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From: Rohan McLure <rmclure@linux.ibm.com>
To: linuxppc-dev@lists.ozlabs.org
Cc: Rohan McLure <rmclure@linux.ibm.com>
Subject: [PATCH v6 25/25] powerpc/64e: Clear gprs on interrupt routine entry on Book3E
Date: Wed, 21 Sep 2022 16:56:05 +1000	[thread overview]
Message-ID: <20220921065605.1051927-26-rmclure@linux.ibm.com> (raw)
In-Reply-To: <20220921065605.1051927-1-rmclure@linux.ibm.com>

Zero GPRS r14-r31 on entry into the kernel for interrupt sources to
limit influence of user-space values in potential speculation gadgets.
Prior to this commit, all other GPRS are reassigned during the common
prologue to interrupt handlers and so need not be zeroised explicitly.

This may be done safely, without loss of register state prior to the
interrupt, as the common prologue saves the initial values of
non-volatiles, which are unconditionally restored in interrupt_64.S.
Mitigation defaults to enabled by INTERRUPT_SANITIZE_REGISTERS.

Signed-off-by: Rohan McLure <rmclure@linux.ibm.com>
---
V4: New patch.
V5: Depend on Kconfig option. Remove ZEROIZE_NVGPRS on bad kernel
stack handler.
V6: Change name of zeroize macro to be consistent with Book3S.
---
 arch/powerpc/kernel/exceptions-64e.S | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/exceptions-64e.S b/arch/powerpc/kernel/exceptions-64e.S
index f1d714acc945..d55c0a368dcb 100644
--- a/arch/powerpc/kernel/exceptions-64e.S
+++ b/arch/powerpc/kernel/exceptions-64e.S
@@ -366,6 +366,11 @@ ret_from_mc_except:
 	std	r14,PACA_EXMC+EX_R14(r13);				    \
 	std	r15,PACA_EXMC+EX_R15(r13)
 
+#ifdef CONFIG_INTERRUPT_SANITIZE_REGISTERS
+#define SANITIZE_ZEROIZE_NVGPRS()	ZEROIZE_NVGPRS()
+#else
+#define SANITIZE_ZEROIZE_NVGPRS()
+#endif
 
 /* Core exception code for all exceptions except TLB misses. */
 #define EXCEPTION_COMMON_LVL(n, scratch, excf)				    \
@@ -402,7 +407,8 @@ exc_##n##_common:							    \
 	std	r12,STACK_FRAME_OVERHEAD-16(r1); /* mark the frame */	    \
 	std	r3,_TRAP(r1);		/* set trap number		*/  \
 	std	r0,RESULT(r1);		/* clear regs->result */	    \
-	SAVE_NVGPRS(r1);
+	SAVE_NVGPRS(r1);						    \
+	SANITIZE_ZEROIZE_NVGPRS();	/* minimise speculation influence */
 
 #define EXCEPTION_COMMON(n) \
 	EXCEPTION_COMMON_LVL(n, SPRN_SPRG_GEN_SCRATCH, PACA_EXGEN)
-- 
2.34.1


  parent reply	other threads:[~2022-09-21  7:14 UTC|newest]

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-09-21  6:55 [PATCH v6 00/25] powerpc: Syscall wrapper and register clearing Rohan McLure
2022-09-21  6:55 ` [PATCH v6 01/25] powerpc: Remove asmlinkage from syscall handler definitions Rohan McLure
2022-09-21  6:55 ` [PATCH v6 02/25] powerpc: Save caller r3 prior to system_call_exception Rohan McLure
2022-09-21  6:55 ` [PATCH v6 03/25] powerpc: Add ZEROIZE_GPRS macros for register clears Rohan McLure
2022-09-21  6:55 ` [PATCH v6 04/25] powerpc/64s: Use {ZEROIZE,SAVE,REST}_GPRS macros in sc, scv 0 handlers Rohan McLure
2022-09-21  6:55 ` [PATCH v6 05/25] powerpc/32: Clarify interrupt restores with REST_GPR macro in entry_32.S Rohan McLure
2022-09-21  6:55 ` [PATCH v6 06/25] powerpc/64e: Clarify register saves and clears with {SAVE,ZEROIZE}_GPRS Rohan McLure
2022-09-21  6:55 ` [PATCH v6 07/25] powerpc/64s: Fix comment on interrupt handler prologue Rohan McLure
2022-09-21  6:55 ` [PATCH v6 08/25] powerpc: Fix fallocate and fadvise64_64 compat parameter combination Rohan McLure
2022-09-21  6:55 ` [PATCH v6 09/25] asm-generic: compat: Support BE for long long args in 32-bit ABIs Rohan McLure
2022-10-31 13:23   ` [PATCH] asm-generic: compat: fix compat_arg_u64 and compat_arg_u64_dual Andreas Schwab
2022-11-01 12:25     ` Michael Ellerman
2022-11-03  8:20     ` Christophe Leroy
2022-11-03  8:48       ` Arnd Bergmann
2022-09-21  6:55 ` [PATCH v6 10/25] powerpc: Use generic fallocate compatibility syscall Rohan McLure
2022-09-21  6:55 ` [PATCH v6 11/25] powerpc/32: Remove powerpc select specialisation Rohan McLure
2022-09-21  6:55 ` [PATCH v6 12/25] powerpc: Remove direct call to personality syscall handler Rohan McLure
2022-09-21  6:55 ` [PATCH v6 13/25] powerpc: Remove direct call to mmap2 syscall handlers Rohan McLure
2022-09-28 12:15   ` Michael Ellerman
2022-09-28 13:00     ` Arnd Bergmann
2022-09-30 13:19       ` Michael Ellerman
2022-09-30 14:09         ` Arnd Bergmann
2022-09-21  6:55 ` [PATCH v6 14/25] powerpc: Provide do_ppc64_personality helper Rohan McLure
2022-09-21  6:55 ` [PATCH v6 15/25] powerpc: Adopt SYSCALL_DEFINE for arch-specific syscall handlers Rohan McLure
2022-09-21  6:55 ` [PATCH v6 16/25] powerpc: Include all arch-specific syscall prototypes Rohan McLure
2022-09-21  6:55 ` [PATCH v6 17/25] powerpc: Enable compile-time check for syscall handlers Rohan McLure
2022-09-21  6:55 ` [PATCH v6 18/25] powerpc: Use common syscall handler type Rohan McLure
2022-09-21  6:55 ` [PATCH v6 19/25] powerpc: Remove high-order word clearing on compat syscall entry Rohan McLure
2022-09-23  7:40   ` Nicholas Piggin
2022-09-28 11:56   ` Michael Ellerman
2022-09-21  6:56 ` [PATCH v6 20/25] powerpc: Change system_call_exception calling convention Rohan McLure
2022-09-23  7:43   ` Nicholas Piggin
2022-09-21  6:56 ` [PATCH v6 21/25] powerpc: Provide syscall wrapper Rohan McLure
2022-09-23  7:50   ` Nicholas Piggin
2022-10-30 15:34   ` Andreas Schwab
2022-10-30 15:50     ` Andreas Schwab
2022-10-30 19:43     ` Arnd Bergmann
2022-10-30 20:05       ` Andreas Schwab
2022-10-31  3:09         ` Michael Ellerman
2022-10-31 14:47   ` [PATCH] powerpc/32: fix syscall wrappers with 64-bit arguments Andreas Schwab
2022-10-31 19:37     ` Arnd Bergmann
2022-11-01 12:25     ` Michael Ellerman
2022-09-21  6:56 ` [PATCH v6 22/25] powerpc/64s: Clear user GPRs in syscall interrupt entry Rohan McLure
2022-09-23  8:02   ` Nicholas Piggin
2022-10-31 23:22     ` Rohan McLure
2022-09-21  6:56 ` [PATCH v6 23/25] powerpc/64: Add INTERRUPT_SANITIZE_REGISTERS Kconfig Rohan McLure
2022-09-21  6:56 ` [PATCH v6 24/25] powerpc/64s: Clear gprs on interrupt routine entry in Book3S Rohan McLure
2022-09-21  6:56 ` Rohan McLure [this message]
2022-10-04 13:24 ` [PATCH v6 00/25] powerpc: Syscall wrapper and register clearing Michael Ellerman

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