From: Rohan McLure <rmclure@linux.ibm.com>
To: linuxppc-dev@lists.ozlabs.org
Cc: Rohan McLure <rmclure@linux.ibm.com>
Subject: [PATCH 20/23] powerpc/64s: Clear/restore caller gprs in syscall interrupt/return
Date: Fri, 16 Sep 2022 15:32:57 +1000 [thread overview]
Message-ID: <20220916053300.786330-21-rmclure@linux.ibm.com> (raw)
In-Reply-To: <20220916053300.786330-1-rmclure@linux.ibm.com>
Clear user state in gprs (assign to zero) to reduce the influence of user
registers on speculation within kernel syscall handlers. Clears occur
at the very beginning of the sc and scv 0 interrupt handlers, with
restores occurring following the execution of the syscall handler.
Signed-off-by: Rohan McLure <rmclure@linux.ibm.com>
---
V1 -> V2: Update summary
V2 -> V3: Remove erroneous summary paragraph on syscall_exit_prepare
V3 -> V4: Use ZEROIZE instead of NULLIFY. Clear r0 also.
V4 -> V5: Move to end of patch series.
---
arch/powerpc/kernel/interrupt_64.S | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/arch/powerpc/kernel/interrupt_64.S b/arch/powerpc/kernel/interrupt_64.S
index 16a1b44088e7..40147558e1a6 100644
--- a/arch/powerpc/kernel/interrupt_64.S
+++ b/arch/powerpc/kernel/interrupt_64.S
@@ -70,7 +70,7 @@ _ASM_NOKPROBE_SYMBOL(system_call_vectored_\name)
ld r2,PACATOC(r13)
mfcr r12
li r11,0
- /* Can we avoid saving r3-r8 in common case? */
+ /* Save syscall parameters in r3-r8 */
SAVE_GPRS(3, 8, r1)
/* Zero r9-r12, this should only be required when restoring all GPRs */
std r11,GPR9(r1)
@@ -110,6 +110,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
* Zero user registers to prevent influencing speculative execution
* state of kernel code.
*/
+ ZEROIZE_GPR(0)
ZEROIZE_GPRS(5, 12)
ZEROIZE_NVGPRS()
bl system_call_exception
@@ -140,6 +141,7 @@ BEGIN_FTR_SECTION
HMT_MEDIUM_LOW
END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
+ REST_NVGPRS(r1)
cmpdi r3,0
bne .Lsyscall_vectored_\name\()_restore_regs
@@ -243,7 +245,7 @@ END_BTB_FLUSH_SECTION
ld r2,PACATOC(r13)
mfcr r12
li r11,0
- /* Can we avoid saving r3-r8 in common case? */
+ /* Save syscall parameters in r3-r8 */
SAVE_GPRS(3, 8, r1)
/* Zero r9-r12, this should only be required when restoring all GPRs */
std r11,GPR9(r1)
@@ -295,6 +297,7 @@ END_BTB_FLUSH_SECTION
* Zero user registers to prevent influencing speculative execution
* state of kernel code.
*/
+ ZEROIZE_GPR(0)
ZEROIZE_GPRS(5, 12)
ZEROIZE_NVGPRS()
bl system_call_exception
@@ -337,6 +340,7 @@ BEGIN_FTR_SECTION
stdcx. r0,0,r1 /* to clear the reservation */
END_FTR_SECTION_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS)
+ REST_NVGPRS(r1)
cmpdi r3,0
bne .Lsyscall_restore_regs
/* Zero volatile regs that may contain sensitive kernel data */
@@ -364,7 +368,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
.Lsyscall_restore_regs:
ld r3,_CTR(r1)
ld r4,_XER(r1)
- REST_NVGPRS(r1)
mtctr r3
mtspr SPRN_XER,r4
REST_GPR(0, r1)
--
2.34.1
next prev parent reply other threads:[~2022-09-16 5:48 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-16 5:32 [PATCH 00/23] powerpc: Syscall wrapper and register clearing Rohan McLure
2022-09-16 5:32 ` [PATCH 01/23] powerpc: Remove asmlinkage from syscall handler definitions Rohan McLure
2022-09-16 5:32 ` [PATCH 02/23] powerpc: Save caller r3 prior to system_call_exception Rohan McLure
2022-09-16 5:32 ` [PATCH 03/23] powerpc: Add ZEROIZE_GPRS macros for register clears Rohan McLure
2022-09-16 5:32 ` [PATCH 04/23] powerpc/64s: Use {ZEROIZE,SAVE,REST}_GPRS macros in sc, scv 0 handlers Rohan McLure
2022-09-16 5:32 ` [PATCH 05/23] powerpc/32: Clarify interrupt restores with REST_GPR macro in entry_32.S Rohan McLure
2022-09-20 0:51 ` Nicholas Piggin
2022-09-16 5:32 ` [PATCH 06/23] powerpc/64e: Clarify register saves and clears with {SAVE,ZEROIZE}_GPRS Rohan McLure
2022-09-20 0:55 ` Nicholas Piggin
2022-09-16 5:32 ` [PATCH 07/23] powerpc/64s: Fix comment on interrupt handler prologue Rohan McLure
2022-09-20 0:55 ` Nicholas Piggin
2022-09-16 5:32 ` [PATCH 08/23] powerpc: Fix fallocate and fadvise64_64 compat parameter combination Rohan McLure
2022-09-16 6:54 ` Arnd Bergmann
2022-09-20 1:01 ` Nicholas Piggin
2022-09-16 5:32 ` [PATCH 09/23] asm-generic: compat: Support BE for long long args in 32-bit ABIs Rohan McLure
2022-09-20 1:06 ` Nicholas Piggin
2022-09-20 7:09 ` Arnd Bergmann
2022-09-16 5:32 ` [PATCH 10/23] powerpc: Use generic fallocate compatibility syscall Rohan McLure
2022-09-16 6:56 ` Arnd Bergmann
2022-09-16 5:32 ` [PATCH 11/23] powerpc/32: Remove powerpc select specialisation Rohan McLure
2022-09-16 5:32 ` [PATCH 12/23] powerpc: Remove direct call to personality syscall handler Rohan McLure
2022-09-16 5:32 ` [PATCH 13/23] powerpc: Remove direct call to mmap2 syscall handlers Rohan McLure
2022-09-16 5:32 ` [PATCH 14/23] powerpc: Provide do_ppc64_personality helper Rohan McLure
2022-09-16 5:32 ` [PATCH 15/23] powerpc: Adopt SYSCALL_DEFINE for arch-specific syscall handlers Rohan McLure
2022-09-16 5:48 ` Rohan McLure
2022-09-20 1:24 ` Nicholas Piggin
2022-09-16 5:32 ` [PATCH 16/23] powerpc: Include all arch-specific syscall prototypes Rohan McLure
2022-09-20 1:27 ` Nicholas Piggin
2022-09-16 5:32 ` [PATCH 17/23] powerpc: Enable compile-time check for syscall handlers Rohan McLure
2022-09-20 1:30 ` Nicholas Piggin
2022-09-16 5:32 ` [PATCH 18/23] powerpc: Use common syscall handler type Rohan McLure
2022-09-20 1:39 ` Nicholas Piggin
2022-09-16 5:32 ` [PATCH 19/23] powerpc: Provide syscall wrapper Rohan McLure
2022-09-20 1:59 ` Nicholas Piggin
2022-09-21 3:44 ` Rohan McLure
2022-09-16 5:32 ` Rohan McLure [this message]
2022-09-20 2:03 ` [PATCH 20/23] powerpc/64s: Clear/restore caller gprs in syscall interrupt/return Nicholas Piggin
2022-09-20 4:54 ` Rohan McLure
2022-09-21 5:33 ` Rohan McLure
2022-09-20 2:07 ` Nicholas Piggin
2022-09-16 5:32 ` [PATCH 21/23] powerpc/64: Add INTERRUPT_SANITIZE_REGISTERS Kconfig Rohan McLure
2022-09-20 2:10 ` Nicholas Piggin
2022-09-16 5:32 ` [PATCH 22/23] powerpc/64s: Clear gprs on interrupt routine entry in Book3S Rohan McLure
2022-09-20 2:27 ` Nicholas Piggin
2022-09-16 5:33 ` [PATCH 23/23] powerpc/64e: Clear gprs on interrupt routine entry on Book3E Rohan McLure
2022-09-16 5:58 ` [PATCH 00/23] powerpc: Syscall wrapper and register clearing Rohan McLure
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