diff mbox series

[v5,09/13] riscv: switch to relative alternative entries

Message ID 20230128172856.3814-10-jszhang@kernel.org (mailing list archive)
State Accepted
Commit 8d23e94a443388e81c42ea7e476a5d79c1c795c9
Delegated to: Palmer Dabbelt
Headers show
Series riscv: improve boot time isa extensions handling | expand

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Context Check Description
conchuod/cover_letter success Series has a cover letter
conchuod/tree_selection success Guessed tree name to be for-next
conchuod/fixes_present success Fixes tag not required for -next series
conchuod/maintainers_pattern success MAINTAINERS pattern errors before the patch: 13 and now 13
conchuod/verify_signedoff success Signed-off-by tag matches author and committer
conchuod/kdoc success Errors and warnings before: 0 this patch: 0
conchuod/module_param success Was 0 now: 0
conchuod/build_rv64_gcc_allmodconfig success Errors and warnings before: 2050 this patch: 2050
conchuod/alphanumeric_selects success Out of order selects before the patch: 57 and now 57
conchuod/build_rv32_defconfig success Build OK
conchuod/dtb_warn_rv64 success Errors and warnings before: 2 this patch: 2
conchuod/header_inline success No static functions without inline keyword in header files
conchuod/checkpatch warning CHECK: Macro argument 'f' may be better as '(f)' to avoid precedence issues WARNING: unnecessary whitespace before a quoted newline
conchuod/source_inline success Was 0 now: 0
conchuod/build_rv64_nommu_k210_defconfig success Build OK
conchuod/verify_fixes success No Fixes tag
conchuod/build_rv64_nommu_virt_defconfig success Build OK

Commit Message

Jisheng Zhang Jan. 28, 2023, 5:28 p.m. UTC 
Instead of using absolute addresses for both the old instrucions and
the alternative instructions, use offsets relative to the alt_entry
values. So this not only cuts the size of the alternative entry, but
also meets the prerequisite for patching alternatives in the vDSO,
since absolute alternative entries are subject to dynamic relocation,
which is incompatible with the vDSO building.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
---
 arch/riscv/errata/sifive/errata.c           |  3 ++-
 arch/riscv/errata/thead/errata.c            | 11 ++++++++---
 arch/riscv/include/asm/alternative-macros.h | 20 ++++++++++----------
 arch/riscv/include/asm/alternative.h        | 17 +++++++++++------
 arch/riscv/kernel/cpufeature.c              |  8 +++++---
 5 files changed, 36 insertions(+), 23 deletions(-)
diff mbox series

Patch

diff --git a/arch/riscv/errata/sifive/errata.c b/arch/riscv/errata/sifive/errata.c
index 1031038423e7..ef9a4eec0dba 100644
--- a/arch/riscv/errata/sifive/errata.c
+++ b/arch/riscv/errata/sifive/errata.c
@@ -107,7 +107,8 @@  void __init_or_module sifive_errata_patch_func(struct alt_entry *begin,
 
 		tmp = (1U << alt->errata_id);
 		if (cpu_req_errata & tmp) {
-			patch_text_nosync(alt->old_ptr, alt->alt_ptr, alt->alt_len);
+			patch_text_nosync(ALT_OLD_PTR(alt), ALT_ALT_PTR(alt),
+					  alt->alt_len);
 			cpu_apply_errata |= tmp;
 		}
 	}
diff --git a/arch/riscv/errata/thead/errata.c b/arch/riscv/errata/thead/errata.c
index fac5742d1c1e..c0bea5c94128 100644
--- a/arch/riscv/errata/thead/errata.c
+++ b/arch/riscv/errata/thead/errata.c
@@ -87,6 +87,7 @@  void __init_or_module thead_errata_patch_func(struct alt_entry *begin, struct al
 	struct alt_entry *alt;
 	u32 cpu_req_errata = thead_errata_probe(stage, archid, impid);
 	u32 tmp;
+	void *oldptr, *altptr;
 
 	for (alt = begin; alt < end; alt++) {
 		if (alt->vendor_id != THEAD_VENDOR_ID)
@@ -96,12 +97,16 @@  void __init_or_module thead_errata_patch_func(struct alt_entry *begin, struct al
 
 		tmp = (1U << alt->errata_id);
 		if (cpu_req_errata & tmp) {
+			oldptr = ALT_OLD_PTR(alt);
+			altptr = ALT_ALT_PTR(alt);
+
 			/* On vm-alternatives, the mmu isn't running yet */
 			if (stage == RISCV_ALTERNATIVES_EARLY_BOOT)
-				memcpy((void *)__pa_symbol(alt->old_ptr),
-				       (void *)__pa_symbol(alt->alt_ptr), alt->alt_len);
+				memcpy((void *)__pa_symbol(oldptr),
+				       (void *)__pa_symbol(altptr),
+				       alt->alt_len);
 			else
-				patch_text_nosync(alt->old_ptr, alt->alt_ptr, alt->alt_len);
+				patch_text_nosync(oldptr, altptr, alt->alt_len);
 		}
 	}
 
diff --git a/arch/riscv/include/asm/alternative-macros.h b/arch/riscv/include/asm/alternative-macros.h
index 7226e2462584..cc6a81c00f2f 100644
--- a/arch/riscv/include/asm/alternative-macros.h
+++ b/arch/riscv/include/asm/alternative-macros.h
@@ -7,11 +7,11 @@ 
 #ifdef __ASSEMBLY__
 
 .macro ALT_ENTRY oldptr newptr vendor_id errata_id new_len
-	RISCV_PTR \oldptr
-	RISCV_PTR \newptr
-	REG_ASM \vendor_id
-	REG_ASM \new_len
-	.word	\errata_id
+	.4byte \oldptr - .
+	.4byte \newptr - .
+	.2byte \vendor_id
+	.2byte \new_len
+	.4byte \errata_id
 .endm
 
 .macro ALT_NEW_CONTENT vendor_id, errata_id, enable = 1, new_c : vararg
@@ -59,11 +59,11 @@ 
 #include <linux/stringify.h>
 
 #define ALT_ENTRY(oldptr, newptr, vendor_id, errata_id, newlen)		\
-	RISCV_PTR " " oldptr "\n"					\
-	RISCV_PTR " " newptr "\n"					\
-	REG_ASM " " vendor_id "\n"					\
-	REG_ASM " " newlen "\n"						\
-	".word " errata_id "\n"
+	".4byte	((" oldptr ") - .) \n"					\
+	".4byte	((" newptr ") - .) \n"					\
+	".2byte	" vendor_id "\n"					\
+	".2byte " newlen "\n"						\
+	".4byte	" errata_id "\n"
 
 #define ALT_NEW_CONTENT(vendor_id, errata_id, enable, new_c)		\
 	".if " __stringify(enable) " == 1\n"				\
diff --git a/arch/riscv/include/asm/alternative.h b/arch/riscv/include/asm/alternative.h
index 1bd4027d34ca..b8648d4f2ac1 100644
--- a/arch/riscv/include/asm/alternative.h
+++ b/arch/riscv/include/asm/alternative.h
@@ -23,6 +23,11 @@ 
 #define RISCV_ALTERNATIVES_MODULE	1 /* alternatives applied during module-init */
 #define RISCV_ALTERNATIVES_EARLY_BOOT	2 /* alternatives applied before mmu start */
 
+/* add the relative offset to the address of the offset to get the absolute address */
+#define __ALT_PTR(a, f)			((void *)&(a)->f + (a)->f)
+#define ALT_OLD_PTR(a)			__ALT_PTR(a, old_offset)
+#define ALT_ALT_PTR(a)			__ALT_PTR(a, alt_offset)
+
 void __init apply_boot_alternatives(void);
 void __init apply_early_boot_alternatives(void);
 void apply_module_alternatives(void *start, size_t length);
@@ -31,12 +36,12 @@  void riscv_alternative_fix_offsets(void *alt_ptr, unsigned int len,
 				   int patch_offset);
 
 struct alt_entry {
-	void *old_ptr;		 /* address of original instruciton or data  */
-	void *alt_ptr;		 /* address of replacement instruction or data */
-	unsigned long vendor_id; /* cpu vendor id */
-	unsigned long alt_len;   /* The replacement size */
-	unsigned int errata_id;  /* The errata id */
-} __packed;
+	s32 old_offset;		/* offset relative to original instruction or data  */
+	s32 alt_offset;		/* offset relative to replacement instruction or data */
+	u16 vendor_id;		/* cpu vendor id */
+	u16 alt_len;		/* The replacement size */
+	u32 errata_id;		/* The errata id */
+};
 
 struct errata_checkfunc_id {
 	unsigned long vendor_id;
diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index 6193f401f0c5..18ea518f9e68 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -281,6 +281,7 @@  void __init_or_module riscv_cpufeature_patch_func(struct alt_entry *begin,
 						  unsigned int stage)
 {
 	struct alt_entry *alt;
+	void *oldptr, *altptr;
 
 	if (stage == RISCV_ALTERNATIVES_EARLY_BOOT)
 		return;
@@ -297,9 +298,10 @@  void __init_or_module riscv_cpufeature_patch_func(struct alt_entry *begin,
 		if (!__riscv_isa_extension_available(NULL, alt->errata_id))
 			continue;
 
-		patch_text_nosync(alt->old_ptr, alt->alt_ptr, alt->alt_len);
-		riscv_alternative_fix_offsets(alt->old_ptr, alt->alt_len,
-					      alt->old_ptr - alt->alt_ptr);
+		oldptr = ALT_OLD_PTR(alt);
+		altptr = ALT_ALT_PTR(alt);
+		patch_text_nosync(oldptr, altptr, alt->alt_len);
+		riscv_alternative_fix_offsets(oldptr, alt->alt_len, oldptr - altptr);
 	}
 }
 #endif