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dynamic: add support for ELF packed relocations (relr)

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fincs 2024-08-31 00:40:56 +02:00
parent d66e3aa487
commit 8cff58d5af
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GPG Key ID: 62C7609ADA219C60
2 changed files with 39 additions and 1 deletions
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38
nx/source/runtime/dynamic.c
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@ -36,6 +36,10 @@ static void _dynProcessRela(uintptr_t base, const Elf64_Rela* rela, size_t relas
break;
}
case R_AARCH64_NONE: {
break;
}
case R_AARCH64_RELATIVE: {
u64* ptr = (u64*)(base + rela->r_offset);
*ptr = base + rela->r_addend;
@ -45,6 +49,25 @@ static void _dynProcessRela(uintptr_t base, const Elf64_Rela* rela, size_t relas
}
}
static void _dynProcessRelr(uintptr_t base, const Elf64_Relr* relr, size_t relrsz)
{
u64* ptr = NULL;
for (; relrsz--; relr++) {
if ((*relr & 1) == 0) {
ptr = (u64*)(base + *relr);
*ptr++ += base;
} else {
u64 bitmap = *relr >> 1;
while (bitmap) {
unsigned id = __builtin_ffsl(bitmap)-1;
bitmap &= ~(1UL << id);
ptr[id] += base;
}
ptr += 63;
}
}
}
void __nx_dynamic(uintptr_t base, const Mod0Header* mod0)
{
// Return early if MOD0 header has been invalidated
@ -65,6 +88,8 @@ void __nx_dynamic(uintptr_t base, const Mod0Header* mod0)
// Extract relevant information from the ELF dynamic section
const Elf64_Rela* rela = NULL;
size_t relasz = 0;
const Elf64_Relr* relr = NULL;
size_t relrsz = 0;
for (; dyn->d_tag != DT_NULL; dyn++) {
switch (dyn->d_tag) {
case DT_RELA:
@ -74,6 +99,14 @@ void __nx_dynamic(uintptr_t base, const Mod0Header* mod0)
case DT_RELASZ:
relasz = dyn->d_un.d_val / sizeof(Elf64_Rela);
break;
case DT_RELR:
relr = (const Elf64_Relr*)(base + dyn->d_un.d_ptr);
break;
case DT_RELRSZ:
relrsz = dyn->d_un.d_val / sizeof(Elf64_Relr);
break;
}
}
@ -82,6 +115,11 @@ void __nx_dynamic(uintptr_t base, const Mod0Header* mod0)
_dynProcessRela(base, rela, relasz);
}
// Apply RELR relocations if present
if (relr && relrsz) {
_dynProcessRelr(base, relr, relrsz);
}
// Return early if LNY0/LNY1 extensions are not present
if (mod0->magic_lny0 != 0x30594e4c || mod0->magic_lny1 != 0x31594e4c) { // LNY0, LNY1
return;

2
nx/switch.specs
View File

@ -1,5 +1,5 @@
*link:
+ -T %:getenv(DEVKITPRO /libnx/switch.ld) -pie --no-dynamic-linker --spare-dynamic-tags=0 --gc-sections -z text -z now -z nodynamic-undefined-weak --build-id=sha1 --nx-module-name
+ -T %:getenv(DEVKITPRO /libnx/switch.ld) -pie --no-dynamic-linker --spare-dynamic-tags=0 --gc-sections -z text -z now -z nodynamic-undefined-weak -z pack-relative-relocs --build-id=sha1 --nx-module-name
*startfile:
crti%O%s crtbegin%O%s --require-defined=main