Unverified Commit f8693f6d authored by Andy Chiu's avatar Andy Chiu Committed by Palmer Dabbelt
Browse files

riscv: ftrace: support fastcc in Clang for WITH_ARGS 

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: default avatarEvgenii Shatokhin <e.shatokhin@yadro.com>
Closes: https://lore.kernel.org/linux-riscv/7e7c7914-445d-426d-89a0-59a9199c45b1@yadro.com/


Fixes: 7caa9765 ("ftrace: riscv: move from REGS to ARGS")
Acked-by: default avatarNathan Chancellor <nathan@kernel.org>
Reviewed-by: default avatarBjörn Töpel <bjorn@rivosinc.com>
Signed-off-by: default avatarAndy Chiu <andy.chiu@sifive.com>
Tested-by: default avatarBjörn Töpel <bjorn@rivosinc.com>
Link: https://lore.kernel.org/r/20250407180838.42877-1-andybnac@gmail.com


Signed-off-by: default avatarAlexandre Ghiti <alexghiti@rivosinc.com>
Signed-off-by: default avatarPalmer Dabbelt <palmer@dabbelt.com>
parent 9c32cda4

arch/riscv/include/asm/ftrace.h

+7 −0
Original line number Diff line number Diff line
@@ -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

		};

	};

};

arch/riscv/kernel/asm-offsets.c

+7 −0
Original line number Diff line number Diff line
@@ -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));

arch/riscv/kernel/mcount-dyn.S

+14 −2
Original line number Diff line number Diff line
@@ -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)