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rs6000: Error on CPUs and ABIs that don't support the ROP protection insns [PR114759]

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We currently silently ignore the -mrop-protect option for old CPUs we don't
support with the ROP hash insns, but we throw an error for unsupported ABIs.
This patch treats unsupported CPUs and ABIs similarly by throwing an error
both both.  This matches clang behavior and allows us to simplify our tests
in the code that generates our prologue and epilogue code.

2024-06-26  Peter Bergner  <bergner@linux.ibm.com>

gcc/
	PR target/114759
	* config/rs6000/rs6000.cc (rs6000_option_override_internal): Disallow
	CPUs and ABIs that do no support the ROP protection insns.
	* config/rs6000/rs6000-logue.cc (rs6000_stack_info): Remove now
	unneeded tests.
	(rs6000_emit_prologue): Likewise.
	Remove unneeded gcc_assert.
	(rs6000_emit_epilogue): Likewise.
	* config/rs6000/rs6000.md: Likewise.

gcc/testsuite/
	PR target/114759
	* gcc.target/powerpc/pr114759-3.c: New test.
This commit is contained in:
Peter Bergner 2024-07-15 16:57:32 -05:00
parent a05c3d23d1
commit 6f2bab9b5d
4 changed files with 39 additions and 18 deletions
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22
gcc/config/rs6000/rs6000-logue.cc
View File

@ -716,17 +716,11 @@ rs6000_stack_info (void)
info->calls_p = (!crtl->is_leaf || cfun->machine->ra_needs_full_frame);
info->rop_hash_size = 0;
if (TARGET_POWER8
&& info->calls_p
&& DEFAULT_ABI == ABI_ELFv2
&& rs6000_rop_protect)
/* If we want ROP protection and this function makes a call, indicate
we need to create a stack slot to save the hashed return address in. */
if (rs6000_rop_protect
&& info->calls_p)
info->rop_hash_size = 8;
else if (rs6000_rop_protect && DEFAULT_ABI != ABI_ELFv2)
{
/* We can't check this in rs6000_option_override_internal since
DEFAULT_ABI isn't established yet. */
error ("%qs requires the ELFv2 ABI", "-mrop-protect");
}
/* Determine if we need to save the condition code registers. */
if (save_reg_p (CR2_REGNO)
@ -3272,9 +3266,8 @@ rs6000_emit_prologue (void)
/* NOTE: The hashst isn't needed if we're going to do a sibcall,
but there's no way to know that here. Harmless except for
performance, of course. */
if (TARGET_POWER8 && rs6000_rop_protect && info->rop_hash_size != 0)
if (info->rop_hash_size)
{
gcc_assert (DEFAULT_ABI == ABI_ELFv2);
rtx stack_ptr = gen_rtx_REG (Pmode, STACK_POINTER_REGNUM);
rtx addr = gen_rtx_PLUS (Pmode, stack_ptr,
GEN_INT (info->rop_hash_save_offset));
@ -5051,12 +5044,9 @@ rs6000_emit_epilogue (enum epilogue_type epilogue_type)
/* The ROP hash check must occur after the stack pointer is restored
(since the hash involves r1), and is not performed for a sibcall. */
if (TARGET_POWER8
&& rs6000_rop_protect
&& info->rop_hash_size != 0
if (info->rop_hash_size
&& epilogue_type != EPILOGUE_TYPE_SIBCALL)
{
gcc_assert (DEFAULT_ABI == ABI_ELFv2);
rtx stack_ptr = gen_rtx_REG (Pmode, STACK_POINTER_REGNUM);
rtx addr = gen_rtx_PLUS (Pmode, stack_ptr,
GEN_INT (info->rop_hash_save_offset));

12
gcc/config/rs6000/rs6000.cc
View File

@ -4844,6 +4844,18 @@ rs6000_option_override_internal (bool global_init_p)
}
}
/* We only support ROP protection on certain targets. */
if (rs6000_rop_protect)
{
/* Disallow CPU targets we don't support. */
if (!TARGET_POWER8)
error ("%<-mrop-protect%> requires %<-mcpu=power8%> or later");
/* Disallow ABI targets we don't support. */
if (DEFAULT_ABI != ABI_ELFv2)
error ("%<-mrop-protect%> requires the ELFv2 ABI");
}
/* Initialize all of the registers. */
rs6000_init_hard_regno_mode_ok (global_init_p);

4
gcc/config/rs6000/rs6000.md
View File

@ -15810,7 +15810,7 @@
[(set (match_operand:DI 0 "simple_offsettable_mem_operand" "=m")
(unspec_volatile:DI [(match_operand:DI 1 "int_reg_operand" "r")]
UNSPEC_HASHST))]
"TARGET_POWER8 && rs6000_rop_protect"
"rs6000_rop_protect"
{
static char templ[32];
const char *p = rs6000_privileged ? "p" : "";
@ -15823,7 +15823,7 @@
[(unspec_volatile [(match_operand:DI 0 "int_reg_operand" "r")
(match_operand:DI 1 "simple_offsettable_mem_operand" "m")]
UNSPEC_HASHCHK)]
"TARGET_POWER8 && rs6000_rop_protect"
"rs6000_rop_protect"
{
static char templ[32];
const char *p = rs6000_privileged ? "p" : "";

19
gcc/testsuite/gcc.target/powerpc/pr114759-3.c Normal file
View File

@ -0,0 +1,19 @@
/* PR target/114759 */
/* { dg-do compile } */
/* { dg-options "-O2 -mdejagnu-cpu=power7 -mrop-protect" } */
/* Verify we emit an error if we use -mrop-protect with an unsupported cpu. */
extern void foo (void);
int
bar (void)
{
foo ();
return 5;
}
/* The correct line number is in the preamble to the error message, not
in the final line (which is all that dg-error inspects). Hence, we have
to tell dg-error to ignore the line number. */
/* { dg-error "'-mrop-protect' requires '-mcpu=power8'" "PR114759" { target *-*-* } 0 } */