diff options
Diffstat (limited to 'target/linux/brcm2708/patches-4.19/950-0027-Update-vfpmodule.c.patch')
| -rw-r--r-- | target/linux/brcm2708/patches-4.19/950-0027-Update-vfpmodule.c.patch | 137 |
1 files changed, 0 insertions, 137 deletions
diff --git a/target/linux/brcm2708/patches-4.19/950-0027-Update-vfpmodule.c.patch b/target/linux/brcm2708/patches-4.19/950-0027-Update-vfpmodule.c.patch deleted file mode 100644 index 7fd6024715..0000000000 --- a/target/linux/brcm2708/patches-4.19/950-0027-Update-vfpmodule.c.patch +++ /dev/null @@ -1,137 +0,0 @@ -From 0eb679e4b41dab1e421415917feae44d00e1687f Mon Sep 17 00:00:00 2001 -From: Claggy3 <stephen.maclagan@hotmail.com> -Date: Sat, 11 Feb 2017 14:00:30 +0000 -Subject: [PATCH] Update vfpmodule.c - -Christopher Alexander Tobias Schulze - May 2, 2015, 11:57 a.m. -This patch fixes a problem with VFP state save and restore related -to exception handling (panic with message "BUG: unsupported FP -instruction in kernel mode") present on VFP11 floating point units -(as used with ARM1176JZF-S CPUs, e.g. on first generation Raspberry -Pi boards). This patch was developed and discussed on - - https://github.com/raspberrypi/linux/issues/859 - -A precondition to see the crashes is that floating point exception -traps are enabled. In this case, the VFP11 might determine that a FPU -operation needs to trap at a point in time when it is not possible to -signal this to the ARM11 core any more. The VFP11 will then set the -FPEXC.EX bit and store the trapped opcode in FPINST. (In some cases, -a second opcode might have been accepted by the VFP11 before the -exception was detected and could be reported to the ARM11 - in this -case, the VFP11 also sets FPEXC.FP2V and stores the second opcode in -FPINST2.) - -If FPEXC.EX is set, the VFP11 will "bounce" the next FPU opcode issued -by the ARM11 CPU, which will be seen by the ARM11 as an undefined opcode -trap. The VFP support code examines the FPEXC.EX and FPEXC.FP2V bits -to decide what actions to take, i.e., whether to emulate the opcodes -found in FPINST and FPINST2, and whether to retry the bounced instruction. - -If a user space application has left the VFP11 in this "pending trap" -state, the next FPU opcode issued to the VFP11 might actually be the -VSTMIA operation vfp_save_state() uses to store the FPU registers -to memory (in our test cases, when building the signal stack frame). -In this case, the kernel crashes as described above. - -This patch fixes the problem by making sure that vfp_save_state() is -always entered with FPEXC.EX cleared. (The current value of FPEXC has -already been saved, so this does not corrupt the context. Clearing -FPEXC.EX has no effects on FPINST or FPINST2. Also note that many -callers already modify FPEXC by setting FPEXC.EN before invoking -vfp_save_state().) - -This patch also addresses a second problem related to FPEXC.EX: After -returning from signal handling, the kernel reloads the VFP context -from the user mode stack. However, the current code explicitly clears -both FPEXC.EX and FPEXC.FP2V during reload. As VFP11 requires these -bits to be preserved, this patch disables clearing them for VFP -implementations belonging to architecture 1. There should be no -negative side effects: the user can set both bits by executing FPU -opcodes anyway, and while user code may now place arbitrary values -into FPINST and FPINST2 (e.g., non-VFP ARM opcodes) the VFP support -code knows which instructions can be emulated, and rejects other -opcodes with "unhandled bounce" messages, so there should be no -security impact from allowing reloading FPEXC.EX and FPEXC.FP2V. - -Signed-off-by: Christopher Alexander Tobias Schulze <cat.schulze@alice-dsl.net> ---- - arch/arm/vfp/vfpmodule.c | 25 +++++++++++++++++++------ - 1 file changed, 19 insertions(+), 6 deletions(-) - ---- a/arch/arm/vfp/vfpmodule.c -+++ b/arch/arm/vfp/vfpmodule.c -@@ -179,8 +179,11 @@ static int vfp_notifier(struct notifier_ - * case the thread migrates to a different CPU. The - * restoring is done lazily. - */ -- if ((fpexc & FPEXC_EN) && vfp_current_hw_state[cpu]) -+ if ((fpexc & FPEXC_EN) && vfp_current_hw_state[cpu]) { -+ /* vfp_save_state oopses on VFP11 if EX bit set */ -+ fmxr(FPEXC, fpexc & ~FPEXC_EX); - vfp_save_state(vfp_current_hw_state[cpu], fpexc); -+ } - #endif - - /* -@@ -462,13 +465,16 @@ static int vfp_pm_suspend(void) - /* if vfp is on, then save state for resumption */ - if (fpexc & FPEXC_EN) { - pr_debug("%s: saving vfp state\n", __func__); -+ /* vfp_save_state oopses on VFP11 if EX bit set */ -+ fmxr(FPEXC, fpexc & ~FPEXC_EX); - vfp_save_state(&ti->vfpstate, fpexc); - - /* disable, just in case */ - fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN); - } else if (vfp_current_hw_state[ti->cpu]) { - #ifndef CONFIG_SMP -- fmxr(FPEXC, fpexc | FPEXC_EN); -+ /* vfp_save_state oopses on VFP11 if EX bit set */ -+ fmxr(FPEXC, (fpexc & ~FPEXC_EX) | FPEXC_EN); - vfp_save_state(vfp_current_hw_state[ti->cpu], fpexc); - fmxr(FPEXC, fpexc); - #endif -@@ -531,7 +537,8 @@ void vfp_sync_hwstate(struct thread_info - /* - * Save the last VFP state on this CPU. - */ -- fmxr(FPEXC, fpexc | FPEXC_EN); -+ /* vfp_save_state oopses on VFP11 if EX bit set */ -+ fmxr(FPEXC, (fpexc & ~FPEXC_EX) | FPEXC_EN); - vfp_save_state(&thread->vfpstate, fpexc | FPEXC_EN); - fmxr(FPEXC, fpexc); - } -@@ -597,6 +604,7 @@ int vfp_restore_user_hwstate(struct user - struct thread_info *thread = current_thread_info(); - struct vfp_hard_struct *hwstate = &thread->vfpstate.hard; - unsigned long fpexc; -+ u32 fpsid = fmrx(FPSID); - - /* Disable VFP to avoid corrupting the new thread state. */ - vfp_flush_hwstate(thread); -@@ -619,8 +627,12 @@ int vfp_restore_user_hwstate(struct user - /* Ensure the VFP is enabled. */ - fpexc |= FPEXC_EN; - -- /* Ensure FPINST2 is invalid and the exception flag is cleared. */ -- fpexc &= ~(FPEXC_EX | FPEXC_FP2V); -+ /* Mask FPXEC_EX and FPEXC_FP2V if not required by VFP arch */ -+ if ((fpsid & FPSID_ARCH_MASK) != (1 << FPSID_ARCH_BIT)) { -+ /* Ensure FPINST2 is invalid and the exception flag is cleared. */ -+ fpexc &= ~(FPEXC_EX | FPEXC_FP2V); -+ } -+ - hwstate->fpexc = fpexc; - - hwstate->fpinst = ufp_exc->fpinst; -@@ -690,7 +702,8 @@ void kernel_neon_begin(void) - cpu = get_cpu(); - - fpexc = fmrx(FPEXC) | FPEXC_EN; -- fmxr(FPEXC, fpexc); -+ /* vfp_save_state oopses on VFP11 if EX bit set */ -+ fmxr(FPEXC, fpexc & ~FPEXC_EX); - - /* - * Save the userland NEON/VFP state. Under UP, |