RISC-V: Add support for TLS stack protector canary access

gcc/
	* config/riscv/riscv-opts.h (stack_protector_guard): New enum.
	* config/riscv/riscv.c (riscv_option_override): Handle
	the new options.
	* config/riscv/riscv.md (stack_protect_set): New pattern to handle
	flexible stack protector guard settings.
	(stack_protect_set_<mode>): Ditto.
	(stack_protect_test): Ditto.
	(stack_protect_test_<mode>): Ditto.
	* config/riscv/riscv.opt (mstack-protector-guard=,
	mstack-protector-guard-reg=, mstack-protector-guard-offset=): New
	options.
	* doc/invoke.texi (Option Summary) [RISC-V Options]:
	Add -mstack-protector-guard=, -mstack-protector-guard-reg=, and
	-mstack-protector-guard-offset=.
	(RISC-V Options): Ditto.

Signed-off-by: cooper <cooper.qu@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>

gcc/config/riscv/riscv-opts.h

@@ -51,4 +51,10 @@ enum riscv_align_data {
   riscv_align_data_type_natural
 };
 
+/* Where to get the canary for the stack protector.  */
+enum stack_protector_guard {
+  SSP_TLS,			/* per-thread canary in TLS block */
+  SSP_GLOBAL			/* global canary */
+};
+
 #endif /* ! GCC_RISCV_OPTS_H */

gcc/config/riscv/riscv.c

@@ -4775,6 +4775,53 @@ riscv_option_override (void)
 	   " [%<-mriscv-attribute%>]");
 #endif
 
+  if (riscv_stack_protector_guard == SSP_GLOBAL
+      && global_options_set.x_riscv_stack_protector_guard_offset_str)
+    {
+      error ("incompatible options %<-mstack-protector-guard=global%> and "
+	     "%<-mstack-protector-guard-offset=%s%>",
+	     riscv_stack_protector_guard_offset_str);
+    }
+
+  if (riscv_stack_protector_guard == SSP_TLS
+      && !(global_options_set.x_riscv_stack_protector_guard_offset_str
+	   && global_options_set.x_riscv_stack_protector_guard_reg_str))
+    {
+      error ("both %<-mstack-protector-guard-offset%> and "
+	     "%<-mstack-protector-guard-reg%> must be used "
+	     "with %<-mstack-protector-guard=sysreg%>");
+    }
+
+  if (global_options_set.x_riscv_stack_protector_guard_reg_str)
+    {
+      const char *str = riscv_stack_protector_guard_reg_str;
+      int reg = decode_reg_name (str);
+
+      if (!IN_RANGE (reg, GP_REG_FIRST + 1, GP_REG_LAST))
+	error ("%qs is not a valid base register in %qs", str,
+	       "-mstack-protector-guard-reg=");
+
+      riscv_stack_protector_guard_reg = reg;
+    }
+
+  if (global_options_set.x_riscv_stack_protector_guard_offset_str)
+    {
+      char *end;
+      const char *str = riscv_stack_protector_guard_offset_str;
+      errno = 0;
+      long offs = strtol (riscv_stack_protector_guard_offset_str, &end, 0);
+
+      if (!*str || *end || errno)
+	error ("%qs is not a valid number in %qs", str,
+	       "-mstack-protector-guard-offset=");
+
+      if (!SMALL_OPERAND (offs))
+	error ("%qs is not a valid offset in %qs", str,
+	       "-mstack-protector-guard-offset=");
+
+      riscv_stack_protector_guard_offset = offs;
+    }
+
 }
 
 /* Implement TARGET_CONDITIONAL_REGISTER_USAGE.  */

gcc/config/riscv/riscv.md

@@ -65,6 +65,10 @@
   UNSPECV_BLOCKAGE
   UNSPECV_FENCE
   UNSPECV_FENCE_I
+
+  ;; Stack Smash Protector
+  UNSPEC_SSP_SET
+  UNSPEC_SSP_TEST
 ])
 
 (define_constants
@@ -2523,6 +2527,82 @@
   ""
 {})
 
+;; Named patterns for stack smashing protection.
+
+(define_expand "stack_protect_set"
+  [(match_operand 0 "memory_operand")
+   (match_operand 1 "memory_operand")]
+  ""
+{
+  machine_mode mode = GET_MODE (operands[0]);
+  if (riscv_stack_protector_guard == SSP_TLS)
+  {
+    rtx reg = gen_rtx_REG (Pmode, riscv_stack_protector_guard_reg);
+    rtx offset = GEN_INT (riscv_stack_protector_guard_offset);
+    rtx addr = gen_rtx_PLUS (Pmode, reg, offset);
+    operands[1] = gen_rtx_MEM (Pmode, addr);
+  }
+
+  emit_insn ((mode == DImode
+	      ? gen_stack_protect_set_di
+	      : gen_stack_protect_set_si) (operands[0], operands[1]));
+  DONE;
+})
+
+;; DO NOT SPLIT THIS PATTERN.  It is important for security reasons that the
+;; canary value does not live beyond the life of this sequence.
+(define_insn "stack_protect_set_<mode>"
+  [(set (match_operand:GPR 0 "memory_operand" "=m")
+	(unspec:GPR [(match_operand:GPR 1 "memory_operand" "m")]
+	 UNSPEC_SSP_SET))
+   (set (match_scratch:GPR 2 "=&r") (const_int 0))]
+  ""
+  "<load>\\t%2, %1\;<store>\\t%2, %0\;li\t%2, 0"
+  [(set_attr "length" "12")])
+
+(define_expand "stack_protect_test"
+  [(match_operand 0 "memory_operand")
+   (match_operand 1 "memory_operand")
+   (match_operand 2)]
+  ""
+{
+  rtx result;
+  machine_mode mode = GET_MODE (operands[0]);
+
+  result = gen_reg_rtx(mode);
+  if (riscv_stack_protector_guard == SSP_TLS)
+  {
+      rtx reg = gen_rtx_REG (Pmode, riscv_stack_protector_guard_reg);
+      rtx offset = GEN_INT (riscv_stack_protector_guard_offset);
+      rtx addr = gen_rtx_PLUS (Pmode, reg, offset);
+      operands[1] = gen_rtx_MEM (Pmode, addr);
+  }
+  emit_insn ((mode == DImode
+		  ? gen_stack_protect_test_di
+		  : gen_stack_protect_test_si) (result,
+					        operands[0],
+					        operands[1]));
+
+  if (mode == DImode)
+    emit_jump_insn (gen_cbranchdi4 (gen_rtx_EQ (VOIDmode, result, const0_rtx),
+				    result, const0_rtx, operands[2]));
+  else
+    emit_jump_insn (gen_cbranchsi4 (gen_rtx_EQ (VOIDmode, result, const0_rtx),
+				    result, const0_rtx, operands[2]));
+
+  DONE;
+})
+
+(define_insn "stack_protect_test_<mode>"
+  [(set (match_operand:GPR 0 "register_operand" "=r")
+	(unspec:GPR [(match_operand:GPR 1 "memory_operand" "m")
+		     (match_operand:GPR 2 "memory_operand" "m")]
+	 UNSPEC_SSP_TEST))
+   (clobber (match_scratch:GPR 3 "=&r"))]
+  ""
+  "<load>\t%3, %1\;<load>\t%0, %2\;xor\t%0, %3, %0\;li\t%3, 0"
+  [(set_attr "length" "12")])
+
 (include "sync.md")
 (include "peephole.md")
 (include "pic.md")

gcc/config/riscv/riscv.opt

@@ -151,3 +151,31 @@ Enum(riscv_align_data) String(xlen) Value(riscv_align_data_type_xlen)
 
 EnumValue
 Enum(riscv_align_data) String(natural) Value(riscv_align_data_type_natural)
+
+mstack-protector-guard=
+Target RejectNegative Joined Enum(stack_protector_guard) Var(riscv_stack_protector_guard) Init(SSP_GLOBAL)
+Use given stack-protector guard.
+
+Enum
+Name(stack_protector_guard) Type(enum stack_protector_guard)
+Valid arguments to -mstack-protector-guard=:
+
+EnumValue
+Enum(stack_protector_guard) String(tls) Value(SSP_TLS)
+
+EnumValue
+Enum(stack_protector_guard) String(global) Value(SSP_GLOBAL)
+
+mstack-protector-guard-reg=
+Target RejectNegative Joined Var(riscv_stack_protector_guard_reg_str)
+Use the given base register for addressing the stack-protector guard.
+
+TargetVariable
+int riscv_stack_protector_guard_reg = 0
+
+mstack-protector-guard-offset=
+Target RejectNegative Joined Integer Var(riscv_stack_protector_guard_offset_str)
+Use the given offset for addressing the stack-protector guard.
+
+TargetVariable
+long riscv_stack_protector_guard_offset = 0

gcc/doc/invoke.texi

@@ -1140,7 +1140,9 @@ See RS/6000 and PowerPC Options.
 -mexplicit-relocs  -mno-explicit-relocs @gol
 -mrelax  -mno-relax @gol
 -mriscv-attribute  -mmo-riscv-attribute @gol
--malign-data=@var{type}}
+-malign-data=@var{type} @gol
++-mstack-protector-guard=@var{guard} -mstack-protector-guard-reg=@var{reg} @gol
++-mstack-protector-guard-offset=@var{offset}}
 
 @emph{RL78 Options}
 @gccoptlist{-msim  -mmul=none  -mmul=g13  -mmul=g14  -mallregs @gol
@@ -25795,6 +25797,24 @@ Control how GCC aligns variables and constants of array, structure, or union
 types.  Supported values for @var{type} are @samp{xlen} which uses x register
 width as the alignment value, and @samp{natural} which uses natural alignment.
 @samp{xlen} is the default.
+
+@item -mstack-protector-guard=@var{guard}
+@itemx -mstack-protector-guard-reg=@var{reg}
+@itemx -mstack-protector-guard-offset=@var{offset}
+@opindex mstack-protector-guard
+@opindex mstack-protector-guard-reg
+@opindex mstack-protector-guard-offset
+Generate stack protection code using canary at @var{guard}.  Supported
+locations are @samp{global} for a global canary or @samp{tls} for per-thread
+canary in the TLS block.
+
+With the latter choice the options
+@option{-mstack-protector-guard-reg=@var{reg}} and
+@option{-mstack-protector-guard-offset=@var{offset}} furthermore specify
+which register to use as base register for reading the canary,
+and from what offset from that base register. There is no default
+register or offset as this is entirely for use within the Linux
+kernel.
 @end table
 
 @node RL78 Options