aa3d60f57e
* mvebu-dev: refresh all patches with quilt Cleaned up based on kernel 5.9.12. Signed-off-by: Rosen Penev <rosenp@gmail.com> * mvebu-current: refresh patches with quilt Based on kernel version 5.9.12 Signed-off-by: Rosen Penev <rosenp@gmail.com> * mvebu-legacy: refresh patches with quilt Based on kernel 4.19.161 Signed-off-by: Rosen Penev <rosenp@gmail.com> * mvebu-legacy: remove custom helios4 dts file This is already added upstream. No need to have it here. Continued refreshing the other patches. Signed-off-by: Rosen Penev <rosenp@gmail.com>
159 lines
4.9 KiB
Diff
159 lines
4.9 KiB
Diff
From: "Ard Biesheuvel" <(address hidden)>
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Subject: entry: omit FP emulation for UND exceptions taken in kernel mode
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There are a couple of problems with the exception entry code that deals
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with FP exceptions (which are reported as UND exceptions) when building
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the kernel in Thumb2 mode:
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- the conditional branch to vfp_kmode_exception in vfp_support_entry()
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may be out of range for its target, depending on how the linker decides
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to arrange the sections;
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- when the UND exception is taken in kernel mode, the emulation handling
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logic is entered via the 'call_fpe' label, which means we end up using
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the wrong value/mask pairs to match and detect the NEON opcodes.
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Since UND exceptions in kernel mode are unlikely to occur on a hot path
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(as opposed to the user mode version which is invoked for VFP support
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code and lazy restore), we can use the existing undef hook machinery for
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any kernel mode instruction emulation that is needed, including calling
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the existing vfp_kmode_exception() routine for unexpected cases. So drop
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the call to call_fpe, and instead, install an undef hook that will get
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called for NEON and VFP instructions that trigger an UND exception in
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kernel mode.
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While at it, make sure that the PC correction is accurate for the
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execution mode where the exception was taken, by checking the PSR
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Thumb bit.
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Cc: Dmitry Osipenko <(address hidden)>
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Cc: Kees Cook <(address hidden)>
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Fixes: eff8728fe698 ("vmlinux.lds.h: Add PGO and AutoFDO input sections")
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Signed-off-by: Ard Biesheuvel <(address hidden)>
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Reviewed-by: Linus Walleij <(address hidden)>
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Reviewed-by: Nick Desaulniers <(address hidden)>
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---
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--- a/arch/arm/kernel/entry-armv.S
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+++ b/arch/arm/kernel/entry-armv.S
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@@ -252,31 +252,10 @@ __und_svc:
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#else
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svc_entry
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#endif
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- @
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- @ call emulation code, which returns using r9 if it has emulated
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- @ the instruction, or the more conventional lr if we are to treat
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- @ this as a real undefined instruction
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- @
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- @ r0 - instruction
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- @
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-#ifndef CONFIG_THUMB2_KERNEL
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- ldr r0, [r4, #-4]
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-#else
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- mov r1, #2
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- ldrh r0, [r4, #-2] @ Thumb instruction at LR - 2
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- cmp r0, #0xe800 @ 32-bit instruction if xx >= 0
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- blo __und_svc_fault
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- ldrh r9, [r4] @ bottom 16 bits
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- add r4, r4, #2
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- str r4, [sp, #S_PC]
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- orr r0, r9, r0, lsl #16
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-#endif
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- badr r9, __und_svc_finish
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- mov r2, r4
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- bl call_fpe
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mov r1, #4 @ PC correction to apply
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-__und_svc_fault:
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+ THUMB( tst r5, #PSR_T_BIT ) @ exception taken in Thumb mode?
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+ THUMB( movne r1, #2 ) @ if so, fix up PC correction
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mov r0, sp @ struct pt_regs *regs
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bl __und_fault
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--- a/arch/arm/vfp/vfphw.S
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+++ b/arch/arm/vfp/vfphw.S
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@@ -79,11 +79,6 @@ ENTRY(vfp_support_entry)
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DBGSTR3 "instr %08x pc %08x state %p", r0, r2, r10
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.fpu vfpv2
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- ldr r3, [sp, #S_PSR] @ Neither lazy restore nor FP exceptions
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- and r3, r3, #MODE_MASK @ are supported in kernel mode
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- teq r3, #USR_MODE
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- bne vfp_kmode_exception @ Returns through lr
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-
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VFPFMRX r1, FPEXC @ Is the VFP enabled?
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DBGSTR1 "fpexc %08x", r1
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tst r1, #FPEXC_EN
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--- a/arch/arm/vfp/vfpmodule.c
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+++ b/arch/arm/vfp/vfpmodule.c
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@@ -23,6 +23,7 @@
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#include <asm/cputype.h>
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#include <asm/system_info.h>
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#include <asm/thread_notify.h>
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+#include <asm/traps.h>
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#include <asm/vfp.h>
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#include "vfpinstr.h"
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@@ -642,7 +643,9 @@ static int vfp_starting_cpu(unsigned int
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return 0;
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}
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-void vfp_kmode_exception(void)
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+#ifdef CONFIG_KERNEL_MODE_NEON
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+
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+static int vfp_kmode_exception(struct pt_regs *regs, unsigned int instr)
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{
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/*
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* If we reach this point, a floating point exception has been raised
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@@ -660,9 +663,51 @@ void vfp_kmode_exception(void)
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pr_crit("BUG: unsupported FP instruction in kernel mode\n");
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else
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pr_crit("BUG: FP instruction issued in kernel mode with FP unit disabled\n");
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+ pr_crit("FPEXC == 0x%08x\n", fmrx(FPEXC));
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+ return 1;
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}
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-#ifdef CONFIG_KERNEL_MODE_NEON
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+static struct undef_hook vfp_kmode_exception_hook[] = {{
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+ .instr_mask = 0xfe000000,
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+ .instr_val = 0xf2000000,
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+ .cpsr_mask = MODE_MASK | PSR_T_BIT,
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+ .cpsr_val = SVC_MODE,
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+ .fn = vfp_kmode_exception,
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+}, {
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+ .instr_mask = 0xff100000,
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+ .instr_val = 0xf4000000,
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+ .cpsr_mask = MODE_MASK | PSR_T_BIT,
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+ .cpsr_val = SVC_MODE,
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+ .fn = vfp_kmode_exception,
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+}, {
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+ .instr_mask = 0xef000000,
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+ .instr_val = 0xef000000,
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+ .cpsr_mask = MODE_MASK | PSR_T_BIT,
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+ .cpsr_val = SVC_MODE | PSR_T_BIT,
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+ .fn = vfp_kmode_exception,
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+}, {
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+ .instr_mask = 0xff100000,
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+ .instr_val = 0xf9000000,
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+ .cpsr_mask = MODE_MASK | PSR_T_BIT,
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+ .cpsr_val = SVC_MODE | PSR_T_BIT,
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+ .fn = vfp_kmode_exception,
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+}, {
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+ .instr_mask = 0x0c000e00,
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+ .instr_val = 0x0c000a00,
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+ .cpsr_mask = MODE_MASK,
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+ .cpsr_val = SVC_MODE,
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+ .fn = vfp_kmode_exception,
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+}};
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+
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+static int __init vfp_kmode_exception_hook_init(void)
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+{
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+ int i;
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+
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+ for (i = 0; i < ARRAY_SIZE(vfp_kmode_exception_hook); i++)
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+ register_undef_hook(&vfp_kmode_exception_hook[i]);
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+ return 0;
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+}
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+core_initcall(vfp_kmode_exception_hook_init);
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/*
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* Kernel-side NEON support functions
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