Commit 8679931c authored by Omair Javaid's avatar Omair Javaid
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Unset gdbarch significant_addr_bit by default

This patch fixes a bug introduced by fix to AArch64 pointer tagging.

In our fix for tagged pointer support our agreed approach was to sign
extend user-space address after clearing tag bits. This is not same
for all architectures and this patch allows sign extension for
addresses on targets which specifically set significant_addr_bit.

More information about patch that caused the issues and discussion
around tagged pointer support can be found in links below:

https://sourceware.org/ml/gdb-patches/2018-05/msg00000.html
https://sourceware.org/ml/gdb-patches/2017-12/msg00159.html

gdb/ChangeLog:

2018-05-31  Omair Javaid  <omair.javaid@linaro.org>

	PR gdb/23210
	* gdbarch.sh (significant_addr_bit): Default to zero when
	not set by target architecture.
	* gdbarch.c: Re-generated.
	* utils.c (address_significant): Update.
parent fcfc3b91
2018-05-31 Omair Javaid <omair.javaid@linaro.org>
PR gdb/23210
* gdbarch.sh (significant_addr_bit): Default to zero when
not set by target architecture.
* gdbarch.c: Re-generated.
* utils.c (address_significant): Update.
2018-05-10 Joel Brobecker <brobecker@adacore.com>
PR server/23158:
......
......@@ -619,8 +619,7 @@ verify_gdbarch (struct gdbarch *gdbarch)
/* Skip verify of stabs_argument_has_addr, invalid_p == 0 */
/* Skip verify of convert_from_func_ptr_addr, invalid_p == 0 */
/* Skip verify of addr_bits_remove, invalid_p == 0 */
if (gdbarch->significant_addr_bit == 0)
gdbarch->significant_addr_bit = gdbarch_addr_bit (gdbarch);
/* Skip verify of significant_addr_bit, invalid_p == 0 */
/* Skip verify of software_single_step, has predicate. */
/* Skip verify of single_step_through_delay, has predicate. */
/* Skip verify of print_insn, invalid_p == 0 */
......@@ -3225,6 +3224,7 @@ int
gdbarch_significant_addr_bit (struct gdbarch *gdbarch)
{
gdb_assert (gdbarch != NULL);
/* Skip verify of significant_addr_bit, invalid_p == 0 */
if (gdbarch_debug >= 2)
fprintf_unfiltered (gdb_stdlog, "gdbarch_significant_addr_bit called\n");
return gdbarch->significant_addr_bit;
......
......@@ -625,7 +625,7 @@ m;CORE_ADDR;addr_bits_remove;CORE_ADDR addr;addr;;core_addr_identity;;0
# For example, on AArch64, the top bits of an address known as the "tag"
# are ignored by the kernel, the hardware, etc. and can be regarded as
# additional data associated with the address.
v;int;significant_addr_bit;;;;;gdbarch_addr_bit (gdbarch);
v;int;significant_addr_bit;;;;;;0
# FIXME/cagney/2001-01-18: This should be split in two. A target method that
# indicates if the target needs software single step. An ISA method to
......
......@@ -2733,10 +2733,11 @@ address_significant (gdbarch *gdbarch, CORE_ADDR addr)
/* Clear insignificant bits of a target address and sign extend resulting
address, avoiding shifts larger or equal than the width of a CORE_ADDR.
The local variable ADDR_BIT stops the compiler reporting a shift overflow
when it won't occur. */
when it won't occur. Skip updating of target address if current target
has not set gdbarch significant_addr_bit. */
int addr_bit = gdbarch_significant_addr_bit (gdbarch);
if (addr_bit < (sizeof (CORE_ADDR) * HOST_CHAR_BIT))
if (addr_bit && (addr_bit < (sizeof (CORE_ADDR) * HOST_CHAR_BIT)))
{
CORE_ADDR sign = (CORE_ADDR) 1 << (addr_bit - 1);
addr &= ((CORE_ADDR) 1 << addr_bit) - 1;
......
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