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Commit 1855c543 authored by Michael Ellerman's avatar Michael Ellerman Committed by Greg Kroah-Hartman
Browse files

powerpc/powernv/idle: Restore AMR/UAMOR/AMOR after idle 



commit 53a712bae5dd919521a58d7bad773b949358add0 upstream.

In order to implement KUAP (Kernel Userspace Access Protection) on
Power9 we will be using the AMR, and therefore indirectly the
UAMOR/AMOR.

So save/restore these regs in the idle code.

Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
[ajd: Backport to 4.19 tree, CVE-2020-11669]
Signed-off-by: default avatarAndrew Donnellan <ajd@linux.ibm.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 5f547e7c

arch/powerpc/kernel/idle_book3s.S

+23 −4
Original line number Original line Diff line number Diff line
@@ -170,8 +170,11 @@ core_idle_lock_held: 
	bne-	core_idle_lock_held

	bne-	core_idle_lock_held

	blr

	blr





/* Reuse an unused pt_regs slot for IAMR */

/* Reuse some unused pt_regs slots for AMR/IAMR/UAMOR/UAMOR */

#define PNV_POWERSAVE_AMR	_TRAP

#define PNV_POWERSAVE_IAMR	_DAR

#define PNV_POWERSAVE_IAMR	_DAR

#define PNV_POWERSAVE_UAMOR	_DSISR

#define PNV_POWERSAVE_AMOR	RESULT





/*

/*

 * Pass requested state in r3:

 * Pass requested state in r3:
@@ -205,8 +208,16 @@ pnv_powersave_common: 
	SAVE_NVGPRS(r1)

	SAVE_NVGPRS(r1)





BEGIN_FTR_SECTION

BEGIN_FTR_SECTION

	mfspr	r4, SPRN_AMR

	mfspr	r5, SPRN_IAMR

	mfspr	r5, SPRN_IAMR

	mfspr	r6, SPRN_UAMOR

	std	r4, PNV_POWERSAVE_AMR(r1)

	std	r5, PNV_POWERSAVE_IAMR(r1)

	std	r5, PNV_POWERSAVE_IAMR(r1)

	std	r6, PNV_POWERSAVE_UAMOR(r1)

BEGIN_FTR_SECTION_NESTED(42)

	mfspr	r7, SPRN_AMOR

	std	r7, PNV_POWERSAVE_AMOR(r1)

END_FTR_SECTION_NESTED_IFSET(CPU_FTR_HVMODE, 42)

END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)

END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)





	mfcr	r5

	mfcr	r5
@@ -935,12 +946,20 @@ END_FTR_SECTION_IFSET(CPU_FTR_HVMODE) 
	REST_GPR(2, r1)

	REST_GPR(2, r1)





BEGIN_FTR_SECTION

BEGIN_FTR_SECTION

	/* IAMR was saved in pnv_powersave_common() */

	/* These regs were saved in pnv_powersave_common() */

	ld	r4, PNV_POWERSAVE_AMR(r1)

	ld	r5, PNV_POWERSAVE_IAMR(r1)

	ld	r5, PNV_POWERSAVE_IAMR(r1)

	ld	r6, PNV_POWERSAVE_UAMOR(r1)

	mtspr	SPRN_AMR, r4

	mtspr	SPRN_IAMR, r5

	mtspr	SPRN_IAMR, r5

	/*

	mtspr	SPRN_UAMOR, r6

	 * We don't need an isync here because the upcoming mtmsrd is

BEGIN_FTR_SECTION_NESTED(42)

	 * execution synchronizing.

	ld	r7, PNV_POWERSAVE_AMOR(r1)

	mtspr	SPRN_AMOR, r7

END_FTR_SECTION_NESTED_IFSET(CPU_FTR_HVMODE, 42)

	/*

	 * We don't need an isync here after restoring IAMR because the upcoming

	 * mtmsrd is execution synchronizing.

	 */

	 */

END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)

END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)