RISC-V updates for v6.19-rc3

- Add probing and userspace reporting support for the standard RISC-V
   ISA extensions Zilsd and Zclsd, which implement load/store dual
   instructions on RV32
 
 - Abstract the register saving code in setup_sigcontext() so it can be
   used for stateful RISC-V ISA extensions beyond the vector extension
 
 - Add the SBI extension ID and some initial data structure definitions
   for the RISC-V standard SBI debug trigger extension
 
 - Clean up some code slightly: change some page table functions to
   avoid atomic operations oinn !SMP and to avoid unnecessary casts to
   atomic_long_t; and use the existing RISCV_FULL_BARRIER macro in
   place of some open-coded "fence rw,rw" instructions
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Merge tag 'riscv-for-linus-6.19-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux

Pull RISC-V updates from Paul Walmsley:
 "Nothing exotic here; these are the cleanup and new ISA extension
  probing patches (not including CFI):

   - Add probing and userspace reporting support for the standard RISC-V
     ISA extensions Zilsd and Zclsd, which implement load/store dual
     instructions on RV32

   - Abstract the register saving code in setup_sigcontext() so it can
     be used for stateful RISC-V ISA extensions beyond the vector
     extension

   - Add the SBI extension ID and some initial data structure
     definitions for the RISC-V standard SBI debug trigger extension

   - Clean up some code slightly: change some page table functions to
     avoid atomic operations oinn !SMP and to avoid unnecessary casts to
     atomic_long_t; and use the existing RISCV_FULL_BARRIER macro in
     place of some open-coded 'fence rw,rw' instructions"

* tag 'riscv-for-linus-6.19-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux:
  riscv: Add SBI debug trigger extension and function ids
  riscv/atomic.h: use RISCV_FULL_BARRIER in _arch_atomic* function.
  riscv: hwprobe: export Zilsd and Zclsd ISA extensions
  riscv: add ISA extension parsing for Zilsd and Zclsd
  dt-bindings: riscv: add Zilsd and Zclsd extension descriptions
  riscv: mm: use xchg() on non-atomic_long_t variables, not atomic_long_xchg()
  riscv: mm: ptep_get_and_clear(): avoid atomic ops when !CONFIG_SMP
  riscv: mm: pmdp_huge_get_and_clear(): avoid atomic ops when !CONFIG_SMP
  riscv: signal: abstract header saving for setup_sigcontext

Documentation/arch/riscv/hwprobe.rst

@@ -281,6 +281,14 @@ The following keys are defined:
   * :c:macro:`RISCV_HWPROBE_EXT_ZICBOP`: The Zicbop extension is supported, as
        ratified in commit 3dd606f ("Create cmobase-v1.0.pdf") of riscv-CMOs.
 
+  * :c:macro:`RISCV_HWPROBE_EXT_ZILSD`: The Zilsd extension is supported as
+       defined in the RISC-V ISA manual starting from commit f88abf1 ("Integrating
+       load/store pair for RV32 with the main manual") of the riscv-isa-manual.
+
+  * :c:macro:`RISCV_HWPROBE_EXT_ZCLSD`: The Zclsd extension is supported as
+       defined in the RISC-V ISA manual starting from commit f88abf1 ("Integrating
+       load/store pair for RV32 with the main manual") of the riscv-isa-manual.
+
 * :c:macro:`RISCV_HWPROBE_KEY_CPUPERF_0`: Deprecated.  Returns similar values to
      :c:macro:`RISCV_HWPROBE_KEY_MISALIGNED_SCALAR_PERF`, but the key was
      mistakenly classified as a bitmask rather than a value.

Documentation/devicetree/bindings/riscv/extensions.yaml

@@ -377,6 +377,20 @@ properties:
             guarantee on LR/SC sequences, as ratified in commit b1d806605f87
             ("Updated to ratified state.") of the riscv profiles specification.
 
+        - const: zilsd
+          description:
+            The standard Zilsd extension which provides support for aligned
+            register-pair load and store operations in 32-bit instruction
+            encodings, as ratified in commit f88abf1 ("Integrating
+            load/store pair for RV32 with the main manual") of riscv-isa-manual.
+
+        - const: zclsd
+          description:
+            The Zclsd extension implements the compressed (16-bit) version of the
+            Load/Store Pair for RV32. As with Zilsd, this extension was ratified
+            in commit f88abf1 ("Integrating load/store pair for RV32 with the
+            main manual") of riscv-isa-manual.
+
         - const: zk
           description:
             The standard Zk Standard Scalar cryptography extension as ratified
@@ -882,6 +896,16 @@ properties:
             anyOf:
               - const: v
               - const: zve32x
+      # Zclsd depends on Zilsd and Zca
+      - if:
+          contains:
+            anyOf:
+              - const: zclsd
+        then:
+          contains:
+            allOf:
+              - const: zilsd
+              - const: zca
 
 allOf:
   # Zcf extension does not exist on rv64
@@ -899,6 +923,18 @@ allOf:
           not:
             contains:
               const: zcf
+  # Zilsd extension does not exist on rv64
+  - if:
+      properties:
+        riscv,isa-base:
+          contains:
+            const: rv64i
+    then:
+      properties:
+        riscv,isa-extensions:
+          not:
+            contains:
+              const: zilsd
 
 additionalProperties: true
 ...

arch/riscv/include/asm/atomic.h

@@ -203,7 +203,7 @@ ATOMIC_OPS(xor, xor, i)
 		"	add            %[rc], %[p], %[a]\n"		\
 		"	sc." sfx ".rl  %[rc], %[rc], %[c]\n"		\
 		"	bnez           %[rc], 0b\n"			\
-		"	fence          rw, rw\n"			\
+		RISCV_FULL_BARRIER					\
 		"1:\n"							\
 		: [p]"=&r" (_prev), [rc]"=&r" (_rc), [c]"+A" (counter)	\
 		: [a]"r" (_a), [u]"r" (_u)				\
@@ -242,7 +242,7 @@ static __always_inline s64 arch_atomic64_fetch_add_unless(atomic64_t *v, s64 a,
 		"	addi            %[rc], %[p], 1\n"		\
 		"	sc." sfx ".rl   %[rc], %[rc], %[c]\n"		\
 		"	bnez            %[rc], 0b\n"			\
-		"	fence           rw, rw\n"			\
+		RISCV_FULL_BARRIER					\
 		"1:\n"							\
 		: [p]"=&r" (_prev), [rc]"=&r" (_rc), [c]"+A" (counter)	\
 		:							\
@@ -268,7 +268,7 @@ static __always_inline bool arch_atomic_inc_unless_negative(atomic_t *v)
 		"	addi            %[rc], %[p], -1\n"		\
 		"	sc." sfx ".rl   %[rc], %[rc], %[c]\n"		\
 		"	bnez            %[rc], 0b\n"			\
-		"	fence           rw, rw\n"			\
+		RISCV_FULL_BARRIER					\
 		"1:\n"							\
 		: [p]"=&r" (_prev), [rc]"=&r" (_rc), [c]"+A" (counter)	\
 		:							\
@@ -294,7 +294,7 @@ static __always_inline bool arch_atomic_dec_unless_positive(atomic_t *v)
 		"	bltz           %[rc], 1f\n"			\
 		"	sc." sfx ".rl  %[rc], %[rc], %[c]\n"		\
 		"	bnez           %[rc], 0b\n"			\
-		"	fence          rw, rw\n"			\
+		RISCV_FULL_BARRIER					\
 		"1:\n"							\
 		: [p]"=&r" (_prev), [rc]"=&r" (_rc), [c]"+A" (counter)	\
 		:							\

arch/riscv/include/asm/hwcap.h

@@ -108,6 +108,8 @@
 #define RISCV_ISA_EXT_ZICBOP		99
 #define RISCV_ISA_EXT_SVRSW60T59B	100
 #define RISCV_ISA_EXT_ZALASR		101
+#define RISCV_ISA_EXT_ZILSD		102
+#define RISCV_ISA_EXT_ZCLSD		103
 
 #define RISCV_ISA_EXT_XLINUXENVCFG	127
 

arch/riscv/include/asm/pgtable.h

@@ -660,7 +660,13 @@ extern int ptep_test_and_clear_young(struct vm_area_struct *vma, unsigned long a
 static inline pte_t ptep_get_and_clear(struct mm_struct *mm,
 				       unsigned long address, pte_t *ptep)
 {
-	pte_t pte = __pte(atomic_long_xchg((atomic_long_t *)ptep, 0));
+#ifdef CONFIG_SMP
+	pte_t pte = __pte(xchg(&ptep->pte, 0));
+#else
+	pte_t pte = *ptep;
+
+	set_pte(ptep, __pte(0));
+#endif
 
 	page_table_check_pte_clear(mm, pte);
 
@@ -997,7 +1003,13 @@ static inline int pmdp_test_and_clear_young(struct vm_area_struct *vma,
 static inline pmd_t pmdp_huge_get_and_clear(struct mm_struct *mm,
 					unsigned long address, pmd_t *pmdp)
 {
-	pmd_t pmd = __pmd(atomic_long_xchg((atomic_long_t *)pmdp, 0));
+#ifdef CONFIG_SMP
+	pmd_t pmd = __pmd(xchg(&pmdp->pmd, 0));
+#else
+	pmd_t pmd = *pmdp;
+
+	pmd_clear(pmdp);
+#endif
 
 	page_table_check_pmd_clear(mm, pmd);
 

arch/riscv/include/asm/sbi.h

@@ -37,6 +37,7 @@ enum sbi_ext_id {
 	SBI_EXT_NACL = 0x4E41434C,
 	SBI_EXT_FWFT = 0x46574654,
 	SBI_EXT_MPXY = 0x4D505859,
+	SBI_EXT_DBTR = 0x44425452,
 
 	/* Experimentals extensions must lie within this range */
 	SBI_EXT_EXPERIMENTAL_START = 0x08000000,
@@ -505,6 +506,34 @@ enum sbi_mpxy_rpmi_attribute_id {
 #define SBI_MPXY_CHAN_CAP_SEND_WITHOUT_RESP	BIT(4)
 #define SBI_MPXY_CHAN_CAP_GET_NOTIFICATIONS	BIT(5)
 
+/* SBI debug triggers function IDs */
+enum sbi_ext_dbtr_fid {
+	SBI_EXT_DBTR_NUM_TRIGGERS = 0,
+	SBI_EXT_DBTR_SETUP_SHMEM,
+	SBI_EXT_DBTR_TRIG_READ,
+	SBI_EXT_DBTR_TRIG_INSTALL,
+	SBI_EXT_DBTR_TRIG_UPDATE,
+	SBI_EXT_DBTR_TRIG_UNINSTALL,
+	SBI_EXT_DBTR_TRIG_ENABLE,
+	SBI_EXT_DBTR_TRIG_DISABLE,
+};
+
+struct sbi_dbtr_data_msg {
+	unsigned long tstate;
+	unsigned long tdata1;
+	unsigned long tdata2;
+	unsigned long tdata3;
+};
+
+struct sbi_dbtr_id_msg {
+	unsigned long idx;
+};
+
+union sbi_dbtr_shmem_entry {
+	struct sbi_dbtr_data_msg data;
+	struct sbi_dbtr_id_msg id;
+};
+
 /* SBI spec version fields */
 #define SBI_SPEC_VERSION_DEFAULT	0x1
 #define SBI_SPEC_VERSION_MAJOR_SHIFT	24

arch/riscv/include/asm/vector.h

@@ -424,6 +424,9 @@ static inline bool riscv_v_vstate_ctrl_user_allowed(void) { return false; }
 #define riscv_v_thread_free(tsk)		do {} while (0)
 #define  riscv_v_setup_ctx_cache()		do {} while (0)
 #define riscv_v_thread_alloc(tsk)		do {} while (0)
+#define get_cpu_vector_context()		do {} while (0)
+#define put_cpu_vector_context()		do {} while (0)
+#define riscv_v_vstate_set_restore(task, regs)	do {} while (0)
 
 #endif /* CONFIG_RISCV_ISA_V */
 

arch/riscv/include/uapi/asm/hwprobe.h

@@ -84,6 +84,9 @@ struct riscv_hwprobe {
 #define		RISCV_HWPROBE_EXT_ZABHA		(1ULL << 58)
 #define		RISCV_HWPROBE_EXT_ZALASR	(1ULL << 59)
 #define		RISCV_HWPROBE_EXT_ZICBOP	(1ULL << 60)
+#define		RISCV_HWPROBE_EXT_ZILSD		(1ULL << 61)
+#define		RISCV_HWPROBE_EXT_ZCLSD		(1ULL << 62)
+
 #define RISCV_HWPROBE_KEY_CPUPERF_0	5
 #define		RISCV_HWPROBE_MISALIGNED_UNKNOWN	(0 << 0)
 #define		RISCV_HWPROBE_MISALIGNED_EMULATED	(1 << 0)

arch/riscv/kernel/cpufeature.c

@@ -242,6 +242,28 @@ static int riscv_ext_zcf_validate(const struct riscv_isa_ext_data *data,
 	return -EPROBE_DEFER;
 }
 
+static int riscv_ext_zilsd_validate(const struct riscv_isa_ext_data *data,
+				    const unsigned long *isa_bitmap)
+{
+	if (IS_ENABLED(CONFIG_64BIT))
+		return -EINVAL;
+
+	return 0;
+}
+
+static int riscv_ext_zclsd_validate(const struct riscv_isa_ext_data *data,
+				    const unsigned long *isa_bitmap)
+{
+	if (IS_ENABLED(CONFIG_64BIT))
+		return -EINVAL;
+
+	if (__riscv_isa_extension_available(isa_bitmap, RISCV_ISA_EXT_ZILSD) &&
+	    __riscv_isa_extension_available(isa_bitmap, RISCV_ISA_EXT_ZCA))
+		return 0;
+
+	return -EPROBE_DEFER;
+}
+
 static int riscv_vector_f_validate(const struct riscv_isa_ext_data *data,
 				   const unsigned long *isa_bitmap)
 {
@@ -484,6 +506,8 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = {
 	__RISCV_ISA_EXT_DATA_VALIDATE(zcd, RISCV_ISA_EXT_ZCD, riscv_ext_zcd_validate),
 	__RISCV_ISA_EXT_DATA_VALIDATE(zcf, RISCV_ISA_EXT_ZCF, riscv_ext_zcf_validate),
 	__RISCV_ISA_EXT_DATA_VALIDATE(zcmop, RISCV_ISA_EXT_ZCMOP, riscv_ext_zca_depends),
+	__RISCV_ISA_EXT_DATA_VALIDATE(zclsd, RISCV_ISA_EXT_ZCLSD, riscv_ext_zclsd_validate),
+	__RISCV_ISA_EXT_DATA_VALIDATE(zilsd, RISCV_ISA_EXT_ZILSD, riscv_ext_zilsd_validate),
 	__RISCV_ISA_EXT_DATA(zba, RISCV_ISA_EXT_ZBA),
 	__RISCV_ISA_EXT_DATA(zbb, RISCV_ISA_EXT_ZBB),
 	__RISCV_ISA_EXT_DATA(zbc, RISCV_ISA_EXT_ZBC),

arch/riscv/kernel/signal.c

@@ -68,18 +68,19 @@ static long save_fp_state(struct pt_regs *regs,
 #define restore_fp_state(task, regs) (0)
 #endif
 
-#ifdef CONFIG_RISCV_ISA_V
-
-static long save_v_state(struct pt_regs *regs, void __user **sc_vec)
+static long save_v_state(struct pt_regs *regs, void __user *sc_vec)
 {
-	struct __riscv_ctx_hdr __user *hdr;
 	struct __sc_riscv_v_state __user *state;
 	void __user *datap;
 	long err;
 
-	hdr = *sc_vec;
-	/* Place state to the user's signal context space after the hdr */
-	state = (struct __sc_riscv_v_state __user *)(hdr + 1);
+	if (!IS_ENABLED(CONFIG_RISCV_ISA_V) ||
+	    !((has_vector() || has_xtheadvector()) &&
+	    riscv_v_vstate_query(regs)))
+		return 0;
+
+	/* Place state to the user's signal context space */
+	state = (struct __sc_riscv_v_state __user *)sc_vec;
 	/* Point datap right after the end of __sc_riscv_v_state */
 	datap = state + 1;
 
@@ -97,15 +98,11 @@ static long save_v_state(struct pt_regs *regs, void __user **sc_vec)
 	err |= __put_user((__force void *)datap, &state->v_state.datap);
 	/* Copy the whole vector content to user space datap. */
 	err |= __copy_to_user(datap, current->thread.vstate.datap, riscv_v_vsize);
-	/* Copy magic to the user space after saving  all vector conetext */
-	err |= __put_user(RISCV_V_MAGIC, &hdr->magic);
-	err |= __put_user(riscv_v_sc_size, &hdr->size);
 	if (unlikely(err))
-		return err;
+		return -EFAULT;
 
-	/* Only progress the sv_vec if everything has done successfully  */
-	*sc_vec += riscv_v_sc_size;
-	return 0;
+	/* Only return the size if everything has done successfully  */
+	return riscv_v_sc_size;
 }
 
 /*
@@ -142,10 +139,20 @@ static long __restore_v_state(struct pt_regs *regs, void __user *sc_vec)
 	 */
 	return copy_from_user(current->thread.vstate.datap, datap, riscv_v_vsize);
 }
-#else
-#define save_v_state(task, regs) (0)
-#define __restore_v_state(task, regs) (0)
-#endif
+
+struct arch_ext_priv {
+	__u32 magic;
+	long (*save)(struct pt_regs *regs, void __user *sc_vec);
+};
+
+struct arch_ext_priv arch_ext_list[] = {
+	{
+		.magic = RISCV_V_MAGIC,
+		.save = &save_v_state,
+	},
+};
+
+const size_t nr_arch_exts = ARRAY_SIZE(arch_ext_list);
 
 static long restore_sigcontext(struct pt_regs *regs,
 	struct sigcontext __user *sc)
@@ -270,7 +277,8 @@ static long setup_sigcontext(struct rt_sigframe __user *frame,
 {
 	struct sigcontext __user *sc = &frame->uc.uc_mcontext;
 	struct __riscv_ctx_hdr __user *sc_ext_ptr = &sc->sc_extdesc.hdr;
-	long err;
+	struct arch_ext_priv *arch_ext;
+	long err, i, ext_size;
 
 	/* sc_regs is structured the same as the start of pt_regs */
 	err = __copy_to_user(&sc->sc_regs, regs, sizeof(sc->sc_regs));
@@ -278,8 +286,20 @@ static long setup_sigcontext(struct rt_sigframe __user *frame,
 	if (has_fpu())
 		err |= save_fp_state(regs, &sc->sc_fpregs);
 	/* Save the vector state. */
-	if ((has_vector() || has_xtheadvector()) && riscv_v_vstate_query(regs))
-		err |= save_v_state(regs, (void __user **)&sc_ext_ptr);
+	for (i = 0; i < nr_arch_exts; i++) {
+		arch_ext = &arch_ext_list[i];
+		if (!arch_ext->save)
+			continue;
+
+		ext_size = arch_ext->save(regs, sc_ext_ptr + 1);
+		if (ext_size <= 0) {
+			err |= ext_size;
+		} else {
+			err |= __put_user(arch_ext->magic, &sc_ext_ptr->magic);
+			err |= __put_user(ext_size, &sc_ext_ptr->size);
+			sc_ext_ptr = (void *)sc_ext_ptr + ext_size;
+		}
+	}
 	/* Write zero to fp-reserved space and check it on restore_sigcontext */
 	err |= __put_user(0, &sc->sc_extdesc.reserved);
 	/* And put END __riscv_ctx_hdr at the end. */

arch/riscv/kernel/sys_hwprobe.c

@@ -121,6 +121,7 @@ static void hwprobe_isa_ext0(struct riscv_hwprobe *pair,
 		EXT_KEY(ZBS);
 		EXT_KEY(ZCA);
 		EXT_KEY(ZCB);
+		EXT_KEY(ZCLSD);
 		EXT_KEY(ZCMOP);
 		EXT_KEY(ZICBOM);
 		EXT_KEY(ZICBOP);
@@ -130,6 +131,7 @@ static void hwprobe_isa_ext0(struct riscv_hwprobe *pair,
 		EXT_KEY(ZIHINTNTL);
 		EXT_KEY(ZIHINTPAUSE);
 		EXT_KEY(ZIHPM);
+		EXT_KEY(ZILSD);
 		EXT_KEY(ZIMOP);
 		EXT_KEY(ZKND);
 		EXT_KEY(ZKNE);