

Jiří Zárevúcky <zarevucky.jiri@…> (2023-01-18 20:20:29)

Message:

Fix handling of ABS32 relocation on arm32

A bad symbol reference in entryjmp.S was creating
an ABS32 relocation causing issues for dynamic
linker, leading to the ABS32 relocation being
generally ignored. However, that was not the
correct solution, as doing so breaks stacktrace
code (which emits global function pointers in
static data, creating ABS32 relocs).

The symbol reference in entryjmp.S was fixed by
converting the function to inline assembly, let
GCC deal with variable addresses.

Location:

uspace/lib/c/arch/arm32

Files:

• meson.build (modified) (1 diff)
• src/atomic.c (modified) (1 diff)
• src/crt0.S (modified) (1 diff)
• src/entryjmp.S (deleted)
• src/entryjmp.c (added)
• src/ras_page.h (added)
• src/rtld/reloc.c (modified) (2 diffs)

uspace/lib/c/arch/arm32/meson.build

@@ -30 +30 @@
 arch_src += files(
         'src/atomic.c',
-        'src/entryjmp.S',
+        'src/entryjmp.c',
         'src/thread_entry.S',
         'src/syscall.c',

uspace/lib/c/arch/arm32/src/atomic.c

@@ -34 +34 @@
 
 #include <stdbool.h>
+#include "ras_page.h"
 
 volatile unsigned *ras_page;

uspace/lib/c/arch/arm32/src/crt0.S

@@ -40 +40 @@
 SYMBOL(_start)
         # Store the RAS page address into the ras_page variable
+        // FIXME: This only works for not-PIC executables.
         ldr r0, =ras_page
         str r2, [r0]

uspace/lib/c/arch/arm32/src/rtld/reloc.c

@@ -127 +127 @@
 
                 switch (rel_type) {
-                case R_ARM_ABS32:
-                        DPRINTF("ignore R_ARM_ABS32\n");
-                        /*
-                         * Not sure why we get these static relocations, but
-                         * attempting to process them will crash the
-                         * loader. If we ignore them, everything
-                         * seems to work.
-                         */
-                        break;
-
                 case R_ARM_TLS_DTPMOD32:
                         DPRINTF("fixup R_ARM_TLS_DTPMOD32\n");
@@ -189 +179 @@
                 case R_ARM_GLOB_DAT:
                 case R_ARM_JUMP_SLOT:
-                        DPRINTF("fixup R_ARM_GLOB_DAT/JUMP_SLOT (S)\n");
+                case R_ARM_ABS32:
+                        DPRINTF("fixup R_ARM_GLOB_DAT/JUMP_SLOT/ABS32 (S)\n");
                         *r_ptr = sym_addr;
                         break;