| Message ID | 20240105191240.3646771-1-goldstein.w.n@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | x86: Fixup some nits in longjmp asm implementation | expand |
On Fri, Jan 5, 2024 at 11:12 AM Noah Goldstein <goldstein.w.n@gmail.com> wrote: > > Replace a stray `nop` with a `.p2align` directive. > --- > .../unix/sysv/linux/x86_64/____longjmp_chk.S | 2 +- > sysdeps/x86_64/dl-machine.h | 31 +++++++++---------- > 2 files changed, 16 insertions(+), 17 deletions(-) > > diff --git a/sysdeps/unix/sysv/linux/x86_64/____longjmp_chk.S b/sysdeps/unix/sysv/linux/x86_64/____longjmp_chk.S > index 9aa24620b9..9d9732afdc 100644 > --- a/sysdeps/unix/sysv/linux/x86_64/____longjmp_chk.S > +++ b/sysdeps/unix/sysv/linux/x86_64/____longjmp_chk.S > @@ -57,8 +57,8 @@ longjmp_msg: > cfi_def_cfa_offset(16); \ > LOAD_MSG; \ > call HIDDEN_JUMPTARGET(__fortify_fail); \ > - nop; \ > cfi_restore_state; \ > + .p2align 3, 5; \ > .Lok2: \ > movq %r10, %rdi; \ > cfi_restore (%rdi); \ > diff --git a/sysdeps/x86_64/dl-machine.h b/sysdeps/x86_64/dl-machine.h > index adcc0f7113..7ef6e24eb5 100644 > --- a/sysdeps/x86_64/dl-machine.h > +++ b/sysdeps/x86_64/dl-machine.h > @@ -618,25 +618,24 @@ x86_64_rewrite_plt (struct link_map *map, ElfW(Addr) plt_rewrite) > if (((uint64_t) disp + (uint64_t) ((uint32_t) INT32_MIN)) > <= (uint64_t) UINT32_MAX) > { > - pad = branch_start + JMP32_INSN_SIZE; > + pad = branch_start + JMP32_INSN_SIZE; These changes are unrelated. > - if (__glibc_unlikely (pad > plt_end)) > - continue; > + if (__glibc_unlikely (pad > plt_end)) > + continue; > > - /* If the target branch can be reached with a direct branch, > - rewrite the PLT entry with a direct branch. */ > - if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_BINDINGS)) > - { > - const char *sym_name = x86_64_reloc_symbol_name (map, > - reloc); > - _dl_debug_printf ("changing '%s' PLT entry in '%s' to " > - "direct branch\n", sym_name, > - DSO_FILENAME (map->l_name)); > - } > + /* If the target branch can be reached with a direct branch, > + rewrite the PLT entry with a direct branch. */ > + if (__glibc_unlikely (GLRO (dl_debug_mask) & DL_DEBUG_BINDINGS)) > + { > + const char *sym_name = x86_64_reloc_symbol_name (map, reloc); > + _dl_debug_printf ("changing '%s' PLT entry in '%s' to " > + "direct branch\n", > + sym_name, DSO_FILENAME (map->l_name)); > + } > > - /* Write out direct branch. */ > - *(uint8_t *) branch_start = JMP32_INSN_OPCODE; > - *((uint32_t *) (branch_start + 1)) = disp; > + /* Write out direct branch. */ > + *(uint8_t *) branch_start = JMP32_INSN_OPCODE; > + *((uint32_t *) (branch_start + 1)) = disp; > } > else > { > -- > 2.34.1 >
diff --git a/sysdeps/unix/sysv/linux/x86_64/____longjmp_chk.S b/sysdeps/unix/sysv/linux/x86_64/____longjmp_chk.S index 9aa24620b9..9d9732afdc 100644 --- a/sysdeps/unix/sysv/linux/x86_64/____longjmp_chk.S +++ b/sysdeps/unix/sysv/linux/x86_64/____longjmp_chk.S @@ -57,8 +57,8 @@ longjmp_msg: cfi_def_cfa_offset(16); \ LOAD_MSG; \ call HIDDEN_JUMPTARGET(__fortify_fail); \ - nop; \ cfi_restore_state; \ + .p2align 3, 5; \ .Lok2: \ movq %r10, %rdi; \ cfi_restore (%rdi); \ diff --git a/sysdeps/x86_64/dl-machine.h b/sysdeps/x86_64/dl-machine.h index adcc0f7113..7ef6e24eb5 100644 --- a/sysdeps/x86_64/dl-machine.h +++ b/sysdeps/x86_64/dl-machine.h @@ -618,25 +618,24 @@ x86_64_rewrite_plt (struct link_map *map, ElfW(Addr) plt_rewrite) if (((uint64_t) disp + (uint64_t) ((uint32_t) INT32_MIN)) <= (uint64_t) UINT32_MAX) { - pad = branch_start + JMP32_INSN_SIZE; + pad = branch_start + JMP32_INSN_SIZE; - if (__glibc_unlikely (pad > plt_end)) - continue; + if (__glibc_unlikely (pad > plt_end)) + continue; - /* If the target branch can be reached with a direct branch, - rewrite the PLT entry with a direct branch. */ - if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_BINDINGS)) - { - const char *sym_name = x86_64_reloc_symbol_name (map, - reloc); - _dl_debug_printf ("changing '%s' PLT entry in '%s' to " - "direct branch\n", sym_name, - DSO_FILENAME (map->l_name)); - } + /* If the target branch can be reached with a direct branch, + rewrite the PLT entry with a direct branch. */ + if (__glibc_unlikely (GLRO (dl_debug_mask) & DL_DEBUG_BINDINGS)) + { + const char *sym_name = x86_64_reloc_symbol_name (map, reloc); + _dl_debug_printf ("changing '%s' PLT entry in '%s' to " + "direct branch\n", + sym_name, DSO_FILENAME (map->l_name)); + } - /* Write out direct branch. */ - *(uint8_t *) branch_start = JMP32_INSN_OPCODE; - *((uint32_t *) (branch_start + 1)) = disp; + /* Write out direct branch. */ + *(uint8_t *) branch_start = JMP32_INSN_OPCODE; + *((uint32_t *) (branch_start + 1)) = disp; } else {