From fad101b3f27e7fde7fa63da5817eecfa6354adf0 Mon Sep 17 00:00:00 2001 From: Michal Meloun Date: Tue, 27 Feb 2018 15:35:11 +0000 Subject: [PATCH] Make rtld_bind_start() debugger friendly. Save link register and annotate call frame structure so debugger can unwind call frame created by rtld_bind_start(). MFC after: 2 weeks --- libexec/rtld-elf/aarch64/rtld_start.S | 20 +++++++++++++++----- 1 file changed, 15 insertions(+), 5 deletions(-) diff --git a/libexec/rtld-elf/aarch64/rtld_start.S b/libexec/rtld-elf/aarch64/rtld_start.S index 41397f944911..b9577dfccd75 100644 --- a/libexec/rtld-elf/aarch64/rtld_start.S +++ b/libexec/rtld-elf/aarch64/rtld_start.S @@ -55,7 +55,15 @@ END(.rtld_start) * x17 = &_rtld_bind_start */ ENTRY(_rtld_bind_start) + .cfi_startproc mov x17, sp + + /* Save frame pointer and SP */ + stp x29, x30, [sp, #-16]! + mov x29, sp + .cfi_def_cfa x29, 16 + .cfi_offset x30, -8 + .cfi_offset x29, -16 /* Save the arguments */ stp x0, x1, [sp, #-16]! @@ -84,9 +92,6 @@ ENTRY(_rtld_bind_start) /* Call into rtld */ bl _rtld_bind - /* Restore the registers saved by the plt code */ - ldp xzr, x30, [sp, #(5 * 16 + 4 * 32)] - /* Backup the address to branch to */ mov x16, x0 @@ -100,11 +105,16 @@ ENTRY(_rtld_bind_start) ldp x4, x5, [sp], #16 ldp x2, x3, [sp], #16 ldp x0, x1, [sp], #16 - /* And the part of the stack the plt entry handled */ - add sp, sp, #16 + + /* Restore frame pointer */ + ldp x29, xzr, [sp], #16 + + /* Restore link register saved by the plt code */ + ldp xzr, x30, [sp], #16 /* Call into the correct function */ br x16 + .cfi_endproc END(_rtld_bind_start) /*