Unverified Commit 0de65288 authored by Andrew Jones's avatar Andrew Jones Committed by Palmer Dabbelt
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RISC-V: selftests: cbo: Ensure asm operands match constraints 



The 'i' constraint expects a constant operand, which fn and its
constant derivative MK_CBO(fn) are, but passing fn through a function
as a parameter and using a local variable for MK_CBO(fn) allow the
compiler to lose sight of that when no optimization is done. Use
a macro instead of a function and skip the local variable to ensure
the compiler uses constants, matching the asm constraints.

Reported-by: default avatarYunhui Cui <cuiyunhui@bytedance.com>
Closes: https://lore.kernel.org/all/20240117082514.42967-1-cuiyunhui@bytedance.com


Fixes: a29e2a48 ("RISC-V: selftests: Add CBO tests")
Signed-off-by: default avatarAndrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20240117130933.57514-2-ajones@ventanamicro.com


Cc: stable@vger.kernel.org
Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
parent a894e8ed

tools/testing/selftests/riscv/hwprobe/cbo.c

+8 −10
Original line number Diff line number Diff line
@@ -36,16 +36,14 @@ static void sigill_handler(int sig, siginfo_t *info, void *context) 
	regs[0] += 4;

}



static void cbo_insn(char *base, int fn)

{

	uint32_t insn = MK_CBO(fn);



	asm volatile(

	"mv	a0, %0\n"

	"li	a1, %1\n"

	".4byte	%2\n"

	: : "r" (base), "i" (fn), "i" (insn) : "a0", "a1", "memory");

}

#define cbo_insn(base, fn)							\

({										\

	asm volatile(								\

	"mv	a0, %0\n"							\

	"li	a1, %1\n"							\

	".4byte	%2\n"								\

	: : "r" (base), "i" (fn), "i" (MK_CBO(fn)) : "a0", "a1", "memory");	\

})



static void cbo_inval(char *base) { cbo_insn(base, 0); }

static void cbo_clean(char *base) { cbo_insn(base, 1); }