arm64: BTI: Decode BYTPE bits when printing PSTATE (ec94a46e) · Commits · 戴 / test

The current code to print PSTATE symbolically when generating backtraces etc., does not include the BYTPE field used by Branch Target Identification. So, decode BYTPE and print it too. In the interests of human-readability, print the classes of BTI matched. The symbolic notation, BYTPE (PSTATE[11:10]) and permitted classes of subsequent instruction are: -- (BTYPE=0b00): any insn jc (BTYPE=0b01): BTI jc, BTI j, BTI c, PACIxSP -c (BYTPE=0b10): BTI jc, BTI c, PACIxSP j- (BTYPE=0b11): BTI jc, BTI j Signed-off-by:

Mark Brown <broonie@kernel.org> Signed-off-by:

Dave Martin <Dave.Martin@arm.com> Reviewed-by:

Kees Cook <keescook@chromium.org> Signed-off-by:

Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/kernel/process.c

+15 −2

Original line number	Diff line number	Diff line
		@@ -211,6 +211,15 @@ void machine_restart(char *cmd)
		while (1);
		}

		#define bstr(suffix, str) [PSR_BTYPE_ ## suffix >> PSR_BTYPE_SHIFT] = str
		static const char *const btypes[] = {
		bstr(NONE, "--"),
		bstr( JC, "jc"),
		bstr( C, "-c"),
		bstr( J , "j-")
		};
		#undef bstr

		static void print_pstate(struct pt_regs *regs)
		{
		u64 pstate = regs->pstate;
		@@ -229,7 +238,10 @@ static void print_pstate(struct pt_regs *regs)
		pstate & PSR_AA32_I_BIT ? 'I' : 'i',
		pstate & PSR_AA32_F_BIT ? 'F' : 'f');
		} else {
		printk("pstate: %08llx (%c%c%c%c %c%c%c%c %cPAN %cUAO)\n",
		const char *btype_str = btypes[(pstate & PSR_BTYPE_MASK) >>
		PSR_BTYPE_SHIFT];

		printk("pstate: %08llx (%c%c%c%c %c%c%c%c %cPAN %cUAO BTYPE=%s)\n",
		pstate,
		pstate & PSR_N_BIT ? 'N' : 'n',
		pstate & PSR_Z_BIT ? 'Z' : 'z',
		@@ -240,7 +252,8 @@ static void print_pstate(struct pt_regs *regs)
		pstate & PSR_I_BIT ? 'I' : 'i',
		pstate & PSR_F_BIT ? 'F' : 'f',
		pstate & PSR_PAN_BIT ? '+' : '-',
		pstate & PSR_UAO_BIT ? '+' : '-');
		pstate & PSR_UAO_BIT ? '+' : '-',
		btype_str);
		}
		}

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