From c01660c625766e848195285cc20581b9ed7ecfe2 Mon Sep 17 00:00:00 2001 From: Andrew Burgess Date: Wed, 17 Apr 2019 00:31:43 +0100 Subject: [PATCH] gdb/riscv: Allow breakpoints to be created at invalid addresses Some testsuite cases (gdb.cp/nsalias.exp for example) construct dwarf2 debug info for fake functions to test that this debug info is handled correctly. We currently get an error trying to read from an invalid address while creating breakpoints for these fake functions. Other targets allow creating breakpoints on invalid addresses, and only error when GDB actually tries to insert the breakpoints. In order to make RISC-V behave in the same way as other targets, this commit makes the failure to read memory during breakpoint creation non-fatal, we then expect to see a failure when GDB tries to insert the breakpoint, just like other targets. Tested with a riscv64-linux native testsuite run. gdb/ChangeLog: * riscv-tdep.c (riscv_breakpoint_kind_from_pc): Hanndle case where code read might fail, assume 4-byte breakpoint in that case. --- gdb/ChangeLog | 6 ++++++ gdb/riscv-tdep.c | 10 +++++++++- 2 files changed, 15 insertions(+), 1 deletion(-) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index ba1300d57ef..f8120db4c74 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,9 @@ +2019-04-17 Jim Wilson + Andrew Burgess + + * riscv-tdep.c (riscv_breakpoint_kind_from_pc): Hanndle case where + code read might fail, assume 4-byte breakpoint in that case. + 2019-04-15 Leszek Swirski * amd64-tdep.c (amd64_classify_aggregate): Use cp_pass_by_reference diff --git a/gdb/riscv-tdep.c b/gdb/riscv-tdep.c index 6370bc268fc..4fe07ef4375 100644 --- a/gdb/riscv-tdep.c +++ b/gdb/riscv-tdep.c @@ -430,7 +430,15 @@ riscv_breakpoint_kind_from_pc (struct gdbarch *gdbarch, CORE_ADDR *pcptr) unaligned_p = true; else { - /* Read the opcode byte to determine the instruction length. */ + /* Read the opcode byte to determine the instruction length. If + the read fails this may be because we tried to set the + breakpoint at an invalid address, in this case we provide a + fake result which will give a breakpoint length of 4. + Hopefully when we try to actually insert the breakpoint we + will see a failure then too which will be reported to the + user. */ + if (target_read_code (*pcptr, buf, 1) == -1) + buf[0] = 0; read_code (*pcptr, buf, 1); } -- 2.39.2