From 17e116a7d1501a46cf4e45ec181148dc6a1e3e2b Mon Sep 17 00:00:00 2001 From: Alan Hayward Date: Fri, 22 Mar 2019 10:41:15 +0000 Subject: [PATCH] AArch64: Prologue scan unwinder support for signed return addresses Pauth address signing is enabled at binary compile time. When enabled the return addresses for functions may be mangled. This patch adds functionality to restore the original address for use in the prologue scan unwinder. In the prologue analyzer, check for PACIASP/PACIBSP (enable address mangling) and AUTIASP/AUTIBSP (disable address mangling). When unwinding the PC from the prologue, unmask the register if required. Add a test case to the prologue tests. gdb/ChangeLog: * aarch64-tdep.c (aarch64_analyze_prologue): Check for pauth instructions. (aarch64_analyze_prologue_test): Add PACIASP test. (aarch64_prologue_prev_register): Unmask PC value. --- gdb/ChangeLog | 8 +++++ gdb/aarch64-tdep.c | 89 ++++++++++++++++++++++++++++++++++++++++++---- 2 files changed, 91 insertions(+), 6 deletions(-) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 13b117205d..c23881976c 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,11 @@ +2019-03-22 Alan Hayward + Jiong Wang + + * aarch64-tdep.c (aarch64_analyze_prologue): Check for pauth + instructions. + (aarch64_analyze_prologue_test): Add PACIASP test. + (aarch64_prologue_prev_register): Unmask PC value. + 2019-03-22 Alan Hayward Jiong Wang diff --git a/gdb/aarch64-tdep.c b/gdb/aarch64-tdep.c index 07430c0f25..247d0ed4c6 100644 --- a/gdb/aarch64-tdep.c +++ b/gdb/aarch64-tdep.c @@ -476,6 +476,37 @@ aarch64_analyze_prologue (struct gdbarch *gdbarch, /* Stop analysis on branch. */ break; } + else if (inst.opcode->iclass == ic_system) + { + struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); + int ra_state_val = 0; + + if (insn == 0xd503233f /* paciasp. */ + || insn == 0xd503237f /* pacibsp. */) + { + /* Return addresses are mangled. */ + ra_state_val = 1; + } + else if (insn == 0xd50323bf /* autiasp. */ + || insn == 0xd50323ff /* autibsp. */) + { + /* Return addresses are not mangled. */ + ra_state_val = 0; + } + else + { + if (aarch64_debug) + debug_printf ("aarch64: prologue analysis gave up addr=%s" + " opcode=0x%x (iclass)\n", + core_addr_to_string_nz (start), insn); + break; + } + + if (tdep->has_pauth () && cache != nullptr) + trad_frame_set_value (cache->saved_regs, + tdep->pauth_ra_state_regnum, + ra_state_val); + } else { if (aarch64_debug) @@ -582,11 +613,13 @@ aarch64_analyze_prologue_test (void) struct gdbarch *gdbarch = gdbarch_find_by_info (info); SELF_CHECK (gdbarch != NULL); + struct aarch64_prologue_cache cache; + cache.saved_regs = trad_frame_alloc_saved_regs (gdbarch); + + struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); + /* Test the simple prologue in which frame pointer is used. */ { - struct aarch64_prologue_cache cache; - cache.saved_regs = trad_frame_alloc_saved_regs (gdbarch); - static const uint32_t insns[] = { 0xa9af7bfd, /* stp x29, x30, [sp,#-272]! */ 0x910003fd, /* mov x29, sp */ @@ -622,9 +655,6 @@ aarch64_analyze_prologue_test (void) /* Test a prologue in which STR is used and frame pointer is not used. */ { - struct aarch64_prologue_cache cache; - cache.saved_regs = trad_frame_alloc_saved_regs (gdbarch); - static const uint32_t insns[] = { 0xf81d0ff3, /* str x19, [sp, #-48]! */ 0xb9002fe0, /* str w0, [sp, #44] */ @@ -664,6 +694,45 @@ aarch64_analyze_prologue_test (void) == -1); } } + + /* Test a prologue in which there is a return address signing instruction. */ + if (tdep->has_pauth ()) + { + static const uint32_t insns[] = { + 0xd503233f, /* paciasp */ + 0xa9bd7bfd, /* stp x29, x30, [sp, #-48]! */ + 0x910003fd, /* mov x29, sp */ + 0xf801c3f3, /* str x19, [sp, #28] */ + 0xb9401fa0, /* ldr x19, [x29, #28] */ + }; + instruction_reader_test reader (insns); + + CORE_ADDR end = aarch64_analyze_prologue (gdbarch, 0, 128, &cache, + reader); + + SELF_CHECK (end == 4 * 4); + SELF_CHECK (cache.framereg == AARCH64_FP_REGNUM); + SELF_CHECK (cache.framesize == 48); + + for (int i = 0; i < AARCH64_X_REGISTER_COUNT; i++) + { + if (i == 19) + SELF_CHECK (cache.saved_regs[i].addr == -20); + else if (i == AARCH64_FP_REGNUM) + SELF_CHECK (cache.saved_regs[i].addr == -48); + else if (i == AARCH64_LR_REGNUM) + SELF_CHECK (cache.saved_regs[i].addr == -40); + else + SELF_CHECK (cache.saved_regs[i].addr == -1); + } + + if (tdep->has_pauth ()) + { + SELF_CHECK (trad_frame_value_p (cache.saved_regs, + tdep->pauth_ra_state_regnum)); + SELF_CHECK (cache.saved_regs[tdep->pauth_ra_state_regnum].addr == 1); + } + } } } // namespace selftests #endif /* GDB_SELF_TEST */ @@ -873,8 +942,16 @@ aarch64_prologue_prev_register (struct frame_info *this_frame, if (prev_regnum == AARCH64_PC_REGNUM) { CORE_ADDR lr; + struct gdbarch *gdbarch = get_frame_arch (this_frame); + struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); lr = frame_unwind_register_unsigned (this_frame, AARCH64_LR_REGNUM); + + if (tdep->has_pauth () + && trad_frame_value_p (cache->saved_regs, + tdep->pauth_ra_state_regnum)) + lr = aarch64_frame_unmask_address (tdep, this_frame, lr); + return frame_unwind_got_constant (this_frame, prev_regnum, lr); } -- 2.34.1