kernel.git/arch/powerpc/kernel/entry_32.S, branch linux-6.1.y

powerpc/32: Fix unpaired stwcx. on interrupt exit

2026-01-11T14:18:24Z

[ Upstream commit 10e1c77c3636d815db802ceef588522c2d2d947c ] Commit b96bae3ae2cb ("powerpc/32: Replace ASM exception exit by C exception exit from ppc64") erroneouly copied to powerpc/32 the logic from powerpc/64 based on feature CPU_FTR_STCX_CHECKS_ADDRESS which is always 0 on powerpc/32. Re-instate the logic implemented by commit b64f87c16f3c ("[POWERPC] Avoid unpaired stwcx. on some processors") which is based on CPU_FTR_NEED_PAIRED_STWCX feature. Fixes: b96bae3ae2cb ("powerpc/32: Replace ASM exception exit by C exception exit from ppc64") Signed-off-by: Christophe Leroy Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/6040b5dbcf5cdaa1cd919fcf0790f12974ea6e5a.1757666244.git.christophe.leroy@csgroup.eu Signed-off-by: Sasha Levin

powerpc/47x: Fix 47x syscall return crash

2023-10-19T21:08:56Z

commit f0eee815babed70a749d2496a7678be5b45b4c14 upstream. Eddie reported that newer kernels were crashing during boot on his 476 FSP2 system: kernel tried to execute user page (b7ee2000) - exploit attempt? (uid: 0) BUG: Unable to handle kernel instruction fetch Faulting instruction address: 0xb7ee2000 Oops: Kernel access of bad area, sig: 11 [#1] BE PAGE_SIZE=4K FSP-2 Modules linked in: CPU: 0 PID: 61 Comm: mount Not tainted 6.1.55-d23900f.ppcnf-fsp2 #1 Hardware name: ibm,fsp2 476fpe 0x7ff520c0 FSP-2 NIP: b7ee2000 LR: 8c008000 CTR: 00000000 REGS: bffebd83 TRAP: 0400 Not tainted (6.1.55-d23900f.ppcnf-fs p2) MSR: 00000030 CR: 00001000 XER: 20000000 GPR00: c00110ac bffebe63 bffebe7e bffebe88 8c008000 00001000 00000d12 b7ee2000 GPR08: 00000033 00000000 00000000 c139df10 48224824 1016c314 10160000 00000000 GPR16: 10160000 10160000 00000008 00000000 10160000 00000000 10160000 1017f5b0 GPR24: 1017fa50 1017f4f0 1017fa50 1017f740 1017f630 00000000 00000000 1017f4f0 NIP [b7ee2000] 0xb7ee2000 LR [8c008000] 0x8c008000 Call Trace: Instruction dump: XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX ---[ end trace 0000000000000000 ]--- The problem is in ret_from_syscall where the check for icache_44x_need_flush is done. When the flush is needed the code jumps out-of-line to do the flush, and then intends to jump back to continue the syscall return. However the branch back to label 1b doesn't return to the correct location, instead branching back just prior to the return to userspace, causing bogus register values to be used by the rfi. The breakage was introduced by commit 6f76a01173cc ("powerpc/syscall: implement system call entry/exit logic in C for PPC32") which inadvertently removed the "1" label and reused it elsewhere. Fix it by adding named local labels in the correct locations. Note that the return label needs to be outside the ifdef so that CONFIG_PPC_47x=n compiles. Fixes: 6f76a01173cc ("powerpc/syscall: implement system call entry/exit logic in C for PPC32") Cc: stable@vger.kernel.org # v5.12+ Reported-by: Eddie James Tested-by: Eddie James Link: https://lore.kernel.org/linuxppc-dev/fdaadc46-7476-9237-e104-1d2168526e72@linux.ibm.com/ Signed-off-by: Michael Ellerman Reviewed-by: Christophe Leroy Link: https://msgid.link/20231010114750.847794-1-mpe@ellerman.id.au Signed-off-by: Greg Kroah-Hartman

powerpc/64: use 32-bit immediate for STACK_FRAME_REGS_MARKER

2022-09-28T09:22:12Z

Using a 32-bit constant for this marker allows it to be loaded with two ALU instructions, like 32-bit. This avoids a TOC entry and a TOC load that depends on the r2 value that has just been loaded from the PACA. This changes the value for 32-bit as well, so both have the same value in the low 4 bytes and 64-bit has 0 in the top bytes. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20220926034057.2360083-2-npiggin@gmail.com

powerpc: Change system_call_exception calling convention

2022-09-28T09:22:09Z

Change system_call_exception arguments to pass a pointer to a stack frame container caller state, as well as the original r0, which determines the number of the syscall. This has been observed to yield improved performance to passing them by registers, circumventing the need to allocate a stack frame. Signed-off-by: Rohan McLure Reviewed-by: Nicholas Piggin [mpe: Retain clearing of high bits of args for compat tasks] Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20220921065605.1051927-21-rmclure@linux.ibm.com

powerpc/32: Clarify interrupt restores with REST_GPR macro in entry_32.S

2022-09-26T13:00:15Z

Restoring the register state of the interrupted thread involves issuing a large number of predictable loads to the kernel stack frame. Issue the REST_GPR{,S} macros to clearly signal when this is happening, and bunch together restores at the end of the interrupt handler where the saved value is not consumed earlier in the handler code. Signed-off-by: Rohan McLure Reported-by: Christophe Leroy Reviewed-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20220921065605.1051927-6-rmclure@linux.ibm.com

powerpc: Save caller r3 prior to system_call_exception

2022-09-26T13:00:14Z

This reverts commit 8875f47b7681 ("powerpc/syscall: Save r3 in regs->orig_r3 "). Save caller's original r3 state to the kernel stackframe before entering system_call_exception. This allows for user registers to be cleared by the time system_call_exception is entered, reducing the influence of user registers on speculation within the kernel. Prior to this commit, orig_r3 was saved at the beginning of system_call_exception. Instead, save orig_r3 while the user value is still live in r3. Also replicate this early save in 32-bit. A similar save was removed in commit 6f76a01173cc ("powerpc/syscall: implement system call entry/exit logic in C for PPC32") when 32-bit adopted system_call_exception. Revert its removal of orig_r3 saves. Signed-off-by: Rohan McLure Reviewed-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20220921065605.1051927-3-rmclure@linux.ibm.com

powerpc: Remove CONFIG_PPC_BOOK3E_MMU

2022-09-26T13:00:14Z

CONFIG_PPC_BOOK3E_MMU is redundant with CONFIG_PPC_E500. Remove it. Also rename mmu-book3e.h to mmu-e500.h Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/c5549cd59a131204ff94ab909cad2e2dad4ddf2f.1663606876.git.christophe.leroy@csgroup.eu

powerpc: Change CONFIG_E500 to CONFIG_PPC_E500

2022-09-26T13:00:13Z

It will be used outside arch/powerpc, make it clear its a powerpc configuration item. And we already have CONFIG_PPC_E500MC, so that will make it more consistent. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/e63b22083c11c4300f4a82d3123a46e5fdd54fa6.1663606876.git.christophe.leroy@csgroup.eu

powerpc/rtas: Move rtas entry assembly into its own file

2022-05-19T13:11:27Z

This makes working on the code a bit easier. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20220308135047.478297-2-npiggin@gmail.com

powerpc/config: Add CONFIG_BOOKE_OR_40x

2021-12-09T11:41:19Z

We have many functionnalities common to 40x and BOOKE, it leads to many places with #if defined(CONFIG_BOOKE) || defined(CONFIG_40x). We are going to add a few more with KUAP for booke/40x, so create a new symbol which is defined when either BOOKE or 40x is defined. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/9a3dbd60924cb25c9f944d3d8205ac5a0d15e229.1634627931.git.christophe.leroy@csgroup.eu