Messages in this thread | | | From | <> | Subject | Re: [PATCH v4] scripts/gdb: add lx_current support for riscv | Date | Tue, 15 Nov 2022 21:23:29 +0000 |
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Hey Deepak,
On 15/11/2022 20:40, Deepak Gupta wrote: > EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe > > csr_sscratch CSR holds current task_struct address when hart is in > user space. Trap handler on entry spills csr_sscratch into "tp" (x2) > register and zeroes out csr_sscratch CSR. Trap handler on exit reloads > "tp" with expected user mode value and place current task_struct address > again in csr_sscratch CSR. > > This patch assumes "tp" is pointing to task_struct. If value in > csr_sscratch is numerically greater than "tp" then it assumes csr_sscratch > is correct address of current task_struct. This logic holds when > - hart is in user space, "tp" will be less than csr_sscratch. > - hart is in kernel space but not in trap handler, "tp" will be more > than csr_sscratch (csr_sscratch being equal to 0). > - hart is executing trap handler > - "tp" is still pointing to user mode but csr_sscratch contains > ptr to task_struct. Thus numerically higher. > - "tp" is pointing to task_struct but csr_sscratch now contains > either 0 or numerically smaller value (transiently holds > user mode tp) > > Patch also adds new cached type "ulong" in scripts/gdb/linux/utils.py >
> Since patch has changed a little bit from v1 and I didn't include > changelog earlier, here it is.
This bit here needs to go below the --- line as it should not end up in the commit logs (as everything below the --- is ignored.
> > --- > v1 --> v2: > - added logic to locate task_struct irrespective of priv > - made locating task_struct agnostic to bitness(32 vs 64). > - added caching of ulong type in scripts/gdb/linux/utils.py > - added more descriptive commit message > > v2 --> v3: > - amended commit message and source line to fit column width > > v3 --> v4: > - amended commit message and remove whitespace in source > - added Reviewed-by for reviewers > --- > > Signed-off-by: Deepak Gupta <debug@rivosinc.com> > Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
And this bit needs to go above the first --- line as it does need to go into the commit logs.
The order is: $subject
body
tags --- changelog & comments
diffs
For example, this is what I see when I apply the patch:
$ b4 shazam 20221115204003.1866421-1-debug@rivosinc.com Grabbing thread from lore.kernel.org/all/20221115204003.1866421-1-debug%40rivosinc.com/t.mbox.gz Checking for newer revisions on https://lore.kernel.org/all/ Analyzing 13 messages in the thread Will use the latest revision: v4 You can pick other revisions using the -vN flag Checking attestation on all messages, may take a moment... --- ✓ [PATCH v4] scripts/gdb: add lx_current support for riscv --- ✓ Signed: DKIM/rivosinc-com.20210112.gappssmtp.com (From: debug@rivosinc.com) --- Total patches: 1 --- Applying: scripts/gdb: add lx_current support for riscv
$ git show commit 5c93617c68980f767e312fc51849d78093f56e72 (HEAD) Author: Deepak Gupta <debug@rivosinc.com> Date: Tue Nov 15 12:40:03 2022 -0800
scripts/gdb: add lx_current support for riscv csr_sscratch CSR holds current task_struct address when hart is in user space. Trap handler on entry spills csr_sscratch into "tp" (x2) register and zeroes out csr_sscratch CSR. Trap handler on exit reloads "tp" with expected user mode value and place current task_struct address again in csr_sscratch CSR. This patch assumes "tp" is pointing to task_struct. If value in csr_sscratch is numerically greater than "tp" then it assumes csr_sscratch is correct address of current task_struct. This logic holds when - hart is in user space, "tp" will be less than csr_sscratch. - hart is in kernel space but not in trap handler, "tp" will be more than csr_sscratch (csr_sscratch being equal to 0). - hart is executing trap handler - "tp" is still pointing to user mode but csr_sscratch contains ptr to task_struct. Thus numerically higher. - "tp" is pointing to task_struct but csr_sscratch now contains either 0 or numerically smaller value (transiently holds user mode tp) Patch also adds new cached type "ulong" in scripts/gdb/linux/utils.py Since patch has changed a little bit from v1 and I didn't include changelog earlier, here it is.
Taken a wee bit of the back and forth, Looks like you're nearly there though!
Conor.
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