https://gcc.gnu.org/g:0cd1f03939d57a71bcfaad6ad051e16aadd4d58d
commit r16-5192-g0cd1f03939d57a71bcfaad6ad051e16aadd4d58d Author: Stefan Schulze Frielinghaus <[email protected]> Date: Wed Nov 12 11:24:38 2025 +0100 s390: Support global stack protector So far only a per thread canary in the TLS block is supported. This patch adds support for a global canary, too. For this the new option -mstack-protector-guard={global,tls} is added which defaults to tls. The global canary is expected at symbol __stack_chk_guard which means for a function prologue instructions larl/l(g)fr + mvc are emitted and for an epilogue larl/l(g)fr + clc. Furthermore, option -mstack-protector-guard-record is added which is inspired by -mrecord-mcount and generates section __stack_protector_loc containing pointers to all instructions which load the address of the global guard. Thus, this option has only an effect in conjunction with -mstack-protector-guard=global. The intended use is for the Linux kernel in order to support run-time patching. In each task_struct of the kernel a canary is held which will be copied into the lowcore. Since the kernel supports migration of the lowcore at boot time, addresses are not necessarily constant. Therefore, the kernel expects that all instructions loading the address of the canary to be of format RIL or more precisely are either larl or lgrl and that the instructions addresses are recorded in section __stack_protector_loc. The kernel is then required to patch those instructions e.g. to llilf during boot. In total this means -mstack-protector-guard=global emits code suitable for user and kernel space. gcc/ChangeLog: * config/s390/s390-opts.h (enum stack_protector_guard): Define SP_TLS and SP_GLOBAL. * config/s390/s390.h (TARGET_SP_GLOBAL_GUARD): Define predicate. (TARGET_SP_TLS_GUARD): Define predicate. * config/s390/s390.md (stack_protect_global_guard_addr<mode>): New insn. (stack_protect_set): Also deal with a global guard. (stack_protect_test): Also deal with a global guard. * config/s390/s390.opt (-mstack-protector-guard={global,tls}): New option. (-mstack-protector-guard-record) New option. gcc/testsuite/ChangeLog: * gcc.target/s390/stack-protector-guard-global-1.c: New test. * gcc.target/s390/stack-protector-guard-global-2.c: New test. * gcc.target/s390/stack-protector-guard-global-3.c: New test. * gcc.target/s390/stack-protector-guard-global-4.c: New test. Diff: --- gcc/config/s390/s390-opts.h | 8 ++ gcc/config/s390/s390.h | 3 + gcc/config/s390/s390.md | 87 ++++++++++++++++++---- gcc/config/s390/s390.opt | 18 +++++ .../s390/stack-protector-guard-global-1.c | 27 +++++++ .../s390/stack-protector-guard-global-2.c | 5 ++ .../s390/stack-protector-guard-global-3.c | 6 ++ .../s390/stack-protector-guard-global-4.c | 6 ++ 8 files changed, 144 insertions(+), 16 deletions(-) diff --git a/gcc/config/s390/s390-opts.h b/gcc/config/s390/s390-opts.h index 9cacb2c29d1c..29dd4a5f77f6 100644 --- a/gcc/config/s390/s390-opts.h +++ b/gcc/config/s390/s390-opts.h @@ -53,4 +53,12 @@ enum indirect_branch { indirect_branch_thunk_inline, indirect_branch_thunk_extern }; + + +/* Where to get the canary for the stack protector. */ +enum stack_protector_guard +{ + SP_TLS, /* per-thread canary in TLS block */ + SP_GLOBAL /* global canary */ +}; #endif diff --git a/gcc/config/s390/s390.h b/gcc/config/s390/s390.h index 6478be8c7acd..a5a3db0bb21d 100644 --- a/gcc/config/s390/s390.h +++ b/gcc/config/s390/s390.h @@ -251,6 +251,9 @@ enum processor_flags && (s390_tune < PROCESSOR_2964_Z13 || (VAL) != const0_rtx) \ && (!CONST_INT_P (LEN) || INTVAL ((LEN)) > TARGET_SETMEM_PREFETCH_DISTANCE)) +#define TARGET_SP_GLOBAL_GUARD (s390_stack_protector_guard == SP_GLOBAL) +#define TARGET_SP_TLS_GUARD (s390_stack_protector_guard == SP_TLS) + /* Run-time target specification. */ /* Defaults for option flags defined only on some subtargets. */ diff --git a/gcc/config/s390/s390.md b/gcc/config/s390/s390.md index 06876a5563a9..db02bd425d74 100644 --- a/gcc/config/s390/s390.md +++ b/gcc/config/s390/s390.md @@ -312,6 +312,7 @@ ; Stack Protector UNSPECV_SP_GET_TP + UNSPECV_SP_GLOBAL_GUARD_ADDR ]) ;; @@ -12059,6 +12060,36 @@ ; Stack Protector Patterns ; +(define_insn "stack_protect_global_guard_addr<mode>" + [(set (match_operand:P 0 "register_operand" "=d") + (unspec_volatile:P [(const_int 0)] UNSPECV_SP_GLOBAL_GUARD_ADDR))] + "" +{ + if (flag_s390_stack_protector_guard_record) + fprintf (asm_out_file, "1:\n"); + if (flag_pic) + { + if (TARGET_Z10) + output_asm_insn ("l<g>rl\t%0,__stack_chk_guard@GOTENT", operands); + else + { + output_asm_insn ("larl\t%0,__stack_chk_guard@GOTENT", operands); + output_asm_insn ("l<g>\t%0,0(%0)", operands); + } + } + else + output_asm_insn ("larl\t%0,__stack_chk_guard", operands); + if (flag_s390_stack_protector_guard_record) + fprintf (asm_out_file, "\t.section __stack_protector_loc,\\"a\\",@progbits\n" + "\t.%s 1b\n" + "\t.previous\n", TARGET_64BIT ? "quad" : "long"); + return ""; +} + [(set (attr "mnemonic") + (cond [(match_test "flag_pic && TARGET_Z10") (const_string "l<g>rl") + (match_test "flag_pic && !TARGET_Z10") (const_string "*")] + (const_string "larl")))]) + ; Insns stack_protect_get_tp{si,di} are similar to *get_tp_{31,64} but still ; distinct in the sense that they force recomputation of the thread pointer ; instead of potentially reloading it from stack. @@ -12087,16 +12118,28 @@ (match_operand 1 "memory_operand" ""))] "" { -#ifdef TARGET_THREAD_SSP_OFFSET - rtx tp = gen_reg_rtx (Pmode); - if (TARGET_64BIT) - emit_insn (gen_stack_protect_get_tpdi (tp)); + if (TARGET_SP_GLOBAL_GUARD) + { + rtx addr = gen_reg_rtx (Pmode); + if (TARGET_64BIT) + emit_insn (gen_stack_protect_global_guard_addrdi (addr)); + else + emit_insn (gen_stack_protect_global_guard_addrsi (addr)); + operands[1] = gen_rtx_MEM (Pmode, addr); + } else - emit_insn (gen_stack_protect_get_tpsi (tp)); - operands[1] - = gen_rtx_MEM (Pmode, gen_rtx_PLUS (Pmode, tp, - GEN_INT (TARGET_THREAD_SSP_OFFSET))); + { +#ifdef TARGET_THREAD_SSP_OFFSET + rtx tp = gen_reg_rtx (Pmode); + if (TARGET_64BIT) + emit_insn (gen_stack_protect_get_tpdi (tp)); + else + emit_insn (gen_stack_protect_get_tpsi (tp)); + operands[1] + = gen_rtx_MEM (Pmode, gen_rtx_PLUS (Pmode, tp, + GEN_INT (TARGET_THREAD_SSP_OFFSET))); #endif + } if (TARGET_64BIT) emit_insn (gen_stack_protect_setdi (operands[0], operands[1])); else @@ -12120,16 +12163,28 @@ "" { rtx cc_reg, test; -#ifdef TARGET_THREAD_SSP_OFFSET - rtx tp = gen_reg_rtx (Pmode); - if (TARGET_64BIT) - emit_insn (gen_stack_protect_get_tpdi (tp)); + if (TARGET_SP_GLOBAL_GUARD) + { + rtx addr = gen_reg_rtx (Pmode); + if (TARGET_64BIT) + emit_insn (gen_stack_protect_global_guard_addrdi (addr)); + else + emit_insn (gen_stack_protect_global_guard_addrsi (addr)); + operands[1] = gen_rtx_MEM (Pmode, addr); + } else - emit_insn (gen_stack_protect_get_tpsi (tp)); - operands[1] - = gen_rtx_MEM (Pmode, gen_rtx_PLUS (Pmode, tp, - GEN_INT (TARGET_THREAD_SSP_OFFSET))); + { +#ifdef TARGET_THREAD_SSP_OFFSET + rtx tp = gen_reg_rtx (Pmode); + if (TARGET_64BIT) + emit_insn (gen_stack_protect_get_tpdi (tp)); + else + emit_insn (gen_stack_protect_get_tpsi (tp)); + operands[1] + = gen_rtx_MEM (Pmode, gen_rtx_PLUS (Pmode, tp, + GEN_INT (TARGET_THREAD_SSP_OFFSET))); #endif + } if (TARGET_64BIT) emit_insn (gen_stack_protect_testdi (operands[0], operands[1])); else diff --git a/gcc/config/s390/s390.opt b/gcc/config/s390/s390.opt index 6753a9326be2..a82992ef7efb 100644 --- a/gcc/config/s390/s390.opt +++ b/gcc/config/s390/s390.opt @@ -196,6 +196,24 @@ mno-stack-guard Target RejectNegative Alias(mstack-guard=,0) Negative(mstack-guard=) Switches off the -mstack-guard= option. +mstack-protector-guard= +Target RejectNegative Joined Enum(stack_protector_guard) Var(s390_stack_protector_guard) Init(SP_TLS) +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(SP_TLS) + +EnumValue +Enum(stack_protector_guard) String(global) Value(SP_GLOBAL) + +mstack-protector-guard-record +Target Var(flag_s390_stack_protector_guard_record) +Generate section __stack_protector_loc containing pointers to all instructions which load the address of the global guard. + mstack-size= Target RejectNegative Joined UInteger Var(s390_stack_size) Save Emit extra code in the function prologue in order to trap if the stack size exceeds the given limit. diff --git a/gcc/testsuite/gcc.target/s390/stack-protector-guard-global-1.c b/gcc/testsuite/gcc.target/s390/stack-protector-guard-global-1.c new file mode 100644 index 000000000000..f276645adcb1 --- /dev/null +++ b/gcc/testsuite/gcc.target/s390/stack-protector-guard-global-1.c @@ -0,0 +1,27 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -fstack-protector-all -mstack-protector-guard=global -mstack-protector-guard-record" } */ +/* { dg-final { scan-assembler-times {\n1:\n\tlarl\t%r[0-9]+,__stack_chk_guard\n} 4 } } */ + +void test_0 (void) { } + +void test_1 (void) +{ + __asm__ __volatile ("" ::: + "r0", + "r1", + "r2", + "r3", + "r4", + "r5", + "r6", + "r7", + "r8", + "r9", + "r10", + "r11", +#ifndef __PIC__ + "r12", +#endif + "r13", + "r14"); +} diff --git a/gcc/testsuite/gcc.target/s390/stack-protector-guard-global-2.c b/gcc/testsuite/gcc.target/s390/stack-protector-guard-global-2.c new file mode 100644 index 000000000000..7441a87adf7a --- /dev/null +++ b/gcc/testsuite/gcc.target/s390/stack-protector-guard-global-2.c @@ -0,0 +1,5 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -fstack-protector-all -mstack-protector-guard=global -mstack-protector-guard-record -fPIC" } */ +/* { dg-final { scan-assembler-times {\n1:\n\t(larl|lg?rl)\t%r[0-9]+,__stack_chk_guard@GOTENT\n} 4 } } */ + +#include "stack-protector-guard-global-1.c" diff --git a/gcc/testsuite/gcc.target/s390/stack-protector-guard-global-3.c b/gcc/testsuite/gcc.target/s390/stack-protector-guard-global-3.c new file mode 100644 index 000000000000..4ef379aa8f7e --- /dev/null +++ b/gcc/testsuite/gcc.target/s390/stack-protector-guard-global-3.c @@ -0,0 +1,6 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -fstack-protector-all -mstack-protector-guard=global" } */ +/* { dg-final { scan-assembler-times {\tlarl\t%r[0-9]+,__stack_chk_guard\n} 4 } } */ +/* { dg-final { scan-assembler-not {\n1:\n} } } */ + +#include "stack-protector-guard-global-1.c" diff --git a/gcc/testsuite/gcc.target/s390/stack-protector-guard-global-4.c b/gcc/testsuite/gcc.target/s390/stack-protector-guard-global-4.c new file mode 100644 index 000000000000..d57fc79bd833 --- /dev/null +++ b/gcc/testsuite/gcc.target/s390/stack-protector-guard-global-4.c @@ -0,0 +1,6 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -fstack-protector-all -mstack-protector-guard=global -fPIC" } */ +/* { dg-final { scan-assembler-times {\t(larl|lg?rl)\t%r[0-9]+,__stack_chk_guard@GOTENT\n} 4 } } */ +/* { dg-final { scan-assembler-not {\n1:\n} } } */ + +#include "stack-protector-guard-global-1.c"
