diff mbox series

[v4,01/12] riscv: ftrace: support fastcc in Clang for WITH_ARGS

Message ID 20250407180838.42877-1-andybnac@gmail.com (mailing list archive)
State New
Headers show
Series [v4,01/12] riscv: ftrace: support fastcc in Clang for WITH_ARGS | expand

Commit Message

Andy Chiu April 7, 2025, 6:08 p.m. UTC
From: Andy Chiu <andy.chiu@sifive.com>

Some caller-saved registers which are not defined as function arguments
in the ABI can still be passed as arguments when the kernel is compiled
with Clang. As a result, we must save and restore those registers to
prevent ftrace from clobbering them.

- [1]: https://reviews.llvm.org/D68559

Reported-by: Evgenii Shatokhin <e.shatokhin@yadro.com>
Closes: https://lore.kernel.org/linux-riscv/7e7c7914-445d-426d-89a0-59a9199c45b1@yadro.com/
Fixes: 7caa9765465f ("ftrace: riscv: move from REGS to ARGS")
Acked-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Björn Töpel <bjorn@rivosinc.com>
Signed-off-by: Andy Chiu <andy.chiu@sifive.com>

---
Changelogs v4:
 - Add a fix tag (Björn, Evgenii)
---
 arch/riscv/include/asm/ftrace.h |  7 +++++++
 arch/riscv/kernel/asm-offsets.c |  7 +++++++
 arch/riscv/kernel/mcount-dyn.S  | 16 ++++++++++++++--
 3 files changed, 28 insertions(+), 2 deletions(-)

Comments

Björn Töpel April 10, 2025, 8:05 p.m. UTC | #1
(Trimming the Cc:-list a bit)

Hi Andy!

Andy Chiu <andybnac@gmail.com> writes:

> From: Andy Chiu <andy.chiu@sifive.com>
...

(Oh, if you send another revision, please add a cover, so it's easier to
comment around the full series.)

Thanks a lot for doing the lion part of this series, Andy! With this in
place, *finally* stop machine way of text patching is past us, and we
can move RISC-V out from the 20th century. ;-)

I applied your series, and Steven's series [1] to [2], and ran that on
QEMU (riscv64, ~RVA23), and on Milk-V Jupiter (Spacemit K1) with:
 * CONFIG_FTRACE_STARTUP_TEST
 * ftrace kselftest

No visible regressions, and now the ftrace kselftest can actually
complete! For the series:

Tested-by: Björn Töpel <bjorn@rivosinc.com>

[1] https://lore.kernel.org/all/20250409151549.788068911@goodmis.org/
[2] commit 3b07108ada81 ("Merge tag 'linux_kselftest-fixes-6.15-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest")


Björn
diff mbox series

Patch

diff --git a/arch/riscv/include/asm/ftrace.h b/arch/riscv/include/asm/ftrace.h
index d627f63ee289..d8b2138bd9c6 100644
--- a/arch/riscv/include/asm/ftrace.h
+++ b/arch/riscv/include/asm/ftrace.h
@@ -146,6 +146,13 @@  struct __arch_ftrace_regs {
 			unsigned long a5;
 			unsigned long a6;
 			unsigned long a7;
+#ifdef CONFIG_CC_IS_CLANG
+			unsigned long t2;
+			unsigned long t3;
+			unsigned long t4;
+			unsigned long t5;
+			unsigned long t6;
+#endif
 		};
 	};
 };
diff --git a/arch/riscv/kernel/asm-offsets.c b/arch/riscv/kernel/asm-offsets.c
index 16490755304e..7c43c8e26ae7 100644
--- a/arch/riscv/kernel/asm-offsets.c
+++ b/arch/riscv/kernel/asm-offsets.c
@@ -501,6 +501,13 @@  void asm_offsets(void)
 	DEFINE(FREGS_SP,	    offsetof(struct __arch_ftrace_regs, sp));
 	DEFINE(FREGS_S0,	    offsetof(struct __arch_ftrace_regs, s0));
 	DEFINE(FREGS_T1,	    offsetof(struct __arch_ftrace_regs, t1));
+#ifdef CONFIG_CC_IS_CLANG
+	DEFINE(FREGS_T2,	    offsetof(struct __arch_ftrace_regs, t2));
+	DEFINE(FREGS_T3,	    offsetof(struct __arch_ftrace_regs, t3));
+	DEFINE(FREGS_T4,	    offsetof(struct __arch_ftrace_regs, t4));
+	DEFINE(FREGS_T5,	    offsetof(struct __arch_ftrace_regs, t5));
+	DEFINE(FREGS_T6,	    offsetof(struct __arch_ftrace_regs, t6));
+#endif
 	DEFINE(FREGS_A0,	    offsetof(struct __arch_ftrace_regs, a0));
 	DEFINE(FREGS_A1,	    offsetof(struct __arch_ftrace_regs, a1));
 	DEFINE(FREGS_A2,	    offsetof(struct __arch_ftrace_regs, a2));
diff --git a/arch/riscv/kernel/mcount-dyn.S b/arch/riscv/kernel/mcount-dyn.S
index 745dd4c4a69c..e988bd26b28b 100644
--- a/arch/riscv/kernel/mcount-dyn.S
+++ b/arch/riscv/kernel/mcount-dyn.S
@@ -96,7 +96,13 @@ 
 	REG_S	x8,  FREGS_S0(sp)
 #endif
 	REG_S	x6,  FREGS_T1(sp)
-
+#ifdef CONFIG_CC_IS_CLANG
+	REG_S	x7,  FREGS_T2(sp)
+	REG_S	x28, FREGS_T3(sp)
+	REG_S	x29, FREGS_T4(sp)
+	REG_S	x30, FREGS_T5(sp)
+	REG_S	x31, FREGS_T6(sp)
+#endif
 	// save the arguments
 	REG_S	x10, FREGS_A0(sp)
 	REG_S	x11, FREGS_A1(sp)
@@ -115,7 +121,13 @@ 
 	REG_L	x8, FREGS_S0(sp)
 #endif
 	REG_L	x6,  FREGS_T1(sp)
-
+#ifdef CONFIG_CC_IS_CLANG
+	REG_L	x7,  FREGS_T2(sp)
+	REG_L	x28, FREGS_T3(sp)
+	REG_L	x29, FREGS_T4(sp)
+	REG_L	x30, FREGS_T5(sp)
+	REG_L	x31, FREGS_T6(sp)
+#endif
 	// restore the arguments
 	REG_L	x10, FREGS_A0(sp)
 	REG_L	x11, FREGS_A1(sp)