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From: Alistair Popple <alistair@popple.id.au>
To: Jordan Niethe <jniethe5@gmail.com>
Cc: npiggin@gmail.com, bala24@linux.ibm.com,
	naveen.n.rao@linux.vnet.ibm.com, linuxppc-dev@lists.ozlabs.org,
	dja@axtens.net
Subject: Re: [PATCH v7 05/28] powerpc: Change calling convention for create_branch() et. al.
Date: Mon, 04 May 2020 12:55:30 +1000	[thread overview]
Message-ID: <3153940.x9l3HivV66@townsend> (raw)
In-Reply-To: <20200501034220.8982-6-jniethe5@gmail.com>

On Friday, 1 May 2020 1:41:57 PM AEST Jordan Niethe wrote:
> create_branch(), create_cond_branch() and translate_branch() return the
> instruction that they create, or return 0 to signal an error. Separate
> these concerns in preparation for an instruction type that is not just
> an unsigned int.  Fill the created instruction to a pointer passed as
> the first parameter to the function and use a non-zero return value to
> signify an error.

We're not adding any new checks for error cases here, but this patch doesn't 
change existing behaviour as far as I can tell and adding checks would be 
difficult (and could introduce other bugs) so would be best done as a separate 
series anyway if required at all.
 
> @@ -403,6 +407,7 @@ static void __init test_trampoline(void)
> 
>  static void __init test_branch_iform(void)
>  {
> +	int err;
>  	unsigned int instr;
>  	unsigned long addr;
> 
> @@ -443,35 +448,35 @@ static void __init test_branch_iform(void)
>  	check(instr_is_branch_to_addr(&instr, addr - 0x2000000));
> 
>  	/* Branch to self, with link */
> -	instr = create_branch(&instr, addr, BRANCH_SET_LINK);
> +	err = create_branch(&instr, &instr, addr, BRANCH_SET_LINK);
>  	check(instr_is_branch_to_addr(&instr, addr));

The pointer alias above initially caught my eye, but it's ok because 
create_branch() doesn't actually dereference the second instance. Arguably the 
argument type could be changed to an unsigned long but then we'd just end up 
with more casts so this is ok to me at least.

Reviewed-by: Alistair Popple <alistair@popple.id.au>




  reply	other threads:[~2020-05-04  2:58 UTC|newest]

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-01  3:41 [PATCH v7 00/28] Initial Prefixed Instruction support Jordan Niethe
2020-05-01  3:41 ` [PATCH v7 01/28] powerpc/xmon: Remove store_inst() for patch_instruction() Jordan Niethe
2020-05-01  3:41 ` [PATCH v7 02/28] powerpc/xmon: Move breakpoint instructions to own array Jordan Niethe
2020-05-04  5:41   ` Alistair Popple
2020-05-04  5:52     ` Jordan Niethe
2020-05-01  3:41 ` [PATCH v7 03/28] powerpc/xmon: Move breakpoints to text section Jordan Niethe
2020-05-01  3:41 ` [PATCH v7 04/28] powerpc/xmon: Use bitwise calculations in_breakpoint_table() Jordan Niethe
2020-05-04  5:41   ` Alistair Popple
2020-05-05  7:08   ` Michael Ellerman
2020-05-05  7:31     ` Jordan Niethe
2020-05-01  3:41 ` [PATCH v7 05/28] powerpc: Change calling convention for create_branch() et. al Jordan Niethe
2020-05-04  2:55   ` Alistair Popple [this message]
2020-05-01  3:41 ` [PATCH v7 06/28] powerpc: Use a macro for creating instructions from u32s Jordan Niethe
2020-05-04  5:54   ` Alistair Popple
2020-05-01  3:41 ` [PATCH v7 07/28] powerpc: Use an accessor for instructions Jordan Niethe
2020-05-01  3:42 ` [PATCH v7 08/28] powerpc: Use a function for getting the instruction op code Jordan Niethe
2020-05-04  8:01   ` Alistair Popple
2020-05-01  3:42 ` [PATCH v7 09/28] powerpc: Use a function for byte swapping instructions Jordan Niethe
2020-05-01  3:42 ` [PATCH v7 10/28] powerpc: Introduce functions for instruction equality Jordan Niethe
2020-05-01  3:42 ` [PATCH v7 11/28] powerpc: Use a datatype for instructions Jordan Niethe
2020-05-02 14:29   ` kbuild test robot
2020-05-02 14:29     ` kbuild test robot
2020-05-01  3:42 ` [PATCH v7 12/28] powerpc: Use a function for reading instructions Jordan Niethe
2020-05-04  8:26   ` Alistair Popple
2020-05-01  3:42 ` [PATCH v7 13/28] powerpc: Add a probe_user_read_inst() function Jordan Niethe
2020-05-04  8:30   ` Alistair Popple
2020-05-01  3:42 ` [PATCH v7 14/28] powerpc: Add a probe_kernel_read_inst() function Jordan Niethe
2020-05-04  9:24   ` Alistair Popple
2020-05-01  3:42 ` [PATCH v7 15/28] powerpc/kprobes: Use patch_instruction() Jordan Niethe
2020-05-05  1:41   ` Alistair Popple
2020-05-01  3:42 ` [PATCH v7 16/28] powerpc: Define and use __get_user_instr{, inatomic}() Jordan Niethe
2020-05-05  1:46   ` Alistair Popple
2020-05-01  3:42 ` [PATCH v7 17/28] powerpc: Introduce a function for reporting instruction length Jordan Niethe
2020-05-05  2:02   ` Alistair Popple
2020-05-01  3:42 ` [PATCH v7 18/28] powerpc/xmon: Use a function for reading instructions Jordan Niethe
2020-05-05  2:07   ` Alistair Popple
2020-05-01  3:42 ` [PATCH v7 19/28] powerpc/xmon: Move insertion of breakpoint for xol'ing Jordan Niethe
2020-05-05  2:19   ` Alistair Popple
2020-05-01  3:42 ` [PATCH v7 20/28] powerpc: Make test_translate_branch() independent of instruction length Jordan Niethe
2020-05-05  2:40   ` Alistair Popple
2020-05-01  3:42 ` [PATCH v7 21/28] powerpc: Enable Prefixed Instructions Jordan Niethe
2020-05-01  3:42 ` [PATCH v7 22/28] powerpc: Define new SRR1 bits for a future ISA version Jordan Niethe
2020-05-05  2:49   ` Alistair Popple
2020-05-01  3:42 ` [PATCH v7 23/28] powerpc: Add prefixed instructions to instruction data type Jordan Niethe
2020-05-05  6:04   ` Alistair Popple
2020-05-01  3:42 ` [PATCH v7 24/28] powerpc: Test prefixed code patching Jordan Niethe
2020-05-05  6:08   ` Alistair Popple
2020-05-01  3:42 ` [PATCH v7 25/28] powerpc: Test prefixed instructions in feature fixups Jordan Niethe
2020-05-05  7:15   ` Alistair Popple
2020-05-05  7:34     ` Jordan Niethe
2020-05-01  3:42 ` [PATCH v7 26/28] powerpc: Support prefixed instructions in alignment handler Jordan Niethe
2020-05-05  7:17   ` Alistair Popple
2020-05-01  3:42 ` [PATCH v7 27/28] powerpc sstep: Add support for prefixed load/stores Jordan Niethe
2020-05-01  3:42 ` [PATCH v7 28/28] powerpc sstep: Add support for prefixed fixed-point arithmetic Jordan Niethe

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