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Date: Thu, 24 Feb 2022 16:24:56 +0100
From: Emil Renner Berthing <kernel@...il.dk>
To: linux-riscv@...ts.infradead.org
Cc: Emil Renner Berthing <kernel@...il.dk>,
Steven Rostedt <rostedt@...dmis.org>,
Ingo Molnar <mingo@...hat.com>,
Paul Walmsley <paul.walmsley@...ive.com>,
Palmer Dabbelt <palmer@...belt.com>,
Albert Ou <aou@...s.berkeley.edu>,
Peter Zijlstra <peterz@...radead.org>,
Josh Poimboeuf <jpoimboe@...hat.com>,
Jason Baron <jbaron@...mai.com>,
Ard Biesheuvel <ardb@...nel.org>,
Jisheng Zhang <jszhang@...nel.org>,
Alexandre Ghiti <alex@...ti.fr>, linux-kernel@...r.kernel.org
Subject: [PATCH v3 8/8] riscv: Use asm/insn.h for dynamic ftrace
This converts kernel/ftrace.c to use asm/insn.h to generate the
instructions for dynamic ftrace. This also converts the make_call macro
into a regular static function.
Signed-off-by: Emil Renner Berthing <kernel@...il.dk>
---
arch/riscv/kernel/ftrace.c | 69 ++++++++++++--------------------------
1 file changed, 22 insertions(+), 47 deletions(-)
diff --git a/arch/riscv/kernel/ftrace.c b/arch/riscv/kernel/ftrace.c
index 2cc15dc45ce0..7dd3aafa17aa 100644
--- a/arch/riscv/kernel/ftrace.c
+++ b/arch/riscv/kernel/ftrace.c
@@ -9,6 +9,7 @@
#include <linux/uaccess.h>
#include <linux/memory.h>
#include <asm/cacheflush.h>
+#include <asm/insn.h>
#include <asm/patch.h>
#ifdef CONFIG_DYNAMIC_FTRACE
@@ -21,31 +22,13 @@
* Dynamic ftrace generates probes to call sites, so we must deal with
* both auipc and jalr at the same time.
*/
+static void make_call(unsigned long caller, unsigned long callee, unsigned int call[2])
+{
+ u32 offset = callee - caller;
-#define JALR_SIGN_MASK (0x00000800)
-#define JALR_OFFSET_MASK (0x00000fff)
-#define AUIPC_OFFSET_MASK (0xfffff000)
-#define AUIPC_PAD (0x00001000)
-#define JALR_SHIFT 20
-#define JALR_BASIC (0x000080e7)
-#define AUIPC_BASIC (0x00000097)
-#define NOP4 (0x00000013)
-
-#define make_call(caller, callee, call) \
-do { \
- call[0] = to_auipc_insn((unsigned int)((unsigned long)callee - \
- (unsigned long)caller)); \
- call[1] = to_jalr_insn((unsigned int)((unsigned long)callee - \
- (unsigned long)caller)); \
-} while (0)
-
-#define to_jalr_insn(offset) \
- (((offset & JALR_OFFSET_MASK) << JALR_SHIFT) | JALR_BASIC)
-
-#define to_auipc_insn(offset) \
- ((offset & JALR_SIGN_MASK) ? \
- (((offset & AUIPC_OFFSET_MASK) + AUIPC_PAD) | AUIPC_BASIC) : \
- ((offset & AUIPC_OFFSET_MASK) | AUIPC_BASIC))
+ call[0] = RISCV_INSN_AUIPC | RISCV_INSN_RD_RA | riscv_insn_u_imm(offset + 0x800);
+ call[1] = RISCV_INSN_JALR | RISCV_INSN_RD_RA | RISCV_INSN_RS1_RA | riscv_insn_i_imm(offset);
+}
int ftrace_arch_code_modify_prepare(void) __acquires(&text_mutex)
{
@@ -63,7 +46,7 @@ static int ftrace_check_current_call(unsigned long hook_pos,
unsigned int *expected)
{
unsigned int replaced[2];
- unsigned int nops[2] = {NOP4, NOP4};
+ unsigned int nops[2] = { RISCV_INSN_NOP, RISCV_INSN_NOP };
/* we expect nops at the hook position */
if (!expected)
@@ -95,7 +78,7 @@ static int __ftrace_modify_call(unsigned long hook_pos, unsigned long target,
bool enable)
{
unsigned int call[2];
- unsigned int nops[2] = {NOP4, NOP4};
+ unsigned int nops[2] = { RISCV_INSN_NOP, RISCV_INSN_NOP };
make_call(hook_pos, target, call);
@@ -108,39 +91,31 @@ static int __ftrace_modify_call(unsigned long hook_pos, unsigned long target,
}
/*
- * Put 5 instructions with 16 bytes at the front of function within
+ * Put 4 instructions with 16 bytes at the front of function within
* patchable function entry nops' area.
*
* 0: REG_S ra, -SZREG(sp)
- * 1: auipc ra, 0x?
- * 2: jalr -?(ra)
+ * 1: auipc ra, ?
+ * 2: jalr ra, ra, ?
* 3: REG_L ra, -SZREG(sp)
- *
- * So the opcodes is:
- * 0: 0xfe113c23 (sd)/0xfe112e23 (sw)
- * 1: 0x???????? -> auipc
- * 2: 0x???????? -> jalr
- * 3: 0xff813083 (ld)/0xffc12083 (lw)
*/
-#if __riscv_xlen == 64
-#define INSN0 0xfe113c23
-#define INSN3 0xff813083
-#elif __riscv_xlen == 32
-#define INSN0 0xfe112e23
-#define INSN3 0xffc12083
-#endif
-
#define FUNC_ENTRY_SIZE 16
#define FUNC_ENTRY_JMP 4
int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
{
- unsigned int call[4] = {INSN0, 0, 0, INSN3};
+ unsigned int call[4] = {
+ RISCV_INSN_REG_S | RISCV_INSN_RS2_RA | RISCV_INSN_RS1_SP |
+ riscv_insn_s_imm(-RISCV_INSN_SZREG),
+ 0,
+ 0,
+ RISCV_INSN_REG_L | RISCV_INSN_RD_RA | RISCV_INSN_RS1_SP |
+ riscv_insn_i_imm(-RISCV_INSN_SZREG),
+ };
unsigned long target = addr;
unsigned long caller = rec->ip + FUNC_ENTRY_JMP;
- call[1] = to_auipc_insn((unsigned int)(target - caller));
- call[2] = to_jalr_insn((unsigned int)(target - caller));
+ make_call(caller, target, &call[1]);
if (patch_text_nosync((void *)rec->ip, call, FUNC_ENTRY_SIZE))
return -EPERM;
@@ -151,7 +126,7 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
unsigned long addr)
{
- unsigned int nops[4] = {NOP4, NOP4, NOP4, NOP4};
+ unsigned int nops[4] = { RISCV_INSN_NOP, RISCV_INSN_NOP, RISCV_INSN_NOP, RISCV_INSN_NOP };
if (patch_text_nosync((void *)rec->ip, nops, FUNC_ENTRY_SIZE))
return -EPERM;
--
2.35.1
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