x86/mm: Clean up register saving in the __enc_copy() assembly code (13038801) · Commits · 戴 / test

Clean up the use of PUSH and POP and when registers are saved in the __enc_copy() assembly function in order to improve the readability of the code. Move parameter register saving into general purpose registers earlier in the code and move all the pushes to the beginning of the function with corresponding pops at the end. We do this to prepare fixes. Tested-by:

Gabriel Craciunescu <nix.or.die@gmail.com> Signed-off-by:

Tom Lendacky <thomas.lendacky@amd.com> Reviewed-by:

Borislav Petkov <bp@suse.de> Cc: Borislav Petkov <bp@alien8.de> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20180110192556.6026.74187.stgit@tlendack-t1.amdoffice.net Signed-off-by:

Ingo Molnar <mingo@kernel.org>

arch/x86/mm/mem_encrypt_boot.S

+10 −10

Original line number	Diff line number	Diff line
		@@ -103,20 +103,19 @@ ENTRY(__enc_copy)
		orq $X86_CR4_PGE, %rdx
		mov %rdx, %cr4

		push %r15

		movq %rcx, %r9 /* Save kernel length */
		movq %rdi, %r10 /* Save encrypted kernel address */
		movq %rsi, %r11 /* Save decrypted kernel address */

		/* Set the PAT register PA5 entry to write-protect */
		push %rcx
		movl $MSR_IA32_CR_PAT, %ecx
		rdmsr
		push %rdx /* Save original PAT value */
		mov %rdx, %r15 /* Save original PAT value */
		andl $0xffff00ff, %edx /* Clear PA5 */
		orl $0x00000500, %edx /* Set PA5 to WP */
		wrmsr
		pop %rdx /* RDX contains original PAT value */
		pop %rcx

		movq %rcx, %r9 /* Save kernel length */
		movq %rdi, %r10 /* Save encrypted kernel address */
		movq %rsi, %r11 /* Save decrypted kernel address */

		wbinvd /* Invalidate any cache entries */

		@@ -138,12 +137,13 @@ ENTRY(__enc_copy)
		jnz 1b /* Kernel length not zero? */

		/* Restore PAT register */
		push %rdx /* Save original PAT value */
		movl $MSR_IA32_CR_PAT, %ecx
		rdmsr
		pop %rdx /* Restore original PAT value */
		mov %r15, %rdx /* Restore original PAT value */
		wrmsr

		pop %r15

		ret
		.L__enc_copy_end:
		ENDPROC(__enc_copy)

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