arm64: fix el2_setup check of CurrentEL (974c8e45) · Commits · 戴 / test

The CurrentEL system register reports the Current Exception Level of the CPU. It doesn't say anything about the stack handling, and yet we compare it to PSR_MODE_EL2t and PSR_MODE_EL2h. It works by chance because PSR_MODE_EL2t happens to match the right bits, but that's otherwise a very bad idea. Just check for the EL value instead. Signed-off-by:

Marc Zyngier <marc.zyngier@arm.com> [catalin.marinas@arm.com: fixed arch/arm64/kernel/efi-entry.S] Signed-off-by:

Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/include/asm/ptrace.h

+4 −0

Original line number	Diff line number	Diff line
		@@ -21,6 +21,10 @@

		#include <uapi/asm/ptrace.h>

		/* Current Exception Level values, as contained in CurrentEL */
		#define CurrentEL_EL1 (1 << 2)
		#define CurrentEL_EL2 (2 << 2)

		/* AArch32-specific ptrace requests */
		#define COMPAT_PTRACE_GETREGS 12
		#define COMPAT_PTRACE_SETREGS 13

arch/arm64/kernel/efi-entry.S

+1 −2

Original line number	Diff line number	Diff line
		@@ -78,8 +78,7 @@ ENTRY(efi_stub_entry)

		/* Turn off Dcache and MMU */
		mrs x0, CurrentEL
		cmp x0, #PSR_MODE_EL2t
		ccmp x0, #PSR_MODE_EL2h, #0x4, ne
		cmp x0, #CurrentEL_EL2
		b.ne 1f
		mrs x0, sctlr_el2
		bic x0, x0, #1 << 0 // clear SCTLR.M

arch/arm64/kernel/head.S

+1 −2

Original line number	Diff line number	Diff line
		@@ -270,8 +270,7 @@ ENDPROC(stext)
		*/
		ENTRY(el2_setup)
		mrs x0, CurrentEL
		cmp x0, #PSR_MODE_EL2t
		ccmp x0, #PSR_MODE_EL2h, #0x4, ne
		cmp x0, #CurrentEL_EL2
		b.ne 1f
		mrs x0, sctlr_el2
		CPU_BE( orr x0, x0, #(1 << 25) ) // Set the EE bit for EL2

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